Interactive effects of moisture, temperature and decomposition stage on respirational carbon loss from coarse woody debris (CWD) of important European tree species

¹ Steffen Herrmann, Swiss Federal Research Institute WSL

² Jürgen Bauhus, University of Freiburg

Coarse woody debris (CWD) is critical for forest ecosystem carbon (C) storage. Since its turnover is mostly driven by mineralization, changes in temperature and precipitation may influence the pools and functions of CWD. Therefore, we analysed the effect of wood temperature and moisture on the C respiration from CWD for Fagus sylvatica, Picea abies and Pinus sylvestris in different stages of decay under controlled conditions. Additionally, we measured CWD respiration over one year in the field for F. sylvatica and P. abies logs and analysed the effect of substrate specific, micro-climatic and environmental variables. The CO2 flux from beech woody debris was about two times higher than that of spruce and pine. Under controlled conditions, wood moisture exerted a stronger influence on respiration than wood temperature. In contrast, temperature was most important in the field observations. Field respiration rates of spruce and beech were similarly temperature sensitive (Q10 3.49 and 3.23). Wood density interacted with temperature to influence the CO2 flux from beech under controlled conditions, and it correlated significantly with CO2 flux from beech and spruce logs in the field. Between 60 and 70% of the whole variation in respiration under controlled conditions and in the field could be explained by stepwise linear regressions. Further, we predicted average monthly temperatures of CWD in the field very accurately from air temperature (r2=0.96), which may be highly relevant for modelling CWD-C dynamics under climate change scenarios.

Old-growth characteristics of disjunct Thuja occidentalis stands at their northwestern distribution limit, central Canada.

¹ Karine Grotte, Centre for Forest Interdisciplinary Research (C-FIR)

² Derrick Ko Heinrichs, University of Winnipeg

³ Jacques Tardif, Centre for Forest Interdisciplinary Research (C-FIR), University of Winnipeg

Old-growth northern white-cedar (Thuja occidentalis L.) stands were examined in the Mid-Boreal Lowlands of west-central Manitoba. These stands represent the northwestern limit of distribution of the species are disjunct from its continuous range limit in North America. The objectives involved characterizing the vegetation – environmental relationships, forest structure and old-growth attributes of these stands. The environmental control on these communities was explored with both cluster analysis and canonical correspondence analysis. Three T. occidentalis stand types over 250 years of age were identified, each representing a specific moisture regime and successional pathway. Thuja occidentalis co-occurred with jack pine (Pinus banksiana Lamb.) in the xeric sites, white spruce (Picea glauca (Moench) Voss) and balsam fir (Abies balsamea (L.) Mill.) in the mesic sites, and tamarack (Larix laricina (Du Roi) K. Koch) in the hydric sites. Snag density, basal area, frequency of occurrence by species and decay class was determined. Coarse woody debris (CWD) was also quantified to determine volume and decay. The more productive mesic stands had larger trees, a higher density and basal area of snags and a significantly greater volume of CWD than the other two stand types. The variation of volume of deadwood found in these stands reflects the differences in site productivity and species assemblages. Being that the mesic sites were not the oldest studied the results indicate that deadwood accumulation in these forests is more reliant on stand dynamics than age.

Diversity of Saproxylic Coleoptera in Great Smoky Mountains National Park

¹ Michael Ferro, Louisiana State University

² Christopher Carlton, Louisiana State University

A study of saproxylic beetles was conducted during 2006 and 2007 in Great Smoky Mountains National Park, Tennessee, USA. Six sites, three each in primary and secondary forests were sampled. Emergence chambers were used to collect beetles from dead wood of two sizes (fine = 2.5-7.0 cm diameter, coarse = 8.0-20.0 cm diameter) and three decay classes from each site. Primary forest sites had a significantly higher volume of CWD than secondary sites. During two years a total of 5692 adult Coleoptera specimens representing 50 families, 226 genera, and 275+ species were collected with emergence chambers. Samples (three each) of leaf litter and CWD decay class 5 were collected at each site during fall and spring, resulting in the collection of 4263 adult Coleoptera specimens in 143+ genera. During summer 2007 flight intercept traps (FIT) were used to collect beetles at one primary and one secondary forest site resulting in the collection of 2472 adult Coleoptera specimens. Preliminary results include: 1) the collection of numerous saproxylic beetle species that are presumed to be rare, many species not previously reported from the park, and several undescribed species; 2) conclusive evidence that leaf litter and CWD decay class 5 have distinctly different beetle communities; 3) and data showing that short term FITs are a poor collection method for saproxylic beetles, but does yield beetle species not collected from litter or emergent from wood.

Does dead wood leave a footprint in the soil?

¹ Tiemo Kahl, Institute of Silviculture, University of Freiburg, Germany

The transport of carbon from coarse woody debris logs (CWD) to the soil as well as to the soil organic carbon (SOC) pools under and beside beech (Fagus sylvatica) CWD in the NP Hainich, Germany were investigated. Drainage water under CWD was analysed for dissolved organic carbon (DOC) and in a paired sampling design soil samples were taken under and beside (control) CWD. Results showed that high DOC fluxes (76 gCm-2y-1) from CWD to the soil exist (control: 4.2 gCm-2y-1). Despite this fact, the SOC pools under CWD did not increase within a timeframe of 30 years. The DOC from CWD showed significantly higher d13C values than the control. These values reflect the isotopic differences between wood vs. litter and roots. With these isotopic differences it was possible to follow the fate of the carbon from CWD to the soil. Down to 10 cm mineral soil depth a significantly higher d13C value was found in the SOC under CWD. The carbon from CWD exchanges within 20 years about 20% of the SOC pool under the CWD without any significant changes to the SOC pool. It is probable that the exchanged carbon is completely mineralised in the soil.

Deadwood in European forests

¹ Tor-Bjorn Larsson, Swedish University of Agricultural Sciences

² Anna Barbati, University of Tuscia, Dept of Forest Environment and Resources

³ Gherardo Chirici, University of Molise

⁴ Hans Gardfjell, Dept of Forest Resource Management

⁵ Roman Michalak, Swedish University of Agricultural Sciences

⁶ John O' Halloran, Dept of Forest Resource Management

⁷ Oisín Sweeney, School of Biological, Earth and Environmental Sciences, Enterprise Centre, Distillery Fields, University College Cork

Reporting of volumes of deadwood in the European states has been part of the European Ministerial Forest Process since 1998. The first presentation of deadwood in the report MCPFE/UNECE/FAO ‘State of Europe’s Forests 2007’ revealed a great heterogeneity among countries. Furthermore the issue of ‘how much is enough’ was raised. At the upcoming Ministerial Conference in 2011 improved deadwood data are expected. Most importantly reporting according following the new scheme of European Forest Types should allow a better analysis. Monitoring of deadwood is also increasingly improved and harmonized in e.g. the National Forest Inventories (NFI) even if the COST action E43 demonstrated that relevant differences in definitions and assessment methods exist across the countries. At the Symposium most recent European figures on deadwood will be presented. Additionally three national ‘case studies’ on deadwood monitoring and assessment will be presented. Sweden, having the largest forest area of the EU member states, has been monitoring deadwood for decades through the National Forest Inventory. More details will be presented comparing e.g. protected forests with production forests. Some ideas of assessment of deadwood as an indicator on ‘favorable conservation status’ according to the EU Habitat Directive will also be presented. Ireland, with an ambitious forest policy, relies heavily on forest plantation of exotic tree species. Management measures to increase the amount of deadwood in Irish forests will be discussed. In Italy in a network of old-growth forests deadwood was recently assessed and compared with figures reported by the NFI in order to define suggestions for forest management policies.

Reproductive trade-offs by red-breasted nuthatch (Sitta canadensis) imposed by a community-wide resource pulse of mountain pine bark beetles (Dendroctonus ponderosae) in interior British Columbia

¹ Andrea Norris, Centre for Applied Conservation Research, Forest Sciences Centre, University of British Columbia

² Kathy Martin, University of British Columbia, Canada

Large-scale forest insect outbreaks can result in immediate increases in food availability, and lagged increases in the availability of dead wood for insectivorous bird communities. Dead and dying trees provide a critical nesting resource for cavity-nesting communities that comprise many species of nest cavity producers, consumers, and predators. Thus forest insect outbreaks can ameliorate food and nest-site constraints, but community-wide increases in population densities may result in increases in competition and predation. We examined how a community-wide food pulse of mountain pine bark beetles (Dendroctonus ponderosae) influenced fecundity, competition for cavities, and nest predation for a bark insectivorous cavity-nester, red-breasted nuthatch (Sitta canadensis), at 30 sites in interior British Columbia, during 1995-2009. We show that nuthatch populations experienced increased reproductive output at sites with high bark beetle abundance. However, higher densities of competitors and predators at these sites led to increased competition for cavities, and increased nest predation rates. The result that nuthatches traded off lower competition and nest predation risk for higher food availability during the beetle outbreak suggests that retention of dead and dying cavity-bearing trees may be especially important during insect outbreaks for long-term maintenance of cavity-nesting communities.

Carbon pools and nutrient dynamics associated with deadwood under two contrasting boreal species

¹ Suzanne Brais, UQAT - Chaire AFD & CEF

² Pascal Drouin, UQAT

Decaying wood contributes to the biochemical and structural heterogeneity of forest soils. The magnitude of this contribution could however depend on tree species and wood decay stage. This study took place in an 85-year old, post-fire aspen – jack pine forest in northwestern Quebec, Canada. Inventories and sampling of trees, logs and forest floor originating from buried wood (lignic FF) and from fine litter (alignic FF) were conducted in fifteen 400 m2 sample plots (9 jack pine, 6 aspen ) equally distributed and nested within three sampling sectors. Relative nutrient availability in the mineral soil was assessed under fresh and well-decomposed logs and under lignic and alignic FF using PRSTM probes. Data were analyzed by GLM using a compound symmetry approach to model correlations between nested observations. Despite higher well-decomposed log volumes in jack pine stands, no significant differences between covers were found for the proportion of C and nutrients contained in biomass + necromass pools. Lignic FF was characterized by a higher C to N ratio and exchangeable acidity and a lower cationic exchange capacity than alignic FF and its nutrient concentrations were halfway between those of alignic FF and logs. Nutrient availability in the mineral soil was not linked to nutrient concentration of overlying necromass and higher Ca and Mg availability was observed under logs than under alignic FF. Differences in wood characteristics may explain some of the differences in soil properties observed between aspen and jack pine stands and usually attributed to fine litter quality.

Debris Down Under: coarse woody debris loads in the cool temperate forests of Tasmania, Australia

¹ Martin T. Moroni, Forestry Tasmania

² Ian Riley, Forestry Tasmania

³ David Mannes, Forestry Tasmania

⁴ Simon Grove, Forestry Tasmania

Tasmania is Australia’s southernmost state, and much of the island experiences a cool temperate climate. Its native forests occupy a range of altitudes and occur under a range of rainfall regimes, and vary from dry open eucalypt woodland to dense rainforest. Non-stand-replacing wildfires are the predominant natural disturbance agent in most forest types, and result in mixed-age stands in which coarse woody debris (CWD) loads are highly variable in space and time. This variability has defied past attempts to evaluate CWD loads across the state. However, through a combination of experimental studies and inventory data, we have for the first time attempted to determine CWD loads across the spectrum of forest types present in Tasmanian state forests, including those managed for timber. While CWD is scarce in some forest types, typical loads in lowland wet eucalypt forest are exceptionally high by international standards, rivalling those of the Pacific Northwest. Our studies demonstrate the significant role that coarse woody debris is likely to play in both forest ecology and carbon cycling in Tasmania.

Past and present state of dead wood and senescent trees in the Sonian Forest (Belgium), a woodland of great importance to kings and emperors, and old-growth biodiversity.

¹ Kris Vandekerkhove, Institute for Nature and Forest Research

² Luc De Keersmaeker, Institute for Nature and Forest Research

³ Ruben Walleyn, Institute for Nature and Forest Research

⁴ Frank Köhler, Koleopterologisches Forschungsbüro

⁵ Luc Crevecoeur, Nature research coordination - Province of Limburg

Forests in Belgium have been scarce and intensively managed for centuries, with senescent and dead trees virtually absent. Sonian Forest, a 5000 ha forest area at the verge of Brussels, was for more than 800 years privileged to dukes, kings and Habsburg Emperors, and was of high economic and strategic, but also recreational value to them. Based on historic archive documents and extensive inventories, past and current state of overmature trees and dead wood are described. Special attention is given to an area of strict reserve that has been left unmanaged for over 25 years. In addition, specific inventories of old-growth related biodiversity (saproxylic beetles and fungi) were performed. The results show that aesthetic aspects of senescent trees played an important role in past management. At present the number and density of old trees, especially beech trees, are extraordinary high. Amounts of dead wood have been extremely low, and still are quite low with less than 10 m³/ha on average. However, in the unmanaged area, amounts have quickly increased to over 130 m³/ha, especially due to heavy windstorm events. Finally, some preliminary results from fungi and beetle inventories confirm the high potential for biodiversity that could be derived from the specific history and current state of the site : the forest proves to be one of the most important hotspot-sites for old-growth related biodiversity in the Low Countries.

Disturbance history influences downed woody debris respiration

¹ Ulrike Hagemann, Institute of Soil Science and Site Ecology

² Martin T. Moroni, Forestry Tasmania

³ Johanna Gleißner, Geo and Hydro Sciences

⁴ Franz Makeschin, Dresden University of Technology

In boreal forests, disturbances such as stand-replacing fires and clearcut harvesting create large amounts of downed woody debris (DWD), which release considerable amounts of CO2 to the atmosphere during decomposition. Harvesting and fire differ with respect to DWD characteristics, decomposition environment, and abundance. Differences in DWD respiration rates between stands of different disturbance history can therefore be expected. From July to September 2008, we periodically measured temperatures, moisture content, weight, and respiration of 45 standardized black spruce logs placed in three old-growth (>140 years), three clearcut harvested (3 years prior), and three burned (23 years prior) black spruce stands in Labrador, Canada. Concurrently, soil temperatures, moisture potential, and respiration were measured next to each log. Moisture content was the dominant environmental control of DWD respiration, followed by temperature. Within-log differences in moisture and temperature resulted from drying of the log surface and water transfer from the moss layer to the log. Wood temperatures were higher in disturbed stands compared to old-growth stands. Piece-level DWD respiration rates were highest in harvested stands, while low DWD moisture levels limited respiration in burned stands. Compared to soil respiration, stand-level DWD respiration reached similar (post-fire) or equal (post-harvest) rates. Disturbance-induced changes in temperature and moisture regimes are reflected by DWD respiration rates, and decomposition rates of forest C models should hence be differentiated by disturbance-specific decomposition environment.

First large-scale assessment of the amount of CWD in strict French forest reserves.

¹ Nicolas Debaive, Réserves Naturelles de France / Office National des Forêts

² Olivier Gilg, Réserves Naturelles de France

³ Loïc Duchamp, Sycoparc

⁴ Nicolas Drapier, Office National des Forêts

⁵ Yoan Paillet, Cemagref

⁶ Frédéric Gosselin, Cemagref

⁷ Max Bruciamacchie, Agroparistech - ENGREF

Deadwood, whether expressed in volume, diversity or continuity, is nowadays widely acknowledged as being an important component of forest ecosystems and has therefore been addressed in most recent studies dealing with forest conservation and management. However, and despite the growing use of the concept of naturalness in the management plans of French forest reserves, deadwood dynamics remain greatly unknown in European temperate forests. In this context and to answer a growing demand arising from reserve managers, a long-term monitoring scheme has been launched in 2005. Preliminary results from 42 French forest reserves will be presented in this talk. A comprehensive data set of living and dead tree measurements have so far been collected on more than 4000 permanent plots. Sampling is systematic but the density of plots is adjusted to the reserve size, habitat diversity and management practices. Overall, French forest reserves host an average of 35.1 m3/ha of deadwood. More than 2/3 of the reserves had deadwood volumes between 20 and 40 m3/ha, and were considered “deadwood rich”. For more than 1/3 of these reserves, the estimated volume was even greater than 40 m3/ha, indicative of forests growing under nearly natural conditions. Although most of the reserves showed a significant amount of deadwood, the gap with old-growth forests is still of great magnitude. The following surveys should allow us to better understand these differences.

Spatial occurrence patterns and habitat requirements of a threatened beetle, Upis ceramboides, in a managed boreal forest landscape

¹ Diana Rubene, Department of Ecology

² Lars-Owe Wikars, Swedish University of Agricultural Sciences

³ Thomas Ranius, Dept. of Ecology, Swedish University of Agricultural Sciences

Since forest fires are today scarce in Fennoscandia, sun-exposed dead wood on clear-cuts can be important for saproxylic species, adapted to burned forest habitats. We have investigated occurrence patterns and habitat requirements of a threatened beetle, Upis ceramboides, in repeated surveys 2003-2004 and 2010, in a managed boreal forest landscape in Sweden. The species has gone regionally extinct from southern Sweden. The studied population is currently the southernmost and rather isolated from the larger occurrence area in the north. U. ceramboides requires sun-exposed, moderately-decayed birch logs for larval development and appears to have a higher frequency of occurrence in dead wood items situated in parts of clear-cuts with highest density of suitable logs. Occurrence of the species per clear-cut is strongly dependent on amount of dead birch wood. Even time since clear-cutting is important, as U. ceramboides was found mostly on six to eleven year old clear-cuts. Between 2004 and 2010, we observed a clear decline in occurrence of U. ceramboides – from 30% to 4% of all clear-cuts. A possible factor causing the decline is habitat degradation, if the species respond with a time lag to decreasing amounts and quality of dead wood, or decreasing proportion of deciduous trees in the managed forest stands. Even changes in competitive interactions with other species, as a consequence of climate change, are plausible and could be studied further in the future.

Contribution of Downed Woody Debris to Biomass and Nutrient Pools in Boreal Mixedwoods of Northeastern Ontario

¹ Jessica Iraci, University of Toronto

² Jay R. Malcolm, University of Toronto

³ Dave Morris, Ontario Ministry of Natural Resources

Harvest-related decreases in the amount of downed woody debris (DWD) in forests may have important implications for stand development and nutrient cycling; however, patterns of nutrient release from decaying DWD are poorly understood. We investigated the importance of DWD relative to other major biomass and nutrient pools in six, second-growth (36-65 year old) boreal mixedwood forest stands near Kapuskasing, Ontario. Nutrient concentrations during decay of balsam fir (Abies balsamea) and trembling aspen (Populus tremuloides) also were determined. Wood density of trembling aspen and balsam fir DWD decreased approximately exponentially with decay; however, on a per g basis, concentrations of N, P, Ca, and Mg increased with decay class, especially for aspen, whereas concentrations of K decreased. Stands had an average aboveground biomass (live biomass plus forest floor) of 180 T· ha-1, with trees and DWD accounting for 84 and 4% of this quantity, respectively. Nutrient pools of aboveground biomass were: 617 kg·ha-1 for N; 55 kg ha-1 for P; 1217 kg·ha-1 for Ca; 95 kg·ha-1 for Mg ; and 321 kg·ha-1 for K. Tree biomass dominated the aboveground nutrient pools, with respective DWD contributions being only 3, 2, 3, 4, and 2%. Due to it its large mass, soil (including the O and mineral layers) tended to dominate total ecosystem carbon and macronutrient pools, representing 43, 87, 92, and 51% of the respective nutrient pools and 91% of the carbon pool. Within the detritus pool (DWD, litter, and organic soil), soil organic matter dominated by weight (63%) and was even more dominant among macronutrient pools (69-80%). Conversely, although contributing 12% by mass, DWD contributed only 2-8% of macronutrients to this pool. These results suggest that in these closed-canopy, second growth forests, DWD comprises a relatively minor pool of nutrients compared to its contribution to carbon pools. However, the potential value of a diverse array of log species and decay classes is highlighted because of differential nutrient contributions as a function of species and time; for example, the relative high concentration of K in early decay class wood, especially for balsam fir, versus the increasing concentrations of N and P through the decay class sequence.

A decade of change in the saproxylic beetle fauna of eucalypt logs in the Warra long-term log-decay experiment, Tasmania

¹ Simon Grove, Forestry Tasmania

² Lynette Forster, University of Tasmania

The first decade of eclector-trap sequential and cyclical sampling of twelve freshly-felled Eucalyptus obliqua logs at Warra, Tasmania has allowed us to document a rich but poorly described saproxylic beetle fauna, and to compare the fauna of larger-diameter (>60 cm) logs originating from mature eucalypts with that of smaller-diameter (<40 cm) logs originating from regrowth eucalypts. Neither obligately nor facultatively saproxylic beetles dominated, but predators predominated over other larval feeding guilds, and winged species predominated over functionally flightless species. The distribution of individuals among species was typically skewed. The two log-classes supported different assemblages. The mature log-class hosted consistently more species, more unique species, and proportionally more obligately saproxylic species than the regrowth log-class; this effect could not readily be attributed to having sampled a larger amount of log. Assemblages changed seasonally and year-to-year. Assemblages in the two log-classes, while following similar trajectories of change, nevertheless remained distinct at every point in time. These differences remained apparent when considering a range of sub-sets of the assemblages based on the rarity of the species involved, their flightedness, saproxylicity and larval feeding guild, indicating that all sub-sets are responsive to the log-size differences and to succession. The experiment is still in its infancy, and is intended to run for as long as it takes the logs to decay – some two hundred years.

The origin of dead wood does matter for saproxylic beetles

¹ Jonathan Boucher, UQAC & RNCan

² Jacques Ibarzabal, UQAC & CEF

³ Ermias Azeria, RNCan

⁴ Christian Hébert, RNCan

Saproxylic species have evolved with dead wood dynamics characterizing their habitat range. Since wildfires are the main source of snags in northern boreal forest, fire killed trees are thus a key component for many saproxylic species. So far, we do not know the relative contribution of fires for maintaining biodiversity, compared to other disturbances. In this context, our study aimed at discriminating burn-associated species from those associated with unburned recently killed snags, in the northern boreal forest of Quebec, Canada. In June 2008, we collected 80 logs from Black spruce and Jack pine snags that were either burned by wildfires in 2007 or girdled in 2006. Each treatment (tree species × perturbation) was replicated 5 times. In each site 2 trees were cut down, from which we harvested 2 logs, one at 0.7 m from the ground and the other at 1.3 m. Logs were reared in a field insectarium over 17 months. We identified 22 648 insects distributed among 35 species and 7 families (Cerambycidae, Cleridae, Corylophidae, Curculionidae, Lathridiidae and Salpingidae). Abundance patterns were mainly explained by disturbance type with girdled trees yielding more individuals than burned trees. Species richness was higher in black spruce than in jack pine. More species were found to be associated with girdling and with black spruce, without considering disturbances. We found a clear distinction in assemblages between disturbances. The effect of tree species on assemblages was greater within girdled logs.

Influence of tree characteristics and forest management on tree microhabitats

¹ Yoan Paillet, Cemagref

² Aurélie Vuidot, Cemagref

³ Frédéric Archaux, Cemagref

⁴ Frédéric Gosselin, Cemagref

Higher densities of tree microhabitats in unmanaged forests may explain biodiversity differences with managed forests. To better understand the determinants of this potential biodiversity indicator, we studied the influence of tree characteristics on a set of tree microhabitats (cavities, cracks, bark features) on 75 plots in managed and unmanaged French forests. We hypothesized that the number of different microhabitat types per tree and the occurrence of a given microhabitat type on a tree would be higher in unmanaged than in managed forests, and that this difference could be linked to individual tree characteristics: diameter, vitality (living versus deadwood) and species. We show that unmanaged forests contained more trees likely to host microhabitats (large trees, snags) at the stand level. However, at the tree level, forest management did not influence microhabitats; only tree characteristics did: large trees and snags contained more microhabitats. The number and occurrence of microhabitats also varied with tree species: oaks and beech generally hosted more microhabitats, but occurrence of certain types of microhabitats was higher on fir and spruce. We conclude that, even though microhabitats are not equally distributed between managed and unmanaged forests, two trees with similar characteristics in similar site conditions have the same number and probability of occurrence of microhabitats, whatever the management type. In order to preserve biodiversity, foresters could reproduce unmanaged forest features in managed forests through the conservation of specific tree types (veteran trees, snags). Tree microhabitats could also be more often targeted in sustainable forest management monitoring.

Modelling woodborer damage in recently burned logs, as a function of temperature

¹ Sébastien Bélanger, Consortium iFor

² Éric Bauce, Laval University, Consortium iFor

³ Christian Hébert, RNCan

⁴ Bernard Long, RNCan - Service canadien des forêts

⁵ Richard Berthiaume, Consortium iFor

Because of a decrease in timber availability, salvage logging is used to maintain wood supply for the forest industry. In boreal forests, recent burns are the main areas targeted by this strategy. However, the quality of this wood for the sawmill industry is rapidly deteriorated by woodborers. These insects take advantage of the sudden availability of an abundant food resource and their larvae cause damage by burrowing galleries into the wood. These galleries decrease the economic value of wood products. This project aimed to reduce economic losses caused by woodborers, by modeling the seasonal progression of their damage as a function of temperature. We exposed logs of recently burned black spruce (Picea mariana) and jack pine (Pinus banksiana) to females of the woodborer Monochamus scutellatus scutellatus for 48 hours. Then, logs were placed in different temperatures (12, 16, 20, 24 and 28°C) and scanned regularly with an x ray tomograph to monitor larval gallery progression. This was done by reconfigurating three-dimensional images with the MATLAB© software. Our analyses showed a rapid rate of progression of larvae into the logs submitted to high temperatures (24 and 28°C).

Tree-microhabitats in the montane Beech-Fir forests of the Pyrenees (France:) Revealing girth thresholds correlated with microhabitat occurrences

¹ Laurent Larrieu, INRA

² Alain Cabanettes, UMR 1201

The focus on tree microhabitats as a proxy for taxonomic biodiversity is recommended because biodiversity assessments in forests using bio-indicator tools are very expensive and require taxonomic specialists. However, few quantitative data are available for forest managers to apply tree microhabitats as a criteria. We selected 10 montane sub-natural beech-fir forests that had not been logged for more than 100 years to inventory 6 tree microhabitats: carpophores of saproxylic fungi, dendrothelms, cracks, sap flow, cavities and bark loss. We inspected 2183 live trees and 526 snags on 62 plots. Only 0.85 % of the live trees carried carpophores of saproxylic fungi. 78 % of the dendrothelms were found on beech. 89 % of the cracks were observed in fir snags and 68 % of these cases involved bark in the process of peeling. There were 2.1 sap flows per ha and this microhabitat was strictly found on fir. Cavities were the most frequent microhabitat: 57 per ha on average. We found no difference between fir and beech with respect to the microhabitat formed by bark loss. We found one or more girth tree thresholds that correlated to the occurrence of each microhabitat. 81 % of these thresholds were situated above 150 cm of circumference at breast height, which is the logging circumference currently recommended by forest managers for beech and fir. When considering the whole microhabitat set, the most significant girth thresholds were 131, 188, 230 and 280 cm for beech and 312 cm for fir. We suggest conserving several large trees in managed stands.

Differential contribution of post-fire habitat legacies towards beta-diversity components of saproxylic beetles

¹ Ermias Azeria, RNCan

² Jacques Ibarzabal, UQAC & CEF

³ Jonathan Boucher, UQAC & RNCan

⁴ Christian Hébert, RNCan

The attraction of Saproxylic beetles towards recently burned boreal forests is well known. Yet, explaining how variations in post-fire habitats drive beta-diversity patterns remains a central question for both ecology and conservation. A range of indices have been devised to measure different aspects of beta-diversity. We adopted a recently proposed framework that distinguishes the pure “spatial” turnover and nestedness components of beta-diversity, and examine how tree species, gradients in tree size, and burn severities contributed to beta-diversity of saproxylic beetles emerging from tree boles. We simultaneously model both the within- and between habitat classes variation of betadiversity. Our results show that the turnover and nestedness components of beta-diversity of saproxylic beetles are dependent upon different habitat attributes. The turnover component of beta-diversity was primarily explained by tree species, turnover within jack pine as well as between jack pine and black spruce being higher than within black spruce stands. Among tree size classes, turnover was higher among mid-sized trees (12-16cm and 16-20cm) than within smaller (8-12cm) or larger (20-24cm) trees and between them (8-12 vs. 20-24cm). However, the nestedness component of beta diversity was primarily driven by variation in tree size, with highest scores being obtained between the smallest and largest trees, and the lowest scores within and among the largest and mid-sized trees. The two beta diversity components also responded differently to burn severity.

Use of tree cavities by the northern flying squirrel in the eastern Canadian boreal mixedwood forest

¹ Caroline Trudeau, UQAT - Chaire AFD & CEF

² Louis Imbeau, UQAT - Chaire AFD & CEF

³ Pierre Drapeau, UQAM - Chaire AFD & CEF

⁴ Marc J. Mazerolle, UQAT - Chaire AFD & CEF

Tree cavities are used as shelter and breeding nests by numerous avian and mammalian species. In cold environments, tree cavities are often proposed as the best winter nest choice because of the superior protection they offer from precipitation, wind, cold temperatures, and predators. As such, they represent a critical resource that has the potential to limit population size of non-excavating species. The objectives of this study were to assess factors affecting site occupancy in the boreal forest by northern flying squirrels, a secondary user of tree cavities, and to identify which nest type is preferred during the colder days of the autumn-winter period. We trapped flying squirrels twice in 59 aspen-dominated stands in the autumn period to determine site occupancy. A total of 85 individuals were captured on 2880 trap-nights. During the winter, we radio-tracked 26 individuals to 90 diurnal nests in 225 locations. None of the habitat variables considered (cavity availability, woody debris and lateral cover) explained site occupancy. Detectability was influenced negatively by precipitation, and was lower using high traps than low traps. However, uncertainty associated with model-averaged predictions was high. Both females and males used tree cavities (26%), external nests (39%), and ground nests (35%). In cold weather, females preferred ground nests, whereas males preferred external nests. Our results do not support the hypothesis that tree cavities represent a limiting factor to northern flying squirrels in cold environments. Instead, this species seems to be generalist and is opportunistic, using a variety of nest types.

Assemblage composition and diversity patterns on created dead wood in a managed forest landscape

¹ Therese Johansson, Wildlife

² Joakim Hjältén, Department of Wildlife, Fish and Environmental Studies

³ Gibb Heloise, and Environmental studies

Different functional groups of beetles exhibit different responses to forest management and it is essential that we gain knowledge on these responses to minimize the negative impacts of forestry in boreal ecosystems. In a large-scale field experiment, we placed fresh logs in 27 stands in northern Sweden. We tested how saproxylic beetles and functional groups of beetles were affected by substrate characteristics (shaded, burnt and fungi inoculated logs and snags) in different stand types (clear-cuts, mature managed and old-growth stands). We monitored insects on the experimental logs during five years. In all years, substrate characteristics and stand type affected abundance, species richness and assemblage composition. The effect of stand type was stronger than the effect of substrate for most of the examined groups; the clear-cuts differed from the mature managed and old-growth stands, while few differences were detected between mature managed and old-growth stands. The most important substrate effect was the effect of snags, which differed from lying logs in all stand types and years. During early succession on logs, cambium consumers dominated in abundance and had different assemblages on burnt logs compared with control logs. Shading of logs was important on clear-cuts. The results suggest that in an area with intense forestry, both old-growth forest reserves and the creation of a diversity of suitable substrates in managed forests are needed to conserve functionally intact beetle assemblages.

Boreal small mammal, fungi, and insect communities as a function of variation in downed woody debris quantity and quality

¹ Jay Malcolm, University of Toronto

² James Dennis, University of Toronto

³ Alison Fischer, University of Guelph

⁴ Mark Vanderwel, Microsoft Ecology Group

⁵ John Klironomos, University of British Columbia Okanagan

⁶ Jean-Marc Moncalvo, Royal Ontario Museum

⁷ Dave Morris, Ontario Ministry of Natural Resources

⁸ Sandy Smith, University of Toronto

⁹ Ian Thompson, NRCan, Canadian Forest Service

Effects of forest management on downed woody debris (DWD) quality and quantity have the potential to affect the biota of the boreal forest. We used live-trapping of small mammals, fruiting body and DNA-based surveys of fungi on spruce logs, and insect emergence trapping of soil and spruce and aspen logs to study three forest types in boreal northeastern Ontario: mechanized-logged forests 30-40 years old, horse-logged forests 45-65 years old, and unlogged forests. Neighbourhood-scale modeling indicated that in spring, red backed voles were associated with trap stations that had abundant late decay DWD, which was most evident at sites in which this habitat element was scarce (<0.8% projected ground cover), especially horse-logged grids. Fungal sampling revealed strong effects due to sampling method, with 304 species from DNA-based sampling of 60 logs, but only 116 species from fruiting body samples of 150 logs. In both samples, wood decay type was the strongest source of variation (late decay wood had 1.8 times more species than early decay wood). Some members of the Polyporale were most abundant in unlogged sites. Insect sampling also showed strong decay-stage effects. Forest type effects for scelionid parasitic wasps may have been due to less coniferous, late decay DWD in mechanized-logged grids. Preliminary results are presented from studies in which DWD supplies are being actively manipulated.

To burn biodiversity for energy savings:Is deadwood conservation an environmental issue for forest owners?

¹ Philippe Deuffic, CEMAGREF

In their daily practices, forest owners are confronted with environmentally-friendly – but contradictory – discourses. Ecologically-oriented NGOs argue that deadwood should be left in the forest to preserve biodiversity, to provide habitat for small organisms and to maintain soil quality through wood decay. Conversely industrial stakeholders and some public decision makers advocate deadwood harvest to save fossil fuels. Based on a sociological constructionist framework and qualitative interviews, we will first analyze French foresters’ environmental opinions and values and their attitudes towards biodiversity, in particular regarding deadwood conservation. We identify various types of attitudes towards deadwood which could be seen as a waste, a non-profit by-product or a part of the ecosystem. We then study the arguments that make them choose between deadwood conservation and deadwood harvesting for biomass production. On the one hand, they are interested by short-term profitability and pest reduction and on the other hand, they fear potential loss of fertility. Finally, the paper will show that specific approaches to deadwood conservation ought to be negotiated at a local scale, pending further scientific study on biodiversity impacts of deadwood and the development of more positive attitudes toward ecological concerns in the forest owners’ community

Restoring boreal ecosystems using coarse woody debris: an application for oil and gas operators

¹ Matthew Pyper, Alberta School of Forest Science and Management, University of Alberta

² Tim Vinge, Government of Alberta

³ John R. Spence, Alberta School of Forest Science and Management, University of Alberta

Bridging the gap between science and management is a difficult task, but it’s critical that we find ways to successfully do so. In this presentation we will discuss an innovative example that seeks to develop a woody debris field guide for use in restoration projects related to the oil and gas industry in Alberta, Canada. The energy sector in Alberta has been operating on the Boreal landscape for a number of years and has a significant impact on forest resources. Traditionally, disturbances such as seismic lines have persisted for several decades and have failed to recover back to functional forests. Companies now recognize the long-term impact of such disturbances and are seeking innovative ways to restore these ecosystems. Through the use of a literature review, natural analogue curves and our existing knowledge of forest management, we developed recommendations for the use of woody debris in the restoration of these seismic lines. This project not only provides value to the scientific community through performing a review on woody debris with respect to restoration, but also to the practitioner community in the form of a highly visual field guide to implement these scientific concepts on the ground. We will discuss the results from the analysis, and the knowledge exchange process applied to this project.

Response of saprophagous wood-boring beetles (Coleoptera: Cerambycidae) to severe habitat loss due to logging in aspen- and spruce-dominated landscapes.

¹ Michel Saint-Germain, UQAM - Chaire AFD & CEF

² Pierre Drapeau, UQAM - Chaire AFD & CEF

Regional persistence of saprophagous wood-boring beetles (Coleoptera: Cerambycidae) depend on spatial and temporal connectivity between potential egg-laying hosts, i.e., standing dead trees of various decay states. Logging significantly reduces the proportion of late-seral stands in managed boreal landscapes, which results in a decreased availability of standing dead wood. As a result, dependant species may have their abundance reduced or become locally extirpated, potentially affecting the ecosystem processes/services in which they take part. We evaluated the impact of habitat loss on saprophagous cerambycid beetles in two highly fragmented landscapes under different dynamics, the first aspen-dominated, the second spruce-dominated. We expected different responses from the two landscapes, first because species associated with aspen generally uses more decayed wood, second because species associated with boreal coniferous-dominated landscapes are expected to be better adapted to large-scale disturbance, thus of higher dispersal potential. Sixty aspen and 90 spruce snags were dissected for beetle larvae. Species occurrence patterns were related to percentage of residual cover at species-specific spatial scales, identified using iterative regressions done on spatially independent snags. Our results show that some saprophagous wood-borers do react negatively to habitat loss, but that within a relatively homogenous group the response can vary significantly between species. They also show that the spatial scale at which species respond vary significantly with the species life history. Saprophagous wood-borers should be considered potentially sensitive to habitat loss, and their response to fragmentation remains to be evaluated on a longer time frame.

Harvest of bioenergy wood and effects on wood living insects

¹ Mats Jonsell, Dept of Ecology, SLU

To substitute fossil fuels, new assortments of wood are harvested as bioenergy, assortments formerly retained in the forest. Hitherto the main source in Scandinavia are logging residues: branches, twigs and tops, but over the last years interest has expanded to stumps. Extraction of more wood from the forest infers less habitat for organisms breeding in dead wood. However, the fauna in these types of wood is vaguely known and therefore we asked: Is this wood used by species threatened by forestry? Is it necessary to formulate recommendations to mitigate negative effects on the wood- living insect fauna? Can recommendations be based on tree species and diameter classes? Data was collected by bringing in wood samples to the lab and rearing out insects from them. Two age-classes of wood were investigated- one summer old wood and 4-5 year old wood. We found that both logging residues and stumps, retained on clear cuts, may host many species, including several red-listed. Deciduous wood was richer than coniferous especially for logging residues. Therefore we recommend that spruce can be harvested to a large extent, whereas deciduous wood, especially aspen and oak, should be retained on many areas. Diameter cannot be used for recommendations for logging residues, and probably not for the stumps either.

Habitat and substrate associations of red-listed saproxylic beetles in old growth reserves and managed forests: implications for conservation

¹ Joakim Hjältén, Department of Wildlife, Fish and Environmental Studies

Forestry management in Fennoscandia has become a serious threat to biodiversity, particularly threatened are species depending on coarse woody debris (saproxylics) and old growth forests. Thus, the Swedish environmental goals include the protection of remaining forests with high conservation values as well as increasing the amount of dead wood in the forest landscape. However, the relative importance of protected old growth forest areas is debated and our knowledge of habitat and substrate requirements of threatened saproxylic species is limited. To increase our knowledge, we conducted a large scale field experiments at 10 localities, each consisting of three forest types, old growth forest reserve, mature managed forest and clear-cut, in Northern Sweden. We determined the distribution of red-listed saproxylic beetles on standardised experimental substrates of spruce and birch in managed forests and reserves. During the 2001-2006 year we collected and identified ca 360 000 beetle individuals belonging to more than 930 species and of these there were ca 50 red-listed saproxylic species. Somewhat surprisingly, the abundance and species richness of red-listed species was similar in reserves and mature managed forest but lower in clear-cuts. However, the assemblages differed between the forest types, even between old growth forests and mature managed forests as well as between different dead wood substrates. Some species were clearly confined to older forest whereas others only occurred in clear-cuts. The implication of our results for the conservation of threatened saproxylic species is discussed.

Are forest remnants in managed landscapes of the Eastern Canadian boreal forest suitable breeding habitats for cavity nesting birds?

¹ Ugo Ouellet-Lapointe, UQAM - Chaire AFD & CEF

² Brian Harvey, UQAT - Chaire AFD & CEF

³ Pierre Drapeau, UQAM - Chaire AFD & CEF

In Canada’s boreal forest, even-aged management has resulted in extensive landscapes of aggregated clearcuts. Regenerating clearcuts that lack mature trees are generally considered unsuitable habitat for most forest birds. Mature forest cover in these landscapes is maintained through variable retention strategies that range from single tree retention in clearcuts to habitat patches or remnant forests mostly concentrated in linear strips (either cut-block separators or riparian buffers). Such habitats may be used as movement corridors, or for foraging and nesting by some forest dwelling species. We conducted a study on woodpecker nesting activity that assessed cavity occupancy, nesting success and productivity in linear remnants of forests in managed landscapes and compared these parameters with those of breeding woodpeckers in continuous unmanaged landscapes. We found nesting activity for most species in linear remnant habitats. Nesting success and productivity were comparable to continuous forest tracks. These results suggest that linear remnant habitats in even-aged managed landscapes provide quality habitats for woodpecker species, a clear indication of their conservation value. Consequently, we recommend that no further harvesting be conducted in these remnant forests and that they should be maintained as permanent retention habitats in even-aged managed landscapes

Modeling dead wood dynamics to predict effects of biomass harvesting for energy production

¹ Thomas Ranius, Dept. of Ecology, Swedish University of Agricultural Sciences

² Johan Allmér, Swedish University of Agricultural Sciences

³ Alexandro Caruso,

⁴ Anders Dahlberg,

⁵ Mats Jonsell, Dept of Ecology, SLU

⁶ Mattias Jonsson,

⁷ Tomas Hallingbäck,

⁸ Jörgen Rudolphi,

⁹ Göran Thor,

In Sweden, stumps and fine woody debris (FWD) left after clear cutting are increasingly being extracted for bioenergy purposes. We have estimated how extraction of FWD and stump harvest effects habitat availability for about 600 species of wood- and bark-inhabiting basidiomycetes, beetles and lichens in Sweden using Norway spruce (the most abundant tree species in Sweden) as their primary substrate. We combined modeling of (i) the amount of various types of woody debris available throughout a forest rotation in managed forests with (ii) a classification of each species’ associations with different types of wood. The modeling of woody debris was done by equations that describe forest growth, tree mortality, natural decay of dead wood, and destruction and removal of dead wood during forestry operations. We found that extraction of FWD generated a 35–45% reduction in aboveground FWD and a more than 20% decline in the potential amount of substrate for about 50% of the species. The current situation in Sweden with extraction of 70% of Norway spruce FWD on 50% of the clear cuts probably constitutes a minor contribution to the regional extinction risks. Stump harvest has a stronger effect. The volume of dead wood removed per forest area is smaller in comparison with when FWD is extracted, but for Norway spruce, stumps constitute an important substrate for a larger number of species than FWD.

Restoration fire and wood-inhabiting fungi in a Swedish Pinus sylvestris forest

¹ Jörgen Olsson, Department of Wildlife

² Bengt Gunnar Jonsson, Fish and Environmental Studies

A growing awareness of the negative consequences of efficient fire prevention in boreal Fennoscandia has resulted in an increasing use of fire as a restoration method. The primary purpose of restoration fire is to recreate features of natural forests that have been lost during long periods of fire suppression. We used the occurrence of fruiting bodies from wood-inhabiting fungi to assess the conservation value of and gain ecological information about restoration fire in a Pinus sylvestris dominated forest. The general pattern for the majority of the species was a drastic decline during the first two years after the restoration fire. However, our results clearly demonstrate that most of the species that declined during the first years after the fire rebounded after four years and were frequently found on charred wood. Species that increased after the fire and often occurred on charred logs were: Antrodia sinuosa, Botryobasidium obtusisporum, Galzinia incrustans, Phlebia subserialis and Tomentella spp. In addition, three threatened, red-listed and fire-favored species were also found on heavily charred logs: Antrodia primaeva, Dichomitus squalens and Gloeophyllum carbonarium. Our results indicate that fire disturbance creates a unique type of dead wood important for fungal species richness. The results also support the use of restoration fires in maintaining forest biodiversity.

Climate change mitigation: Potential effects of future plantation management on beetles associated with deadwood

¹ Stephen Pawson, School of Animal Biology, Scion

² Antoine Brin, University of Toulouse

³ Hervé Brustel, EI Purpan

⁴ Hervé Jactel, University of Toulouse

A major component of proposed climate change mitigation strategies is the greater use of wood products as a feedstock for bioenergy. Ultimately, increased land use intensity, e.g., stump removal and complete tree harvesting, may be detrimental to biodiversity. We tested the impact of increasing harvest intensity and clearfell age on saproxylic beetle diversity at a landscape scale. Clearfell age was included to assess whether those habitats acted as ecological traps whereby saproxylic beetles were destroyed during site preparation for replanting. The study was undertaken in Pinus pinaster forests in the Landes region of France. Beetle communities were sampled by flight intercept trapping in multiple replicates of model landscapes (radius of 3km) that had differing proportions of recent clearfell, young regenerating and mature stands. Assemblages of saproxylic beetles species in clearfells were distinct from assemblages in mature stands. This may reflect those habitats provide a large amount of specific resource (sun-exposed woody debris and stumps) compared to mature stands. The cumulative number of species was significantly higher in clearfell compared to recently planted stands, suggesting that clearfells may represent ecological traps when deadwood is destroyed prior to the emergence of saproxylic species. The degree of fragmentation of mature forest had a significant effect on the composition of saproxylic beetle assemblages. Furthermore, the species richness of saproxylophagous species in mature stand was significantly higher in landscapes containing the lowest proportion of open habitats. The latter may therefore act as a barrier to dispersion for some forest specific species.

Post-harvest recovery of coarse woody material and its influence of litter dwelling arthropods

¹ Timothy T. Work, UQAM - Chaire AFD & CEF

² Simon Paradis, UQAM - Chaire AFD & CEF

³ Suzanne Brais, UQAT - Chaire AFD & CEF

Recovery of residual biomass following forest harvesting has been proposed as a viable means of obtaining additional fiber for multiple uses. Here we report on the initial responses of leaf litter invertebrates [spiders and carabid beetles] from a series of experimental manipulations of deadwood where residual coarse woody material (CWM) and branches were removed following clear cut and partial cut harvesting in jack pine stands in western Québec. These experiments were put in place in 2008-2009, north of LaSarre, QC and in the Lac Duparquet Research and Teaching Forest. We compared changes in overall insect composition to changes in residual volumes of CWM following experimental removals and examined changes in abundance and sex ratios of individual species. Initial comparisons of beetle and spider communities in LaSarre following biomass recovery in clearcut stands show few differences in compositional changes when compared to clear cut sites without additional biomass recovery. However, individual species such as Agonum retractum did show significant declines as a result of biomass harvesting. We also link arthropod responses from biomass removal studies to a series of partial thinning trials meant to augment CWM as a means of deadwood restoration.

Estimating species loss of saproxylic insects under scenarios of reduced coarse woody material (CWM) in eastern boreal mixedwood forests

¹ Timothy T. Work, UQAM - Chaire AFD & CEF

² Annie Hibbert, University du Québec à Montréal

Increased exploitation of forests and residual biomass has the potential to reduce biodiversity particularly of saproxylic organisms. We compare incidence-based species accumulation curves based on saproxylic flies collected using in situ emergence cages in 2006 and 2007 under two biomass harvesting scenarios. In these scenarios volume-based biomass targets would be achieved by either 1) selective removal of the largest individual pieces of coarse woody material (CWM) or alternatively 2) selective removal of smaller pieces of CWM with preferential retention of larger pieces of CWM with presumably greater conservation value. We then extrapolated a species accumulation curve to estimate thresholds of potential species loss as a function of CWM volume left within a forest stand using binomial mixing. More species would be maintained under the scenario that selectively targets larger individual pieces of CWM because of extremely large species turnover between individual sample logs and little relation between species richness and diameter of CWM. Given these circumstances, the number of individual pieces of CWM present in a stand may be more important in determining species richness than total volume of CWM for flies. When the species accumulation curve was extrapolated to stand-level volumes, species richness began to decline when CWM volumes were reduced below 40 m3/ha. We suggest that intensive management strategies aimed at recovering additional woody biomass should not exploit CWM volumes below these thresholds without mitigative measures if maintaining biodiversity is an objective.

Post-fire variation of coarse woody debris in oak-pine Mediterranean forest

¹ Thomas Fournier, Paleoenvironments and Chronoecology (PALECO EPHE

² Christopher Carcaillet, UMR5059

Wild fire is the most important disturbance in Mediterranean ecosystems acting on plant communities both in terms of diversity and structure. With time since last fire, Alepo pine (Pinus halepensis), which is sustained by wildfire, appears to be substituted by oaks (Quercus ilex; Q. pubescens) leading to a drop in pine numbers and biomass. Here, we test the effect of time since last fire, which alters the plant community, on the load of woody debries (WD). Tree species' dynamics should trigger the structure of the WD. The sampling design is based on Mediterranean woodlands with differing time since last disturbance: 50, 75, 85, 95 and 130 years. The date of the last disturbance was determined by the age structure of Aleppo pine populations. Coarse and fine WD was sampled according to size classes and, characterized in terms of stump, snag and log. Results show that the maximum of Aleppo pine biomass was found in plots with shorter time since the last disturbance (<75 years, which are also characterized by lower CWD). The amount of pine decreases in older plots and the CWD is inceases until the 130 year-old stand. The high value of CWD in the oldest plots is correlated to the drop in pine numbers and biomass. Fine WD tends to increase all along the chronosequence. The hazard of fire spread should increase up to 130 years after the zero event.

Saproxylic beetle assemblages on low stumps, high stumps and logs: Implications for ecological effects of stump harvesting

¹ Jon Andersson, Department of Wildlife, Fish and Environmental Studies

² Joakim Hjältén, Department of Wildlife, Fish and Environmental Studies

A range of conservation measures, based on legal demands or certification requirements are implemented in today’s forestry. One potential drawback in the conservation work are new management plans, which not only include the harvesting of tree stems, branches and twigs, but also low stumps that were earlier left to decay in situ after cutting operations. However, our knowledge of the role of low stumps as habitat for saproxylic organisms is sparse to say the least. The aim of this study was therefore to determine, quantitatively, the extent to which low stumps are utilized by saproxylic beetles and whether the beetle assemblages in low stumps are similar to those of other dead wood substrates (i.e. high stumps and logs). The sampling was conducted at 10 clear-cuts in northern Sweden with emergence traps. No significant differences in beetle abundance or species richness were detected between substrate types. However, there were clear differences in assemblage composition between all substrate types. Our results suggest that low stumps created at final felling support as many species and individuals per volume dead wood as other dead wood substrates and that they are therefore overlooked as substrates for wood living organisms. Consequently, harvesting of low stumps might have negative effects on the diversity of saproxylic beetles, as up to 80% of the dead wood remaining on clear-cuts is in the form of low stumps.

Tree mortality patterns in Picea mariana forests during break up stage in two regions of boreal Quebec.

¹ Nicolas Fauvart, UQAM - Chaire AFD & CEF

² Alain Leduc, UQAM - Chaire AFD & CEF

³ Yves Bergeron, UQAT - UQAM - Chaire AFD & CEF

During stand development, transition between mature and old-growth forest is characterized by augmentation of mortality of dominant and co-dominant trees which are established after a large perturbation. These induce notably an augmentation of dead woods, diminution of merchantable volume of wood which could affect forest management and modification of stand structure by the recruitment of new stems in the canopy. However, characterization of mortality patterns especially during break up stage is still scare. In this study we examine the temporal variation of mortality along a chronosequence of 100 years in two regions whose differ by their soil, climate and perturbation dynamic. Twenty seven stands between 100 and 200 years old on clay and till in Abitibi and northern Lac Saint-Jean were sampled. The year of death was cross-dated on 940 discs from logs and snags and potential cause of mortality were noted (e.g. senescence, wind). We expect that disturbance agents like spruce budworm outbreak or windthrow will cause episodic mortality events on an otherwise, when mortality is induce by senescence, mortality patterns will be asynchronous and continuous. Moreover, we expect that pattern of mortality will be more condensed in rich soil comparatively to less rich soil. These results imply that regional specificities have to be considered in forest management. Furthermore, development of adapted sylvicultural practice that is inspired of this mortality patterns is necessary to maintain integrity old-growth forest into managed landscape.

Recently dead merchantable stems from the boreal forest of Québec

¹ Julie Barrette, Laval University

² David Pothier, Laval University

³ Isabelle Duchesne, FPInnovations-Forintek Division

⁴ Nancy Gélinas, Laval University

Recently dead, merchantable stems frequently do not show signs of decay under the bark. Besides its important ecological role, it can be used by the forest industry, but this raises many questions related to wood quality. In the public forests of Québec, recently dead merchantable stems been added to the annual allowable cut as an offset for the drastic reduction in the allocation in live wood. Due to the long intervals between natural fires, the boreal forests of Québec’s North Shore region are characterized by important volumes recently dead merchantable stems that may have a significant impact on the economic viability of the industry. To help forest industries plan their activities, this project was designed to: i) determine the temporal variation of standing recently dead merchantable stem volume through a chronosequence after fire; and ii) compare volume recovery, lumber value, lumber strength and stiffness of two states of wood decomposition based on Hunter’s classification (decay stages 3 and 4) and live trees. Our results showed that pre- and post-disturbance, recently dead merchantable stems tend to follow a pattern similar of that of coarse woody debris. They also indicate that one thousand board feet (approx 2.4 m3) of lumber produced from Hunter's class 4 trees is worth CAD $48.69 less than if it was produced from live trees. It may be preferable to avoid harvesting trees from this stage of decomposition.

Dead wood diversity and their decay-class dynamics in the northwestern boreal black spruce forests of Quebec

¹ Chafi Chaieb, UQAM - Chaire AFD & CEF

² Nicole Fenton, UQAT & Chaire AFD

In unmanaged boreal forests standing dead trees and coarse woody debris are an important component of stand structure, but knowledge on their quantities and dynamics in the boreal black spruce Picea mariana (Mill.) BSP forest is limited. To determine the influence of time since last fire (TSF) on the abundance of standing dead trees in old-growth black spruce forest and to explain the diversity of the diameter structure of snags and the diversity of decay classes of coarse woody debris, 129 pure black spruce stands, based on maps derived from forest inventories, were sampled in an area of over 14 000 km2 in Abitibi, Quebec. Data include measurements of age structure, coarse woody debris volume, number of snags and several environment variables. A multimodel analysis proves that TSF and stand origin were the two variables that best explained the variability in the abundance of standing dead trees. However, a comparison of the snag abundance among three age classes (mature, overmature, old-growth forest) did not indicate any significant differences. Nevertheless, multinomial analysis indicated a greater likelihood of having a high snag abundance in overmature stands (120 to 180 years TSF). Overmature stands were also significantly richer in coarse woody debris (volume and abundance) then the youngest and the oldest stands. They also had the most diverse snags and coarse woody debris diameter structure. Unmanaged overmature forests must be preserved to ensure better availability of dead wood in the landscape.

Insect succession in postfire black spruce forests: a 10-year study

¹ Christian Hébert, RNCan

² Ermias Azeria, RNCan

³ Georges Pelletier, Natural Resources Canada - Canadian Forest Service

⁴ Michel Saint-Germain, UQAM - Chaire AFD & CEF

⁵ Pierre Drapeau, UQAM - Chaire AFD & CEF

Fire is the most important natural disturbance affecting the dynamics of black spruce boreal forests. Within the context of wood fibre rarefaction, salvage harvesting of recently fire-killed trees in the boreal forest is a measure that helps to maintain the wood volumes needed to support industrial activities. However, a diverse insect fauna is found in burned trees and needs to be taken into account in order to avoid negative impacts of salvage harvesting on biodiversity. We studied insect succession in black spruce trees that died after a fire that occurred in early June 1999 in the Parc des Grands-Jardins, Quebec, Canada. Four trees were cut yearly from 2000 to 2004, and again in 2009, in each of three burned mature stands; 40-cm boles were then collected and reared for up to four years. In 2005, bole sections were also collected from trees cut in previous years to study insect succession in trees that fell to the ground. Results indicate that snags are rapidly colonized by several species of Cerambycidae and Scolytinae. Snags were heavily used during the first two years after fire but they became poorly used after, except by some species such as Acmaeops pratensis (a red-listed species in Europe) that increased over time. The latter species was still found in snags 10-yrs after fire. Once on the ground, boles were invaded by a variety of insects, predominantly by ants but also by several saproxylic species.

Diversity of bryophytes in relation to available coarse woody debris: does it differ between a post-fire and a post-clearcut forest succession?

¹ Myriam Paquette, UQAT - Chaire AFD & CEF

² Nicole Fenton, UQAT & Chaire AFD

³ Yves Bergeron, UQAT - UQAM - Chaire AFD & CEF

⁴ David Pothier, Laval University

In the boreal forest, numerous bryophyte species are associated with downed logs and stumps as substrate but also for the fine scale humidity and light conditions they create. Managed forests differ from natural forests in the availability of dead wood as well as in the heterogeneity of available microhabitats for bryophyte colonisation. This study compared the amount of available coarse woody debris (CWD) in function of decay class and diameter in a post-fire and a post-clearcut forest succession. Secondly, the diversity of bryophytes was related to CWD amount by decay class, disturbance type and time. The study area is located in the North Shore region of the province of Quebec, Canada, in the balsam fir-white birch and spruce-moss forest domains. Eighteen sites, nine after fire and nine after clearcut, ranging in age from 20 to 80 years post-disturbance were sampled. All CWD in a 400 m2 circular plot, one per site, was measured and categorized as belonging to one of five decay classes. Bryophytes were collected within 20 subplots of 1 m2 and their associated substrates were noted. CWD volume is predicted to be higher in the post-fire chronosequence, and they will support a more diverse and abundant epixylic bryophyte community. However, as bryophytes are dispersal limited, time as well as microhabitat availability is predicted to be an important factor in determining bryophyte colonisation on CWD.

Mortality and dead wood dynamics following forest tent caterpillar outbreaks in aspen stands: A model for partial cutting?

¹ Benoît Gendreau-Berthiaume, University of Alberta

² Brian Harvey, UQAT - Chaire AFD & CEF

³ Daniel Kneeshaw, UQAM - Chaire AFD & CEF

Forest tent caterpillar (FTC) is an important insect defoliator in boreal mixedwoods. Vast areas of aspen-dominated forests in eastern and central Canada have recently been subject to dieback and mortality following FTC outbreaks and/or drought. This study evaluated when mortality occurred around a FTC outbreak (1999-2002) in three aspen-dominated stands in Abitibi, Quebec. We also compared patterns of mortality and maintenance of standing dead wood following FTC outbreaks to light low thinning and heavy crown thinning treatments preceding the outbreak (winter 1998-99). To estimate time of death in FTC affected stands, we sampled disks and cross-dated chronologies from dead trees in 2009 with a reference chronology. Snag diameter distributions were calculated for low and high degradation snags (classes 4-6 and 7-8 respectively, according to Imbeau & Desrochers’ (2002) classification). In stands affected by FTC, smaller stems died first with 35% and 62% of the dead stems < 17cm DBH dying before or during the outbreak respectively, while 24%, 39% and 37% of dead stems ≥17 DBH died before, during and after the FTC outbreak respectively. Stands affected by the FTC maintained higher densities of both high and low degradation snags compared to partially harvested stands, especially in diameter classes over 20cm. However, both partial cut treatments maintained large living aspen stems, thus providing for potential recruitment of large snags in the future. Finally, FTC had more of a low thinning effect, thus showing greater resemblance to the light low thinning treatment.

Short-term responses of beetle assemblages to wildfire in a region with more than 100 years of fire suppression

¹ Therese Johansson, Wildlife

² Jon Andersson, Department of Wildlife, Fish and Environmental Studies

³ Joakim Hjältén, Department of Wildlife, Fish and Environmental Studies

⁴ Mats Dynesius, Swedish University of Agricultural Sciences

Suppression of wildfires in boreal landscapes has become widespread and has seriously affected many species. Little is however known about the response of organism assemblages to large wildfires in regions with a long history of effective fire suppression, such as Scandinavia. We studied the short-term effects of a >1600 ha wildfire on saproxylic beetle assemblages in northern Sweden. For two years after fire, beetles were sampled in 12 sites using large window traps, half in old pine forest stands in the burned area and half in similar, but unburned control stands. The entire beetle assemblage and seven subgroups were analyzed: saproxylics, fire favoured, strongly fire favoured, fungivores, predators, cambium consumers and red-listed species. Species composition differed between burned and unburned forests in all groups. Beetle abundance was higher in the burned area for the entire assemblage and for saproxylics, including both groups of fire favoured species, predators and cambium consumers. In contrast, species number was higher only for non-saproxylics, strongly fire favoured species, and cambium consumers. Our results show that wildfire has rapid and strong effects on a wide range of beetles. However, we trapped very few fire dependent beetles, which may suggest a lack of such species in the region, possibly due to >100 years of fire suppression. At the regional scale, the studied wildfire potentially increases the abundance of these beetles after a longer period of reproduction in the burned area.

Deadwood and fine litter dynamics following complete and partial harvesting

¹ Manuella Strukelj, UQAT - Chaire AFD & CEF

² Suzanne Brais, UQAT - Chaire AFD & CEF

Forest ecosystems play an important role in the global carbon cycle. It is expected that a shift from a single even-aged management approach towards an approach based on varying silvicultural treatments may have implications for forest C balance. Our objective was to compare the effects of harvesting prescriptions on finelitter and coarse woody debris (CWD) dynamics. The study was set in the SAFE Project, an experiment within the Lake Duparquet Research and Teaching Forest that tests an ecosystem management model based on natural dynamics. This project includes different harvesting prescriptions in three stands (aspen, post-budworm and mixed-aspen stands). At various intervals after harvesting, the following were assessed: leaf litterfall by means of litter traps; volume of CWD by triangular-transect method, finelitter and wood decomposition rates by litterbags experiment. In all stands, litterfall decreased after harvesting, reflecting residual basal area, whereas the amount of CWD, mainly small fresh debris, increased. Differences between treatments decreased with time. After 8 years, litterfall and amount of CWD showed little difference between partial harvesting and control. Treatments had no significant effect on rates of decomposition of wood blocks. However, mass losses of leaf litterbags were slightly lower in clearcut of aspen and post-budworm stands. In future, carbon pools in soils will be estimated and compared with differences between carbon inputs by litterfall and CWD recruitment and carbon outputs by decomposition in order to establish a model of carbon dynamics in boreal forest in a context of ecosystem management.

Patterns of tree mortality after partial cutting in northern hardwood stands along an ecological gradient: implications for deadwood recruitment

¹ François Guillemette, Quebec Ministry of Natural resources and Wildlife

² Marilou Beaudet, Quebec Ministry of Natural resources and Wildlife

Management of northern hardwood stands under the selection system raises concerns about the possible development of a scarcity of deadwood over the long term because of recurring stand improvement associated with harvest performed approximately 20-years or so. To address this issue, we studied dead tree recruitment 10 years after partial cutting (25 to 35% basal area) in 280 stands across southern Quebec. Recruitment of large dead trees (diameter at breast height > 29 cm) was 1.1 ha-1 yr-1 in treated stands, which is 40% lower than in untreated stands. This amount varied significantly among ecological regions. More than half of dead trees were found dead standing (snags), while others were wind-broken or uprooted. Tree-level mortality probabilities were modelled to test the significance of some tree-level, stand-level and environmental variables. On one hand, tree-level variables, such as species identity and a risk-product classification, were strongly associated with the probability of becoming a snag. Although the highest quality trees were three to five times less likely to become snags than damaged trees, they still had a considerable probability of becoming snags (1.1 to 1.6% 10 yrs-1). On the other hand, environmental variables, such as mean annual temperature and longitude, were strongly associated with the probability of a tree dying from wind-related causes (stem breakage or uprooting). Wind-related tree death was more likely in western regions with higher temperatures. Overall, our results indicate the presence of different regional dynamics of tree mortality, which has regional implications for deadwood recruitment and forest management.

Interactions between logging and fire : their effects on the dynamics of a keystone primary excavator in the Eastern boreal forest of North America.

¹ Antoine Nappi, Direction du développement stratégique, Bureau du forestier en chef

² Pierre Drapeau, UQAM - Chaire AFD & CEF

The black-backed woodpecker (Picoides arcticus) is considered a fire specialist throughout its breeding range. Given its high abundance in recent burns, it has been hypothesized that these habitats may be source habitats for this primary excavator. We conducted a 3-year post-fire study in high-severity burned black spruce forests that varied in pre-fire age in central Quebec, Canada. Our objectives were (1) to evaluate the occupancy and reproductive success of black-backed woodpeckers and (2) to examine factors involved in the selection of cavity snags and nest site selection. Pre-fire forest cover conditions were an important component of the quality of black-backed woodpecker’s nesting habitat. Reproductive success was higher in areas with high proportions of burned late-seral forests than in areas dominated by burned early-seral stages. Burned forests likely functioned as source habitats for the first two years following fire, although this status varied with pre-fire forest age. Post-fire forests may thus significantly contribute to black-backed woodpeckers population levels. Current forest management which reduces late-seral forest cover can affect, however, the quality of post-fire habitats important to the black-backed woodpecker and other cavity users.

The effect of forest management intensity on the diversity of wood-decaying fungi and dead wood decomposition (FunWood)

¹ Tiemo Kahl, Institute of Silviculture, University of Freiburg, Germany

² Bjoern Hoppe, University of Freiburg

³ Tobias Arnstadt, Department of Environmental Biotechnology

⁴ Dirk Krueger, Helmholtz Centre for Environmental Research - UFZ

⁵ Martin Hofrichter, Helmholtz Centre for Environmental Research – UFZ

⁶ Jürgen Bauhus, University of Freiburg

Dead wood is decayed by various types of organisms such as insects, bacteria and fungi. Fungi, chiefly Basidiomycota and a few Ascomycota, play a dominant role. We will show the change in dead wood fungal diversity on logs of Fagus sylvatica, Picea abies and Pinus sylvestris along a forest management intensity gradient in Germany and its correlations with wood decay and ecosystem processes such as nitrogen cycle and organic carbon leaching. Most studies on dead wood decomposition have focused on old growth forests (primeval forests), where large amounts of dead wood are available. However, whether the decomposition patterns in dead wood are altered through patterns in fungal colonization that are related to forest management (intensity, landscape context) has not been investigated so far. We hypothesize that the diversity of wood decaying fungi increases with decreasing forest management intensity. In terms of ecosystem processes we hypothesize that wood decomposition rates as well as the degree to which wood is completely mineralized increase with fungal diversity. An alternative hypothesis to the latter is that in cases where wood decomposition is dominated by a few aggressive fungi e.g. Fomes fomentarius the wood decay rates are accelerated or in the case of Xylariaceae such as Xylaria spp. or Ustulina spp., a substantial part of dead wood is chemically transformed into persistent melanins, which may form a carbon sink in forests.

Deadwood recruitment and its spatial distribution in unmanaged and selection harvested stands of a mixed forest in northern Japan

¹ Sayoko Naito, Department of Forest Science, Hokkaido University

² Toshiya Yoshida, Graduate School of Environmental Science, Kyoto University

³ Futoshi Nakamura, Hokkaido University

It’s important to examine not only the amount of deadwood but also how they are spatially distributed in natural forests, and to evaluate effects of management on them. The objective of this study is to compare deadwood recruitment and its spatial distribution in unmanaged and harvested (single-tree selection cutting) stands of a fir-dominated mixed forest in northern Hokkaido, Japan. Tree inventory datasets, based on an all tree census (>= 12.5 cm in DBH) at approximately 10-year intervals, have been recorded over 30 years in an unmanaged stand (5.4 ha) and a harvested stand (6.7 ha). All trees were stem-mapped with individual identification in these stands. Spatial distribution patterns of deadwood were evaluated with Ripley’s L function. The amount of deadwood recruitment during the study period in the unmanaged stand was higher than that in the harvested stand. In terms of size distribution, small trees (DBH =< 20 cm) in the harvested stand had higher mortality than that in the unmanaged stand. On the other hand, the supply of larger dead trees (DBH >=25 cm) was greater in the unmanaged stand. The spatial patterns of deadwood recruitment in the unmanaged stand exhibited a clumped distribution at scales between 20-60 m throughout the study period, while that in the harvested stand tended to shift to random distribution at scales larger than 20 m. These results suggest that tree harvesting has altered the spatial pattern of deadwood recruitment and reduced structural complexity of the harvested stand.

Distribution of wood-boring beetle damage in fire-killed black spruce (Picea mariana) in the boreal forest of Northern Quebec.

¹ David J. Gervais, UQAM - Chaire AFD & CEF

² David F. Greene, Concordia University & CEF

³ Timothy T. Work, UQAM - Chaire AFD & CEF

Fires in the boreal forest generate unique habitats that are quickly colonized by saproxylic coleoptera that utilize newly available dead or moribund trees to feed and reproduce. Several of these colonizing species produce larvae that feed on the phloem in the first instars before entering the xylem where they excavate deep galleries to complete their development (families Cerambycidae, Buprestidae and Curculionidae, genera Scolytinae). Recent studies show that the pattern of wood-boring beetle damage is not homogeneous throughout the landscape; some trees display high rates of attack, with several hundred entry holes within the first meter of tree trunk whereas others show very little or no damage. Although several environmental factors have been related to the observed heterogeneity, none can conclusively describe the pattern. We evaluated the relationship between fire severity/intensity, tree size, elevation and the landscape-scale distribution of beetle damage in black spruce. Sampling was carried out over the summer of 2007 in four 2-year old fires north of Chibougamau in Northern Quebec. Damage was quantified in 749 trees by counting entry holes within the first 1.5 meters of tree trunk. Results showed that beetle damage increased with fire intensity, tree size and elevation. Results are discussed within the framework of post-fire salvage logging management and industry standards for the grading of beetle damaged lumber.

Accounting for dead wood (debris and snags) characteristics and quantity in managed stands : a comparison of selection cut (SC) and 2 diameter cuts (SC) in Sugar Maple/Yellow birch stands of Témiscamingue

¹ Jérémie Poupart Montpetit, UQAM - IQAFF - CEF

² Frédérik Doyon, UQO - IQAFF & CEF

³ Yves Bergeron, UQAT - UQAM - Chaire AFD & CEF

Large woody debris provides many ecological services, forming high quality substrate for the establishment and support of multiple species. In unmanaged forests, dead wood is continuously recruited through the mortality dynamic of old and less vigorous trees. In the deciduous temperate forest, diameter limit cut (DLC) or selection cutting (SC) are often used to manage stands. In harvested stands under such partial cutting systems, large (DLC) or less vigorous trees (SC) are culled, which can limit the recruitment and quality (size and decay state) of dead pieces. This study aims at documenting the characteristics (size and decay state) and the abundance (volume and density) of dead wood (downed woody debris (DWD) and snags) in Sugar Maple/Yellow Birch stands of Témiscamingue, south-western Québec, harvested using diameter limit cut in 1980 (DLC80, selective cut) and in 1990 (DLC90, non-selective cut) and selection cut in 1990 (SC90). DWD and snags from 15 stands (5 stands/treatment, 4 sites/stands) were sampled using prism sweep, noting diameter, decay state and length. Our results show that volumes of DWD (CDL80, 57.74, CDL90, 69.3, CJ90, 56.4 m3/ha) and snags (CDL80, 15.8, CDL90, 17.9, CJ90, 23.9 m3/ha) are similar among the treatments and all lower than what was observed in unmanaged forests of this type in the literature. Snag abundance is significantly higher in SC90 (26.8/ha) than DLC80 (6.8/ha). This is explained by significantly higher snag mean diameter in DLC80 (436 mm) compared to SC90 (318 mm). We also observe significantly more decayed DWD in SC90 than DLC90, and more decayed snags in DLC (80&90) than in SC90. These results suggest that these two silvicultural treatments may impede dead wood recruitment and have different effects on dead wood quality and repartition.

Snags and downed-woody debris in recent and old windthrown and windthrown-salvaged Sugar Maple/Yellow Birch forests of Témiscamingue, Québec.

¹ Frédérik Doyon, UQO - IQAFF & CEF

² Daniel Bouffard, IQAFF

Windthrow is a disturbance that exerts a dominant influence on dead wood dynamics in temperate deciduous forests. Monitoring was implemented to understand the effects of windthrow and subsequent timber salvaging on dead wood. We sampled 35 Sugar Maple/Yellow Birch stands in Témiscamingue, Québec, of which 21 were located in an area windthrown in 2006 (7 windthrown, 7 windthrown-salvaged and 7 stands undisturbed), and 14 others in an area windthrown in 1983 (7 windthrown and 7 undisturbed stands). Snags were described in 400 m2 sample plots and DWD (diameter ≥15.1 cm) using a 90 m line intersect. Snag diameter (36 cm), basal area (11 m2ha-1) and density (78 ha-1) were the highest in the 2006-windthrown plots while almost no snags were observed in the 2006-windthrown-salvaged plots. However, 24 years after the windthrow, snag characteristics in the windthrown plots were not different from the control plots. Small DWD volume was about 2.5 times higher in windthrown and windthrown-salvaged plots (≈75 m3/ha) than in control plots. Although large DWD volume was not different among treatments because of its large variability, it was two times greater in the 2006-windthrown plots (133 m3/ha) than in the others. These results suggest that dead wood dynamics are very fast after windthrow and timber-salvaging reduces the snag pool available for future recruitment to DWD, short-cutting dead biomass cycling.

Population trend of the Rosalia longicorn (Rosalia alpina) in Switzerland

¹ Thibault Lachat, Swiss Federal Institute for Forest, Snow and Landscape Research WSL

Many threatened forest relict species dependent on old trees and dead wood suffer from habitat loss due to logging and wood harvesting. The analysis of historical and current occurrence data (relative sampling) shows a positive trend since 1900 for the populations of the popular saproxylic cerambycid Rosalia alpina in the Swiss forests. Although this species benefited from special conservation efforts and attention in the last years, the tendency started many decades before. This positive trend is ascribed to improved breeding conditions. The larvae of Rosalia longicorn are mainly dependent on old moribund and standing dead beeches that have considerably increased in Swiss forests over the last decades. Furthermore, Swiss forests are getting older and the number of trees with a diameter larger than 80 cm has doubled in the last 20 years. Although, historical data (>20 years back) about dead wood are not available, it can be assumed that with the increase of the forested area, the decrease of forest management intensity and an adapted forestry management, the amount of dead wood in Swiss forests has increased over more than 100 years. Even though quite a long time is necessary for saproxylic species to recover after a period of intensive exploitation and even though other important factors currently show a negative trend (Swiss forests become denser and darker), a primeval forest relict species such as the Rosalia longicorn is shown to be able to recover in surprisingly short time.

The importance of senescent or dead trembling aspen (Populus tremuloides) for cavity nesters along a chronosequence of naturally disturbed mixedwood boreal forests in eastern North America

¹ Philippe Cadieux, UQAM - Chaire AFD & CEF

² Pierre Drapeau, UQAM - Chaire AFD & CEF

³ Louis Imbeau, UQAT - Chaire AFD & CEF

⁴ Antoine Nappi, Direction du développement stratégique, Bureau du forestier en chef

The availability of cavity-trees plays an important functional role in maintaining the biodiversity of forest ecosystems. The overall objective of this project is to better understand the use and selection of nesting trees for forest dwelling cavity nesters along an age gradient of naturally disturbed boreal mixedwood forest stands. Between 2003 and 2010, twelve 24 to 40 ha plots ranging from 61 to 245 years since the last fire were surveyed in the Lake Duparquet Research and Teaching Forest (FERLD) in Abitibi, Quebec, in order to detect cavities with active nests. We present nest webs for mature and old growth boreal mixedwood forest. These are composed of 5 primary cavity excavator species (woodpeckers), two weak cavity excavator species (nuthatches, chickadees) and 7 secondary cavity users (ducks, birds of prey, squirrels). Secondary users have strong links to specific excavators, the Pileated woodpecker (Dryocopus pileatus) cavities being the most exploited resource. Cavity nesting assemblages remained similar throughout the age gradient. However, despite a lower abundance of nests, there was greater complexity in the conifer old-growth nest web. In addition, we show that even in old-growth forests, primary excavators select large diameter trembling aspen (Populus tremuloides) in varying states of decay to excavate their cavity. Although a substantial proportion of cavities were excavated in live aspen trees, most of these trees were infected by fungal heart rot (Phellius tremulae). The presence of senescent or dead large diameter trembling aspen is necessary to maintain cavity-nesting assemblages in mixedwood boreal forests under natural disturbance regimes.

Deadwood cycling in old-growth temperate forests: what are the differences between diverse forest types?

¹ Libor Hort,

² David Janik,

³ Dusan Adam,

⁴ Tomas Vrska, Silva Tarouca Research Institute for Landscape

⁵ Kamil Kral,

⁶ Pavel Šamonil,

⁷ Pavel Unar,

As a result of 35 years research of old-growth temperate forests we present the differences in deadwood volume, structure and decomposition rate between floodplain hardwood and mountain fir-beech forest stands. The objectives of the study were i) to quantify individual forest type cycling and ii) to evaluate the differences between CWD cycling in the two forest types. Both sites have been left to spontaneous development since the 1930s. From 1973 to 2007 three repeated measurements of standing and lying, living and dead trees (DBH ≥10 cm) were performed on the whole area (22+21 ha). The patterns of wood cycling were described and plotted in the form of a flow chart. Specifically the differences in rate of woody biomass cycling and the changes in dead/live volume ratio in time were compared between both forest types. Although the two sites differ significantly in natural conditions and tree species composition, the total volume of live and dead trees reached similar values. However, the rates of living tree woody biomass and CWD cycling differed markedly. The rate in alluvial hardwood forest exhibited a distinctly higher value compared to the cycling rate in mountain fir-beech forest. Over 35 years the dead/live volume ratio in alluvial hardwood forest varied little: it ranged from 0.17 to 0.26. The ratio in the mountain fir-beech forest exhibited more dynamic change: it increased from 0.25 to 0.62.

Metapopulation dynamics and conservation of a beetle, Osmoderma eremita, living in hollow trees in Europe

¹ Thomas Ranius, Dept. of Ecology, Swedish University of Agricultural Sciences

Osmoderma eremita is a beetle species associated with hollow trees, which has been given the highest priority according to the European Union’s Habitat Directive. In managed forests, trees are cut down before they become old enough, and therefore today the species occurs mainly in old-fashioned agricultural landscapes. Based on capture-recapture and telemetric studies, we have estimated that only 15 % of adult beetles leave their natal tree for another tree. This, together with the outcome from studies on spatial occurrence patterns and population dynamics, suggest that O. eremita individuals in each tree may be described as a local population that is fairly independent from the populations in neighbouring trees. Individuals in a stand of trees together form a metapopulation, connected by dispersal between trees. A population viability analysis based on the present knowledge about the species’ population dynamics suggested that many O. eremita populations in small stands will go extinct, even if the habitat quality of these stands are assumed to remain constant. However, the extinctions may take place in several decades or even a few centuries. Larger aggregations of suitable trees are necessary to provide long-term viability of O. eremita populations. Therefore, priority should be given to maintaining the largest sites, or to increase size and connectivity of smaller localities with potential for relatively rapid restoration.

Foraging ecology and use of dead wood by woodpeckers in Eastern Canadian boreal forests

¹ Antoine Nappi, Direction du développement stratégique, Bureau du forestier en chef

² Pierre Drapeau, UQAM - Chaire AFD & CEF

We quantified and compared tree selection patterns, foraging and relative use of dead wood of six bark-foraging woodpeckers - downy woodpecker (Picoides pubescens), hairy woodpecker (Picoides villosus), American three-toed woodpecker (Picoides dorsalis), black-backed woodpecker (Picoides arcticus), yellow-bellied sapsucker (Sphyropicus varius) and pileated woodpecker (Dryocopus pileatus) - in eastern boreal forests of North-America. A total of 266 foraging observation bouts made on more than 700 trees were recorded at three study sites characterized as mixedwood, conifer and conifer-burned. Wood dissection was conducted on a subset of 47 foraging trees used by the four Picoides species to identify potential prey and corroborate foraging tree selection with behaviour. Dead wood represented an important foraging substrate for four of the six species. Woodpeckers were categorized according to their selection for specific stages of tree degradation. The yellow-bellied sapsucker and the pileated woodpecker represented opposite ends of this gradient, being respectively associated with earlier (live trees) and later (degraded snags) tree degradation stages whereas Picoides species occupied intermediate positions on the degradation gradient. Although Picoides species in general made extensive use of dead wood, our results highlight significant differences in species specialization in substrate use, associated wood-dwelling arthropods and foraging behaviour. We emphasize that providing foraging substrates for most woodpecker species in these forests not only requires maintaining dead wood but also considering the underlying dynamics of dead wood (e.g. recruitment and degradation).

3P Sampling of Downed Dead Wood

¹ Mark Ducey, University of New Hampshire

² Jeffrey Gove, USDA Forest Service

The irregular form and decay of downed dead wood presents challenges for the accurate assessment of carbon and nutrient pools. The prism sweep technique of Bebber and Thomas uses a familiar variable-probability approach to sampling downed logs, but its accuracy may be limited by the assumption of Huber’s equation for volume. It also requires measuring the length of tallied logs. We show how 3P (Probability Proportional to Prediction) sampling approaches to timber inventory can be adapted to dead wood inventory. 3P sampling can be used to reduce field inventory costs, and to reduce or eliminate bias associated with Huber’s equation. 3P approaches may also be useful in other variable-probability sampling methods for downed wood, such as point relascope sampling.

Saproxylic beetle communities of trembling aspen deadwood

¹ Charlene Wood, University of Alberta

² John R. Spence, Alberta School of Forest Science and Management, University of Alberta

³ David W. Langor, NRCan

Deadwood is a critical component of forest ecosystems, particularly as habitat for hyperdiverse saproxylic (i.e. deadwood-dependent) communities. Saproxylic beetles comprise a large proportion of forest biodiversity and have received growing attention as many species have become threatened in intensively managed boreal forests of Fennoscandinavia. However, less is known about this fauna for other areas, including North America. We sampled saproxylic beetles from targeted deadwood habitats in mature deciduous stands of the boreal mixedwood forest in northwest Alberta, Canada, using emergence traps, window traps, rearing drums, extraction funnels and destructive sampling. We assessed beetle assemblages from a wide array of deadwood habitats, ranging from declining, intact trees to nearly humified wood on the forest floor and examined habitat associations. We collected 229 saproxylic beetle species, including 5 new species to science. The saproxylic beetle community varied greatly between deadwood habitat types. Position, decay class, and diameter influenced species composition and richness. Numerous species have a strong affinity for a particular decay class and some species were indicators of large diameter deadwood. Forest management schemes should aim to maintain critical deadwood habitats over time, including the full range of decay stages of both standing and fallen deadwood, particularly large diameter wood. Effective conservation of forest biodiversity will require further understanding of the saproxylic beetle fauna, taxonomy, habitat preferences, and responses to harvesting.

Nest site characteristics of the Okinawa Woodpecker Dendrocopos noguchii in the subtropical evergreen forest “Yambaru”; Consequences of land-use history and pine-wilt disease.

¹ Nobuhiko Kotaka, Kyushu research center

² Kazuhiko Saito, Forestry and Forest Products Research Institute

³ Shin Abe, Kansai research center

The Okinawa Woodpecker (OW), is the rarest extant woodpecker species,　and inhabits only subtropical evergreen forests called “Yambaru” located in the northern part of Okinawa Island, south-western Japan. The breeding range of OW has been known to be restricted to primeval forest in the central mountain range of Yambaru. However, breeding was recognized recently outside of this main range. In this study, we conducted a survey of stand characteristics and land-use history of OW nest sites. We examined the OW nest site history by using 8 aerial photos (1944～2006) and forest plan maps, and also a vegetation survey around the individual nest trees. According to the land-use history results, the OW nest sites were classified into 4 categories: 1) primeval or mature forest, 2) secondary forest more than ca 40 years after clear-cut, 3) secondary forest more than ca 40 years after abandonment of farmland and 4) pine (Pinus luchuensis) plantation or pine mixed forest infected by pine-wilt disease. In the category 1) and 2) forests, OW nested mainly in Castanopsis sieboldii, while in the secondary forest of the category 3), Melia azedarach appeared to be the most important nest tree species. OW usually avoids conifer forest, but in this study, we found OW nested on pine snags in pine forests. Infection of pine-wilt disease seems to create temporal nesting habitat for OW.

Morphological attributes and snag classification of four North American boreal tree species: relationships with time since death and wood density

¹ Virginie-Arielle Angers, UQAM - Chaire AFD & CEF

² Yves Bergeron, UQAT - UQAM - Chaire AFD & CEF

³ Pierre Drapeau, UQAM - Chaire AFD & CEF

Degradation classification systems of snags based on external morphological attributes are widely used but are not always significantly related to elapsed time since death or wood density. Furthermore, these classification systems rely on the global aspect of snags, and the predictive ability of specific attributes has rarely been investigated. We determined which morphological attributes best predicted time since tree death (TSD) and wood density in the snags of four major boreal species in eastern North America: trembling aspen (Populus tremuloides Michx.), balsam fir (Abies balsamea [L.] Mill.), jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana [Mill.] BSP). Sampling was conducted in northwestern Quebec, Canada. For each species, 37 to 65 snags were sampled and TSD was determined using dendrochonology. A first set of multiple linear regressions showed that bark cover was the only morphological attribute common to the models of all species and was the sole predictive variable for TSD in balsam fir. In other species, additional predictors of TSD varied. A second set of multiple linear regressions showed that the combination of predictors for wood density was also species-specific and that wood penetrability was a common predictor for all species. This study indicates that compared to classical degradation classification systems, species-specific models built according to significant morphological attributes do not represent more time- or resource-consuming field assessments and provide more precise measurements of TSD and wood density.

Mineralization rates and factors influencing snag decay in four North American boreal tree species

¹ Virginie-Arielle Angers, UQAM - Chaire AFD & CEF

² Pierre Drapeau, UQAM - Chaire AFD & CEF

³ Yves Bergeron, UQAT - UQAM - Chaire AFD & CEF

Mineralization rates (measured as wood density loss) were assessed in snags of four boreal species: trembling aspen (Populus tremuloides Michx.), balsam fir (Abies balsamea (L.) Mill.), jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP). Wood density and variables potentially influencing decay rates (time since death; age; average radial growth; diameter at breast height; Cerambycidae activity, and Scolytinae activity) were measured on discs of 207 snags from northwestern Québec, Canada. Mineralization rates varied significantly among species. Trembling aspen exhibited a more rapid rate of loss than conifers (k = 0.0351). Jack pine was the second most rapid species to lose wood density (k = 0.0152), followed by balsam fir (k = 0.0094). Black spruce was particularly resistant to mineralization (k = 0.0065). Time since death coupled with Cerambycidae activity was associated with lower wood densities in trembling aspen, balsam fir and jack pine, whereas slower growth rates and smaller diameters were associated with a decreased mineralization rate in black spruce. We suggest that stand environmental conditions could explain why time since death has less influence on black spruce wood decay.

Buried wood – or the role of bryophytes in the deadwood cycle of humid boreal forests

¹ Ulrike Hagemann, Institute of Soil Science and Site Ecology

² Martin T. Moroni, Forestry Tasmania

³ Johanna Gleißner, Geo and Hydro Sciences

⁴ David W. Beilman, Dresden University of Technology

Using triangular line intersect sampling (trenching), large amounts (389±39 m3 ha-1) of buried wood were found in the organic layer of 3 old-growth black spruce (Picea mariana) forests in the high-boreal forests of Labrador. Stand-replacing wildfires consumed the organic layer and killed the previous stands, producing snags, which subsequently fell and became buried by moss, resulting in large amounts of woody debris (WD) buried deep in the current organic layer. The experimental burial of 45 standardized sample logs at various depths in the organic layer showed that burial significantly decreased WD sapwood and heart temperatures, increased WD moisture content, and tended to decrease WD respiration rates (EGM-4, PP Systems). Buried wood samples collected near the bottom of the organic layer of the 3 sites were up to 450 years old (14C measurements), and had been dead for more than 200 years. The decreased respiration rates of buried sample logs and the presence of old yet well-preserved buried wood in forests where most aboveground WD decays or becomes fragmented within ~70 years of tree death indicates drastically reduced decomposition rates following WD burial by moss. Bryophytes are therefore critical in initiating the formation and accumulation of a large and long-lived buried wood carbon pool, potentially relevant to the carbon cycle of many coniferous forest ecosystems in and outside of the boreal biome.

Molecular diversity of saproxylic fungi and wood decay along a forest disturbance gradient

¹ Hedi Kebli, UQAT

² Pascal Drouin, UQAT

³ Suzanne Brais, UQAT

⁴ Gavin Kernaghan, Mount Saint-Vincent University

Saproxylic pioneer fungi play a key role during wood decomposition process by structuring saproxylics communities. This research aims to understand how communities of pionneer fungi exploiting woody debris organize themselves according to deadwood dynamics as modulated by disturbance type and stand composition. This experiment takes place in stands originating from three different fire episodes along a well-documented post-fire succession. In October 2005, we deposited a total of 480 wood blocks, 240 of balsam fir (Abies balsamea) and 240 of trembling aspen (Populus tremuloides), on the forest floor in three replicates of eight treatments (natural stands, partial cut [six different treatments], and control burned). Blocks were then harvested every six months until January 2008. Using a culture-independent molecular fingerprinting approach, we assessed wood decomposition in relation to pioneer saproxylic fungal diversity and disturbance intensity. Our results underline the differences between trembling aspen and balsam fir wood with respect to factors affecting the diversity and activity of early colonizing fungi in both managed and unmanaged stands. Aspen decomposition proceeded with more efficiency than that of balsam fir as indicated by the strong relationships between time, C:N ratio, wood density, lignin/(lignin + cellulose) ratio and respiration observed for trembling aspen only. Diversity and species richness decreased over time for balsam fir. Although respiration increased with time for both wood species, the increase may result from different processes, increased competition or decomposition, depending on wood species.

Wood Decay Rates Reconsidered: Contrasting Density and Volume Depletion

¹ Amy Milo, US Forest Service Northern Research Station

² Shawn Fraver, US Forest Service Northern Research Station

The abundance, structure, and function of down woody debris (DWD) change continuously as a consequence of tree mortality (DWD additions) and wood decay (losses). In order to model DWD biomass depletions through time, prior studies of decay rates have focused on reductions in wood density. However, this focus overlooks volume reduction of the log itself, a critical metric for modeling structural heterogeneity and habitat diversity through time. Using a number of long-term US Forest Service studies in northern Minnesota, logs of known size, mortality date and cause of death were re-located and sampled to construct a chronosequence (1941 - 2010) of wood densities and log volumes for aspen (Populus tremuloides) and red pine (Pinus resinosa). Log diameters were measured parallel and perpendicular to the forest floor at breast height to calculate change in volume, and cross-sectional samples were returned to the laboratory to determine density. Field measurements show little volume reduction for the first 10 – 20 years after tree death. This plateau is followed by progressive collapse over subsequent decades. These volume-reduction results suggest decay patterns markedly different from existing models used to describe DWD density reduction, a conclusion that will be confirmed by analyzing density values from these same logs. Preliminary data suggest that modeling DWD depletion based on density reduction curves alone is likely to underestimate deadwood abundance, leading to inaccurate representations of fuel loads, carbon storage, and habitat availability.

Time-since-death, decay classes and decay progression in beech and silver fir forests in the central Apennines (Italy)

¹ Fabio Lombardi, University of Molise

² Paolo Cherubini, Science Department

³ Bruno Lasserre, WSL Swiss Federal Research Institute

⁴ Roberto Tognetti, Dendro Sciences

⁵ Marco Marchetti, University of Molise

We investigated the relationship between time-since-death and morphological characteristics of Abies alba Mill. and Fagus sylvatica L. stumps in two forest stands in the central Apennines (Italy). At each site, living trees were selected and increment cores collected to build master ring-width chronologies. For both sites, cross-sections were collected from stumps. Samples were assigned to visually discernible decay classes, and their death date dendrochronologically determined. Moreover, in order to assess changes in chemical variables, cellulose, lignin, C and N content and C:N ratio were analysed during decay processes in relation to the year since death of trees and decay classes assigned in the field. Analysis of the time-since-death of the stumps suggests that the two species have similar decay rates, although A. alba past faster from class 2 to class 3. However, this study revealed a continuum of decay classes, and showed a high variability in the transition rate from one class to another. Results show how C:N ratio decreased over decades due to an increase of N. On the contrary, the C concentration in stumps remained substantially constant throughout the years. Again, lignin content remained stable while cellulose content decreased. This information helps to improve our understanding of terrestrial nutrient cycles in a Mediterranean-type mountain environment and to clarify the role of forest ecosystems, and particularly of deadwood, in carbon sequestration.

Ecological characteristics of mushroom mite assemblage in temperate deciduous forests

¹ Kimiko Okabe, Forestry and Forest Products Research Institute

² Motohiro Hasegawa, Forestry and Forest Products Research Institute

³ Tsutomu Hattori, Forestry and Forest Products Research Institute

⁴ Hiroshi Tanaka, Kansai Research Center

⁵ Shun' ichi Makino, Forestry and Forest Products Research Institute

Wild mushrooms have important functions such as decomposing dead wood and providing habitat and nutrition for invertebrates. By considering mushrooms as invertebrate habitats, we can address ecological questions such as: 1) effects of habitat diversity (mushroom species richness) for inhabitants (invertebrates), 2) importance of connectivity of habitats in conservation of biodiversity (mushrooms are fragmented resources for invertebrates), and 3) a surrogate indicator of forest biodiversity. We collected mites from wild mushrooms to address these questions. Mushroom species richness was significantly correlated with mite diversity in different seasons in an old growth forest (GLM, p = 0.0198). Both mushroom and mite species numbers increased with forest stand age probably because the amount of resources for mushrooms including dead branches and larger dead wood increased. Some mites were collected only from mushroom fruiting bodies but not from the soil or litter around the mushrooms. Mites tended to inhabit fruiting bodies lasting for a long while (e.g., mushroom species except for Agaricales and Phallales mushrooms), generally growing on dead wood and use insects living in mushrooms and/or on dead wood for their dispersal. Therefore, biomass of dead wood could be a surrogate indicator of diversity of both decomposers and organisms associated with the decomposers.

National woody debris decay model for New Zealand.

¹ Loretta Garrett, Scion

² Mark Kimberley, Scion

³ Oliver Graeme, Scion

⁴ Stephen Pearce, Scion

⁵ Peter Beets, Scion

⁶ Paul Thomas, Scion

Woody debris carbon pools make an important contribution to carbon stocks and changes in planted forests in New Zealand. The amount of woody debris (stem, branch and coarse root) in planted forests is dynamic and arises from thinning and harvesting activities. In order to accurately report on the woody debris pools, an improved understanding of the factors that influence the rate of decay of these dynamic carbon pools is required. Pinus radiata comprises 90% of the plantation forests in New Zealand. Decay rate estimates for stems using a chronosequence method and coarse roots using a time series method from P. radiata plantation forest sites over New Zealand were used to generate a national decay model. The model tested for the effect of mean annual temperature, mean annual rainfall, and diameter on the mean decay constant. Branch decay was compared to stem decay. Small to medium sized stems and branches, typical of the debris arising from thinning and harvesting operations, decayed at approximately the same rate. A larger range of stem diameters from young to mature trees showed a diameter effect on decay rate. Coarse root decay was similar or faster than stem decay. Exponential models incorporating mean annual temperature for P. radiata stems plus an initial lag time for coarse roots, provides the best estimate of woody debris decay in New Zealand. Accurately predicting woody debris carbon stocks and changes will improve full accounting of carbon pools in New Zealand’s planted forests.

Decomposition of above and belowground deadwood in managed Sitka spruce forests in Ireland

¹ Samuel Olajuyigbe, University College Dublin

² Maarten Nieuwenhuis, University College Dublin

³ Brian Tobin, University College Dublin

⁴ Paul Gardiner, University College Dublin

In Ireland, Sitka spruce (Picea sitchensis (Bong.) Carr.) accounts for 52.3% of the forest estate. The decomposition and residence time of above and belowground deadwood in managed P. sitchensis forests has management implications for carbon storage, soil strength, belowground habitat, biodiversity and nutrient dynamics. This study determined the decay class density (DCd), decay rates (k), carbon fraction, carbon-nitrogen (C-N) ratio and residence time (95% decomposition) of logs, stumps and roots created from thinning. The roots were excavated and categorized into small (2-10mm), medium (10-50mm) and large (>50mm) diameter classes. The deadwood was classified into DCs, bulk density determined by volume displacement, and C-N analysis was performed on representative samples. Density and deadwood-age (ranging from fresh-17 years) were used to create single-exponential decay curves for logs, stumps and roots. The residence time was estimated using the density decay constant of the deadwood. There were significant differences (p>0.05) in the DCd and C-N ratio of all samples, but no difference for carbon fraction (ranging from 46-48%). The DCd and C-N ratio declined as decomposition progressed. The k was highest for logs (0.0601/yr) and lowest for small roots (0.0303/yr). The residence time was estimated at 50, 63, 99, 67 and 93 years for logs, stumps, and roots (small, medium and large), respectively. The 10-year IPCC-default decay period would appear to be an overestimation and could be increased substantially.

The hidden and unknown biodiversity of dead wood: Saproxylic Collembola in forests of Northern hemisphere

¹ Adrian Smolis, Institute of Zoology University of Wrocław

Thousands of arthropod species in forests use different forms of coarse woody debris. Many of them are ‘saproxylic’ forms that depend, during some parts of their life, on decaying wood, or presence of other saproxylic organisms. Saproxylic species are one of the important components of natural forests, play important roles in nutrient recycling and initial stages of decomposition. In spite of these facts many groups of dead wood-dependent invertebrates, especially microarthropods, have been little studied. Among them springtails are one of the most diverse, widespread and abundant. Recent investigations suggest that soil and litter springtails gain in importance in decomposition processes. Unfortunately, the knowledge of springtails associated with CWD is very scattered. Saproxylic springtails were investigated in North America (Oregon, H.J.AndrewsExperimentalForest) and Europe (Poland, Carpathians), in fragments of ancient old-growth forests with high amount and diversity of CWD. This study allowed to investigate species richness of Collembola associated with CWD, and asses number of saproxylic springtails depending on presence of decaying wood and number of species facultatively utilizing logs. Saproxylic Collembola restricted to CWD are characterized by distinct features: absence of body pigment, strong reduction of eyes and jumping organ, relatively short antennae and legs, often dorso-ventrally flattened body shape. Some interesting taxa and the most important features of the springtail wood-dependent community: the proportion of number of species belonging to different families, life-forms and feeding habits, are presented. Additionally, description of new saproxylic springtail species is provided.

Nutrient (N, C, S) concentrations and wood decomposition in windthrow areas in Estonia.

¹ Kajar Köster, Estonian University of Life Sciences

² Kalev Jõgiste, Institute of Forestry and Rural Engineering / University of Helsinki

Total concentration of 3 chemical elements (N, C, S) and factors affecting early wood decomposition (wood density changes) were measured in standing, leaning and downed dead wood in two windthrow areas in eastern Estonia, which experienced storms on summers of 2001 and 2002. Samples for chemical analyzes and wood density measurements were taken from Norway spruce (Picea abies (L.) Karst.) and birch (Petula pendula Roth.) in 2004 and 2008. The wood samples were taken from trees located in totally damaged (TD), partly damaged (PD) and control areas with no damage (ND). Total nitrogen, carbon and sulphur content of oven- dried samples were determined by dry combustion method. Sample volume was determined by water displacement technique. Wood densities after initial period of decomposition were significantly different, depending on tree species, log or snag position, and damage severity. Snags/logs from TD area had a lower density than those from PD area. Annual decomposition rates ranged from 0.78% to 5.57% for spruce and 2.19% to 7.42% for birch. In the case of birch, average nitrogen stores increased in TD areas by 39% and in PD areas by 26%. Average nitrogen stores for spruce decreased in TD areas by 22% and in PD areas by 12%. In birch the average carbon concentration increased 5-6 years after disturbance, while for spruce the concentration stayed stable. Sulphur concentrations increased slightly in both tree species.

Deadwood as a surrogate for forest biodiversity: Meta-analysis of correlations between deadwood volume and species richness of saproxylic organisms.

¹ Aurore Lassauce, ADEME - Cemagref

² Yoan Paillet, Cemagref

³ Hervé Jactel, INRA

⁴ Christophe Bouget, Cemagref

Deadwood is an important component of forest ecosystems on which many forest dwelling species depend. Deadwood volume is therefore widely used as an indicator of biodiversity, notably throughout Europe. However, using deadwood as an indicator has mostly been based on boreal references, and published references for temperate forests are scarce. As a result, the magnitude of the relationship between deadwood volume and species richness remains unclear for saproxylic species. We used meta-analysis to study the correlation between deadwood volume and the species richness of saproxylic beetles and fungi relative to several covariables: biome, type of deadwood (log, snag, and stump) and decay class (fresh versus decayed). We showed that the correlation between deadwood volume and species richness of saproxylic organisms was significant but moderate (r=0.31), and that it varied slightly between logs and snags (stumps were an exception) and decay stages. However, we found a strong biome effect: deadwood volume and species richness were more correlated in boreal forests than in temperate forests. This could be attributed both to differences in the history of forest management between biomes and to varying landscape patterns. Finally, we conclude that total deadwood volume is probably not a sufficient indicator of biodiversity, and that landscape variables and other variables such as those tested here should be integrated in deadwood monitoring. In addition, further research is needed in forests to better assess the relationship between deadwood and biodiversity in order to build indicators adapted to different biome contexts.

Consideration of coarse woody debris as protection against rockfall in mountainous forest.

¹ Christophe Bigot, Cemagref

² Frédéric Berger, Cemagref

³ Jean-Jacques Brun, Cemagref

⁴ Laurent Astrade, Edytem

Each year in mountains, natural hazards generate extensive damage and sometimes even casualties. During rockfalls, forests can play an important role of passive protection by increasing the energy dissipation of falling rocks. Up to now, many studies have shown the efficiency of standing forests in protection against rockfalls, but these studies are have only considering living trees. In Austria and Switzerland, managers have been using stumps, logs and other timber products to create natural dams against rockfalls over the last twenty years. Today, French foresters have adopted these techniques, but there is still a lack of knowledge on the efficiency and the lifetime of such protective structures. The main objectives of this research are to quantify the mechanical resistance loss according to wood decay kinematics. The studied materials include logs, stumps and roots. Preliminary works have been done in order to select experimental plots in the Alpine Area. The species studied are: silver fir, norway spruce, european beech and pinus nigra. Wood decay rates are quantified by using a chronosequence approach. Different methods are used to quantify wood density loss. A specific protocol, based on both non-destructive and destructive tests, has been built for analysing the loss of mechanical resistance of these woody elements. The final objective is to integrate, in 3D rockfall trajectory simulation models, the actions of these biological engineering protective works taking into account the evolution in their efficiency within their lifetime.

Effects of intensified forestry on the landscape-scale extinction risk of dead-wood dependent species

¹ Jean-Michel Roberge, Swedish University of Agricultural Sciences, Dept. of Wildlife, Fish, and Environmental Studies

² Thomas Ranius, Swedish University of Agricultural Sciences, Dept. of Ecology

In the future, a significant proportion of northern forests may become intensively managed through the planting of monospecific stands of native or introduced trees, and the use of multiple silvicultural treatments such as forest fertilization. Such an intensification of management in selected parts of the landscape is suggested by different zoning models, for example the TRIAD approach, which is under evaluation in some regions of North America. In this study, we predicted landscape-scale extinction risks of five hypothetical model insect species dependent on fresh dead wood from Norway spruce (Picea abies), by simulating colonizations and local extinctions in forest stands. Intensified forestry applied to 50 % of the spruce stands led to strongly increased extinction risks of all species during the following 150 years. For one species – the sun-exposure specialist – there were strong effects already after 50 years. The negative effects of intensive plantation forestry could be compensated for by taking greater biodiversity conservation measures in other managed forests or by setting aside more forests. This is consistent with the TRIAD model, which is according to our analyses an effective way to decrease extinction risks, especially for the short-dispersing species and the species associated with closed forest. A zoning of forest land into intensive forestry, conventional forestry, and set asides seems to be better at combining increased timber production and maintenance of biodiversity in comparison to landscapes where all production forests are managed in the same way.

Bryophyte diversity associated with black spruce woody debris in boreal forests

¹ Julie Arseneault, UQAT - Chaire AFD & CEF

² Nicole Fenton, UQAT & Chaire AFD

³ Yves Bergeron, UQAT - UQAM - Chaire AFD & CEF

Bryophytes account for a large proportion of plant diversity in the boreal forest. Coarse woody debris (CWD) represents a substrate propitious for the establishment of rich bryophyte communities. However, CWD amounts and characteristics vary in time as it decomposes. Harvesting applies a negative pressure on woody debris reducing inflow and relocating and crushing existing woody debris. This project aims to measure the effects of two harvesting techniques on the spatial repartition of black spruce (Picea mariana, (Mill.)) coarse woody debris, on CWD characteristics and on the associated bryophyte diversity. Our main hypotheses are: (1) total richness of bryophytes species will be higher in sites with all decomposition classes represented, and (2) canopy openness reduces woody debris quality, leading to loss of epixilic species and favouring the establishment and growth of some Sphagnum species. The three study sites are located in homogenous black spruce stands prone to paludification in western Quebec. Within each site, a careful logging (CL), a partial cut (PC) and an old growth forest (OG) stand were sampled. Woody debris quality was recorded for 225 woody debris pieces. On each piece of debris, microplots were sampled for bryophytes and samples were taken from 45 of these debris. Results suggest a tendency towards species loss, a dominance of sphagna and fewer available pieces of woody debris after CL, while PC seems more similar to OG. Environmental factors that differed among treatments influenced CWD characteristics and associated bryophyte diversity.

A deadwoodologist’s digest: an A-to-Z of learnings from a decade of research in Tasmania

¹ Simon Grove, Forestry Tasmania

This presentation outlines findings from a decade of targeted research on dead wood, its dynamics and its biodiversity in the cool temperate eucalypt forests of Tasmania, Australia. These have many parallels with other parts of the world, but also many differences. Rather than attempting a formal synthesis from this web of research, an eclectic yet informative set of findings is presented in sequence, one or more for each letter of the alphabet. Together these provide evidence for dead wood being a fundamental and prominent component of this ecosystem, and provide pointers for how to sustain the ecological values of dead wood in managed forest landscapes.

Home range and stand scale effects of coarse woody debris on boreal small mammals

¹ Dominique Fauteux, UQAT - Chaire AFD & CEF

² Louis Imbeau, UQAT - Chaire AFD & CEF

³ Pierre Drapeau, UQAM - Chaire AFD & CEF

⁴ Marc J. Mazerolle, UQAT - Chaire AFD & CEF

Coarse woody debris (CWD) are actively selected by small mammals to protect themselves against predators, to feed, and for more efficient energy expenditures. We studied the importance of CWD for several small mammal species in the spruce-moss zone of western Quebec boreal forests. Specifically, we compared the effects of CWD on small mammals in clearcuts, partial cuts, and control stands. We analyzed small mammal abundance by using a spatially- and temporally-structured trapping system which allowed us to study the effects of CWD at two spatial scales: home range and stand. Our results showed that most sampled species were affected by well-decayed logs at different spatial scales. At the home range scale, red-backed voles (Myodes gapperi), a species usually associated with mature and undisturbed stands, consistently selected sites with the highest volumes of well-decayed logs across all three treatments. Predictions from our models suggested that patches of partial cuts composed of high volumes of well-decayed logs may maintain similar abundances of red-backed voles as patches in control stands with small volumes of logs. Meadow voles (Microtus pennsylvanicus) selected logs at the stand scale. This last observation suggested that microhabitat selection for this species was mainly driven by density-dependent factors. Our study indicated that CWD legacies should be considered as much as live tree retention when managing forests for biodiversity. We recommend maintaining patches of standing trees and snags that will contribute to CWD dynamics over time in clearcuts and partial cuts.

Extinction debt among wood fungi in small fragmented boreal forest stands

¹ Bengt Gunnar Jonsson, Fish and Environmental Studies

² Håkan Berglund, Mid Sweden University

Fennoscandian forests have been subject to industrial forestry for more than a century and remaining forests of high natural value are increasingly fragmented and isolated. Population dynamics are slow for some species groups, and during the rapid transformation of the forest landscape the occurrence of species may not be in synchrony with the current landscape and habitat conditions. This poses challenges to evaluating the role of small set asides where a significant extinction debt may be present. Although the theoretical foundation for an extinction debt is well established the amount of empirical data confirming its existence is limited. Based on extensive inventories of naturally fragmented forest patches in comparison with a set of more or less recently isolated fragments in the managed landscape, we evaluated the presence and magnitude of the extinction debt of wood living fungi. The results show clear evidence of a continued loss of species and decreasing population size during the first decades after isolation. Further, the results support the threat status of red-listed species as these dominated among species showing a temporal decline after isolation. Our results provide much needed empirical support for the presence of an extinction debt in small set-asides and emphasize the need to consider long term population trends in designing efficient conservation strategies.

Biodiversity, structure and process: changes in saproxylic beetles, deadwood and decomposition rates following forest harvest.

¹ Jenna Jacobs, UQAM - Chaire AFD & CEF

² Timothy T. Work, UQAM - Chaire AFD & CEF

The effects of forest harvest on biodiversity, forest structure and ecosystem processes are often considered independently in studies of forested ecosystems. However these three components of forested ecosystems do not work independently and especially in deadwood habitats there can be a high degree of interaction. Here, we used a network of partial cutting sites in the black spruce dominated region of north-western Quebec and monitored the response of saproxylic beetles and polypore fungi, the changes in forest structure and woody decomposition rates. We found that any amount of cutting greatly altered the saproxylic beetle assemblages and changed relative dominance of polypore fungi. Furthermore, cutting tended to increase the total amount of deadwood in the short term and change relative representation of different types of fungi. Decomposition rates also progressively increased with harvesting intensity, where total cuts had 50% higher decomposition rates than uncut stands using a stand negative exponential model of wood decay. We concluded that changes in environment caused by forest harvesting increased fungal growth rates and therefore decomposition rates. Increases in fungi also had the effect of increasing fungivore diversity and increased the total number of predators found in the cut stands. The implications of this research is that deadwood habitats will disappear faster in the cut stands threatening the large component of biodiversity which depend on deadwood habitats.

Dead wood diversity promotes saproxylic biodiversity

¹ Joakim Hjältén, Department of Wildlife, Fish and Environmental Studies

Saproxylic (wood living) species are threatened due to intensified forest management. Increasing the amount of dead wood in the managed forest landscape is therefore of high priority. However, in many cases only one type of dead wood is produced, e.g. height stumps and it is unlikely that this will be a suitable substrate for all saproxylic species of concern. To determine the relative importance of dead wood diversity we conducted a large scale field experiment at 10 locations, each consisting of three forest types, old growth forest reserve, mature managed forest and a clear-cut, in Northern Sweden. At each location we placed a total of 10 standardized experimental substrates (Birch and Spruce substrates including, high stumps, logs, inoculated with different types of wood fungi, burned or shaded). Emergence traps were used to collect insect emerging from the different dead wood substrates. During 2003-2004 we collected and identified ca 80 000 saproxylic beetle individual belonging to more than 380 species. We found clear evidence that one substrate type is insufficient to maintain saproxylic biodiversity. Many species were more or less confined to one substrate type. However, many of these early successional saproxylic species are surprisingly generalistic with regard to substrate choice. Still our results strongly suggest that it is necessary to provide diversity of substrate types in the managed forest landscape to maintain saproxylic diversity.