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Expanding markets for renewable energy feedstocks have increased demand for woody biomass. Concerns associated with forest biomass harvesting include increased erosion, the applicability of conventional forestry Best Management Practices (BMPs) for protecting water quality, and reduced woody debris retention for soil nutrients and cover. We regionally compared the data and results from three prior independent studies that estimated erosion, BMP implementation, and residual woody debris following biomass and conventional forest harvests in the Mountains, Piedmont, and Coastal Plain of Virginia. Estimated erosion was higher in the Mountains due to steep slopes and operational challenges. Mountain skid trails were particularly concerning, comprising only 8.47% of the total area but from 37.9 to 81.1% of the total site-wide estimated erosion. BMP implementation varied by region and harvest type, with biomass sites having better implementation than conventional sites, and conventional Mountain sites having lower implementation than other regions. Sufficient woody debris remained for BMPs on both harvest types in all regions, with conventional Mountain sites retaining twice that of Coastal Plain sites. BMPs reduced the estimated erosion on both site types suggesting increased implementation could reduce potential erosion in problematic areas. Therefore, proper BMP implementation should be ensured, particularly in Mountainous terrain, regardless of harvest type.

Expanding markets for renewable energy feedstocks have increased demand for woody biomass. Concerns associated with forest biomass harvesting include increased erosion, the applicability of conventional forestry Best Management Practices (BMPs) for protecting water quality, and reduced woody debris retention for soil nutrients and cover. We regionally compared the data and results from three prior independent studies that estimated erosion, BMP implementation, and residual woody debris following biomass and conventional forest harvests in the Mountains, Piedmont, and Coastal Plain of Virginia. Estimated erosion was higher in the Mountains due to steep slopes and operational challenges. Mountain skid trails were particularly concerning, comprising only 8.47% of the total area but from 37.9 to 81.1% of the total site-wide estimated erosion. BMP implementation varied by region and harvest type, with biomass sites having better implementation than conventional sites, and conventional Mountain sites having lower implementation than other regions. Sufficient woody debris remained for BMPs on both harvest types in all regions, with conventional Mountain sites retaining twice that of Coastal Plain sites. BMPs reduced the estimated erosion on both site types suggesting increased implementation could reduce potential erosion in problematic areas. Therefore, proper BMP implementation should be ensured, particularly in Mountainous terrain, regardless of harvest type. [ABSTRACT FROM AUTHOR]

IntroductionIncreasing temperatures associated with climate change can lead to more challenging conditions for tree seedlings, including greater soil surface temperatures and reduced growing season soil moisture. Downed woody debris (DWD) may provide microsite effects, such as shade, that moderate these conditions for seedlings. However, few studies have conducted fine-scale assessments of the strength of the microsite as a function of distance from DWD or how the microsite effect differs between species or across topographic gradients.MethodsIn this study, conducted in the Palouse region of eastern Washington State, we placed three large pieces of DWD (5 m length × 40–50 cm small-end diameter, oriented east–west) on each of three topographic facets (north-facing, flat ridge-top, and south-facing), and planted transects of seedlings of a xerophytic conifer (ponderosa pine, Pinus ponderosa) and a mesophytic conifer (Douglas-fir, Pseudotsuga menziesii) on both sides of the DWD at fixed distances (0, 0.25, 0.5, and 1.5 m). The 1.5 m distance was assumed to serve as a control, with no measurable influence from DWD. Seedling responses (stress rating, survival, basal diameter and height growth, and dark-adapted chlorophyll fluorescence) over two growing seasons were used to interpret the influence of DWD on seedling health and survival, especially during stressful episodes of extreme heat, such as occurred during July 2021, the first growing season of the experiment. Soil surface temperature and soil volumetric water content (10 cm depth) were measured at all seedling locations to understand biophysical contributors to seedling response.ResultsWe found that seedlings of both conifers displayed lower stress ratings, higher survival, and greater height growth close to the north side of DWD, with this effect especially pronounced on the flat ridge-top and the south-facing slope. Soil surface temperature decreased greatly in the “shade zone” at 0.0 m and 0.25 m distances on the north side of DWD, and soil volumetric water content declined more quickly outside of the shaded microsite.DiscussionThese findings suggest that creating or retaining DWD on stressful sites may prove an important climate adaptive management strategy in ecosystem restoration or forest management, especially if extreme heat events continue to increase in frequency.

Downed woody debris (DWD) can alter the chemical and biological properties of forest soils, and this process is affected by the degree of DWD decay. Our aim was to assess the effects of the entire decay process of DWD on the associated soil microbial communities. Here, we examined the differences in soil microbial community size and composition among five decay stages (DC Ⅰ–Ⅴ) of Masson pine (Pinus massoniana Lamb.) at two soil depths in a climate transitional forest and then linked these differences to soil chemical properties. The decay of DWD increased soil total PLFAs, and the complexity of soil microbial networks was highest in stage Ⅱ and then decreased with the decay stage. The relative abundance of fungi increased with the decay stage, while the relative abundance of gram-positive bacteria decreased with the decay stage. The microbial community composition at a soil depth of 0–10 cm was mainly driven by soil pH and organic C (SOC), and at a depth of 10–20 cm, soil pH was the primary determinant of microbial community composition. Our findings suggest that DWD decomposition reduces microbial physiological stress, promotes fungal growth, and stimulates microbial biomass, highlighting the positive impact of DWD on forest soils. Future research is needed to elucidate the universal effects of DWD decomposition on soil properties, especially focusing on the response of soil microbial processes to the decomposition time of DWD. [ABSTRACT FROM AUTHOR]

Abstract In the context of global change, a better understanding of the dynamics of wood degradation, and how they relate to tree attributes and climatic conditions, is necessary to improve broad‐scale assessments of the contributions of deadwood to various ecological processes, and ultimately, for the development of adaptive post‐disturbance management strategies. The objective of this meta‐analysis was to review the effects of tree attributes and local climatic conditions on the time since death of coarse woody debris ranging in decomposition states. Results from our meta‐analysis showed that projected warming will likely accelerate wood decomposition and significantly decrease the residence time in decay stages. By promoting such a decrease in residence time, further climate warming is very likely to alter the dynamics of deadwood, which in turn may affect saproxylic biodiversity by decreasing the temporal availability of specific habitats. Moreover, while coarse woody debris has been recognized as a key resource for bioenergy at the global scale, the acceleration of decay‐stages transition dynamics indicates that the temporal window during which dead trees are available as feedstock for value‐added products will shrink. Consequently, future planning and implementation of salvage harvesting will need to occur within a short period following disturbance, especially in warmer regions dominated by hardwood species. Another important contribution of this work was the development of a harmonized classification system that relies on the correspondence between the visual criteria used to characterize deadwood decomposition stages in locally developed systems the literature. This system could be used in future investigations to facilitate direct comparisons between studies. Our literature survey also highlights that most of the information on wood decay dynamics comes from temperate and boreal forests, whereas data from subtropical, equatorial and subarctic forests are scarce. Such data are urgently needed to allow broader‐scale conclusions on global wood degradation dynamics.

Water quality best management practices (BMPs) developed for conventional forest harvests may be adequate for biomass harvests, yet quantitative data is lacking. This study compared estimated erosion, operational feature areas, BMP implementation rates, ground cover characteristics, and downed woody debris quantities following biomass and conventional harvests in the mountains of Virginia. Haul roads on biomass harvests had significantly higher estimated erosion rates (P  = 0.064) and masses (P  = 0.045) than conventional harvests, but conventional harvests had higher erosion contributions from skid trails (P  = 0.089) and averaged more estimated erosion mass overall, despite being significantly smaller in size (P  = 0.054). There was significantly less area in heavy slash (P  = 0.076) and lower estimated mass of residual downed woody debris (P  = 0.001) on biomass sites than conventional sites (10.98 and 27.95 tons/ac, respectively). Site-wide BMP implementation scores (P  = 0.041), streamside management zones (SMZs) (P  = 0.024), and skidding (P  = 0.063) were significantly higher on biomass sites than conventional sites. BMP implementation scores were significant predictors of estimated erosion rates (P  < 0.001, R 2  = 59%), indicating that adequate levels of existing water quality BMPs are effective for erosion control on both conventional and biomass harvests. [ABSTRACT FROM AUTHOR]

Wind disturbance in northern hardwood forests of the US North Central Great Lakes region creates heterogeneously distributed structural attributes such as downed woody debris (DWD) and canopy openings across temporal and spatial scales. The decomposition of DWD contributes to greenhouse gas (GHG) fluxes, provides habitat, and potentially influences soil biogeochemistry. We assessed the effects of DWD addition on soil GHG fluxes in the decade after experimental manipulation of downed woody amounts and canopy openings in a maturing second-growth deciduous forest to (1) determine the spatial relationship between DWD proximity and soil GHG fluxes (CO2, CH4, N2O); (2) evaluate the relationship of decay class, canopy condition and environmental variables to wood decomposition and soil fluxes; and (3) use the fine scale surface patterns to estimate carbon emissions from the ground layer stratum. Our results revealed the shifting influence of individual pieces of DWD on soil microbial activity with advancing wood decay and depending on canopy condition. Modeled daily soil CO2 fluxes increased near moderately and highly decayed DWD in open canopy compared to control soils but decreased near highly decayed wood in closed canopy. Despite high variability and low CH4 (mean: − 0.02 ± 0.01 mg m−2 s−1) and N2O (mean: − 0.0007 ± 0.0008 mg m−2 s−1) soil fluxes, higher uptake in closed canopy paralleled the patterns of CO2 efflux. Our findings indicated that northern hardwood forests have the potential to be important CO2 and trace gas sinks, especially under intact canopy, but that widespread reductions in DWD in secondary forests of the region likely altered potential GHG soil uptake. [ABSTRACT FROM AUTHOR]

Coarse woody debris (CWD) is a dynamic source of nutrients in managed forests of eastern North America. The temporal patterns of nutrient export from CWD are challenging to study, and efficient methods are lacking. We made empirical measurements of CWD density, volume, and nutrient concentrations in 5 stages of decay, and paired them with a decay class transition model to project the long-term nutrient dynamics of CWD in a managed northern hardwood forest. The model was used to describe stand-level changes in CWD nutrient pools over 40 years following a selection harvest, and to compare CWD nutrient pools in managed and unmanaged stands. The C content of CWD decreased throughout decay, and mirrored density losses. N, P, and Ca content increased throughout decay, Mg content remained relatively constant, and K was rapidly lost. At the stand level, despite a rapid loss of mass and density, the model projected an initial gain in total N, P and Ca stored in CWD during the first 4–8 years after harvest, whereas net C, Mg, and K began to decrease immediately. The average volume, mass, C and K stocks of CWD in managed stands were approximately 10% lower than unmanaged stands, and N, P, Ca, and Mg were up to 16% lower. This is the first study to use a decay class transition model to study the dynamics of nutrients other than C, and the model serves as a template upon which other models of CWD decay can be built. [ABSTRACT FROM AUTHOR]

Abstract Coarse woody debris (CWD) is an important contributor to forest biodiversity because it provides essential habitat for saproxylic (dead wood‐dependent) species. However, CWD is frequently overlooked in forest management and restoration decisions around the world. We have therefore developed an index of CWD habitat quality that integrates four important characteristics of saproxylic habitat. We apply this index to wet eucalypt forests in Tasmania, Australia. The relationships between the CWD index and standing forest structural and floristic maturity metrics were weak (R2

In this study we analysed a dataset of 8661 logs of silver fir ( Abies alba Mill.) and Norway spruce ( Picea abies L., Karst) in mixed fir-spruce-beech stands in primeval and natural forests in four sites separated into the two macroclimatic categories according to mean annual temperature (“cold” and “warmer”) and according to mean annual precipitation (“mesic” and “humid”). We used “Bayesian Survival Trajectory Analysis” on a more than 40-year long time series (1972–2015), focusing on differences in the residence time of deadwood in different macroclimatic categories and two DBH classes. We also evaluated two qualitative characteristics of the downed logs: mortality mode and log position during decomposition. We calculated residence time and the time needed to reach the advanced decay stage. Our analyses confirmed the influence temperature and precipitation on modelled residence time. The residence time for silver fir logs in the DBH class 55+ cm in the “cold” site was 106 years, while in the “warmer” sites was 78 years. The residence time in the “mesic” site was 57 years, while in the “humid” sites was 90 years. It took 81 years for Norway spruce logs in the DBH class 55+ cm to completely decompose in the “cold” site. Suspended logs 11 took years longer to decay than those in contact with the ground. The modelled residence time of logs on wet sites was the same as that of logs at sites unaffected by water. These results can be utilised in biodiversity oriented forest management, as well as in modelling future amounts of deadwood. In order to maintain the continuous presence of silver fir and Norway spruce deadwood for those organisms that depend on it, it is necessary to supply deadwood at least once every 25–40 years (depending on climatic category and DBH class). During this time, approximately 50% of logs become completely decomposed and 50% remain in the last decay stage. [ABSTRACT FROM AUTHOR]

ABSTRACT Harvest of low value trees and logging residues for bioenergy reduces downed wood post-harvest with potential indirect negative effects on ground-dwelling wildlife such as rodents. We assessed the influence of woody biomass harvests on rodent abundances using an operational-scale, randomized complete block experimental design study in North Carolina (4 blocks) and Georgia, USA (4 blocks). Each block contained 6 treatments randomly applied to a clearcut harvest, that varied by volume of woody biomass retained, and that represented existing woody biomass harvest recommendations. We livetrapped rodents in 2011-2013, calculated the minimum number known alive for each captured species, and used the value as an index of abundance. We compared abundance of the 3 most commonly captured species (deer mice [ Peromyscus spp.], house mouse [ Mus musculus], and hispid cotton rat [ Sigmodon hispidus]) among treatments with generalized linear mixed effects models. We assessed relationships among species' abundance and measurements of downed woody debris and vegetation in each treatment unit using linear regression. Although abundance varied among treatments in some cases, we did not detect consistent relationships between woody biomass retention treatments and abundance. Volume of downed woody debris in the treatment unit negatively influenced house mice but had varying influences on deer mice across years. Downed woody debris groundcover negatively affected deer mice in North Carolina in 2012. Litter groundcover negatively influenced deer mice and hispid cotton rats, whereas grass groundcover positively influenced the hispid cotton rat. The lack of consistent relationships between rodent abundance and volume of retained woody debris suggests that the rodent species captured in this study were not affected by current efficiencies of operational woody biomass harvests in southeastern United States loblolly pine ( Pinus taeda) plantations. However, focal species were habitat generalists and less common species may have greater sensitivity to biomass harvests. © 2017 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Recent evidence suggests that invasive exotic plants can provide novel habitats that alter animal behavior. However, it remains unclear whether classic animal-habitat associations that influence the spatial distribution of plant-animal interactions, such as small mammal use of downed woody debris, persist in invaded habitats. We removed an invasive exotic shrub (buckthorn, Rhamnus cathartica) from 7 of 15 plots in Wisconsin. In each plot, we deployed 200 tagged Quercus rubra seeds in November 2014. After five months, tags were recovered to track spatial patterns of small mammal seed predation. Most recovered tags were associated with consumed seeds (95%); live-trapping, ancillary camera-trapping, and previous behavioral studies suggest that white-footed mice ( Peromyscus leucopus) were responsible for most seed predation. In habitats without R. cathartica, most seed predation occurred near woody debris. In habitats with R. cathartica, small mammals rarely consumed seeds near woody debris, and seed predation occurred farther from the plot center and was less spatially clustered. Our results illustrate that invasive exotic shrubs can disrupt an otherwise common animal-habitat relationship. Failing to account for changes in habitat use may diminish our ability to predict animal distributions and outcomes of species interactions in novel habitats created by invasive exotic plants. [ABSTRACT FROM AUTHOR]

Forests are a major supplier of renewable energy; however, gleaning logging residues for use as woody biomass feedstock could negatively alter habitat for species dependent on downed wood. Biomass Harvesting Guidelines ( BHGs) recommend retaining a portion of woody biomass on the forest floor following harvest. Despite BHGs being developed to help ensure ecological sustainability, their contribution to biodiversity has not been evaluated experimentally at operational scales. We compared herpetofauanal evenness, diversity, and richness and abundance of Anaxyrus terrestris and Gastrophryne carolinensis among six treatments that varied in volume and spatial arrangement of woody biomass retained after clearcutting loblolly pine ( Pinus taeda) plantations in North Carolina, USA ( n = 4), 2011-2014 and Georgia ( n = 4), USA 2011-2013. Treatments were: (1) biomass harvest with no BHGs, (2) 15% retention with biomass clustered, (3) 15% retention with biomass dispersed, (4) 30% retention with biomass clustered, (5) 30% retention with biomass dispersed, and (6) no biomass harvest. We captured individuals with drift fence arrays and compared evenness, diversity, and richness metrics among treatments with repeated-measure, linear mixed-effects models. We determined predictors of A. terrestris and G. carolinensis abundances using a priori candidate N-mixture models with woody biomass volume, vegetation structure, and groundcover composition as covariates. We had 206 captures of 25 reptile species and 8710 captures of 17 amphibian species during 53 690 trap nights. Herpetofauna diversity, evenness, and richness were similar among treatments. A. terrestris abundance was negatively related to volume of retained woody biomass in treatment units in North Carolina in 2013. G. carolinensis abundance was positively related with volume of retained woody debris in treatment units in Georgia in 2012. Other relationships between A. terrestris and G. carolinensis abundances and habitat metrics were weak or absent. The lack of consistent community or population responses suggests the addition of a woody biomass harvest to a clearcut in pine plantations does not impact herpetofauna use of Coastal Plain loblolly plantations in the southeastern United States. We recommend additional research to examine relationships between woody biomass harvesting and rarer species or amphibians with high desiccation risk, particularly in other regions and harvesting systems. [ABSTRACT FROM AUTHOR]

Our objective was to determine if a retention area-based Biomass Harvesting Guideline (BHG) strategy maintained desired volumes of downed woody debris (DWD) following woody biomass harvests. We implemented six randomly-assigned treatments in four clearcuts in loblolly pine plantations in the Coastal Plain physiographic region of North Carolina during 2010–2011: 1) woody biomass harvest with no BHGs (NOBHG); 2) 15% retention with woody biomass dispersed (15DISP); 3) 15% retention with woody debris clustered (15CLUS); 4) 30% retention with woody biomass dispersed (30DISP); 5) 30% retention with woody biomass clustered (30CLUS); and 6) no woody biomass harvest (i.e., clearcut only; NOBIOHARV). Prior to harvesting, we flagged 15% or 30% of the treatment area to serve as woody biomass retention sources for the four BHG treatments, and all woody biomass from the flagged area were retained and distributed across that entire treatment area. We examined effects of treatments on: 1) fraction estimated volume of pre-harvest standing volume (total and woody biomass) retained as residual DWD; and 2) fraction retained DWD in treatments 2–5 relative to retained DWD in the NOBHGS and NOBIOHARV treatments. Adding a woody biomass harvest reduced volume of residual DWD by 81% in NOBHG compared to NOBIOHARV. Estimates based on the second metric were most similar to target retentions with retention percentages at 18.8% in 15CLUS, 14.1% in 15DISP, 39.0% in 30CLUS, and 38.0% in 30DISP. Treatments resulted in retention of DWD fractions approximate to those prescribed, suggesting BHGs can be implemented successfully in an operational setting. [ABSTRACT FROM AUTHOR]

Aboveground deadwood, consisting of downed woody debris (DWD), snags, and stumps, is an important component of boreal forest ecosystem structure. Accurate deadwood density estimates are essential for evaluating ecosystem biomass and carbon stocks. The objective of this study was to examine the relationships between deadwood density, tree species, and decay status, identified in the field by morphological characteristics. We sampled DWD, snags, and stumps of trembling aspen (Populus tremuloides Michx.), paper birch (Betulapapyrifera Marsh.), jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana [Mill.] B.S.P.), and balsam fir (Abies balsamea [L.] Mill.) in the boreal forest of central Canada. A total of 240 samples (99 DWD, 94 snags, and 47 stumps) were collected. Decay class and tree species explained >80% of the variation in wood density of all deadwood types. Wood density decreased consistently from the lowest to the highest decay class. Tree species identity was also important in determining the relationships between wood density and fieldassigned decay class for snags and stumps, but not for DWD, probably because of the five-class system used for DWD, rather than the three-class system used for snags and stumps. These results indicate that decay class and tree species are adequate predictors of deadwood density. [ABSTRACT FROM AUTHOR]

We investigated how post-fire salvage logging of Ponderosa Pine (Pinus ponderosa) affected populations of cavity-nesting birds and small mammals in southeastern Montana in 2004 and 2005. We examined two salvage and two control plots with three point-count stations and one small mammal trap site randomly distributed across each plot. We used point counts and distance sampling methods to estimate density of cavity-nesting birds on each treatment. We also searched each plot for nests and used program MARK to construct a set of candidate models to investigate variations in nest survival related to treatment, year, and time. We used live traps arranged in webs centered on trapping sites and distance sampling methods to estimate small mammal density. Habitat characteristics were also quantified on each plot. Density of all cavity-nesting birds combined and of Hairy Woodpeckers (Picoides villosus) in particular were higher on the control than the salvage treatment. Density of large trees and abundance of active cavities were higher on the control treatment. Nest cavities on the salvage treatment were most often located in non-logged watersheds. Nest survival estimates were uniformly high, with only marginal variations attributed to treatment and year. Density of Deer Mice (Peromyscus maniculatus) was higher on the salvage than the control treatment, reflecting the amount of downed woody debris created during harvest. [ABSTRACT FROM AUTHOR]

Abstract: Forest management approaches are increasingly being focused on restoring or retaining structurally complex old forest conditions. Evaluations of the long-term impacts of different management regimes on the maintenance and restoration of these conditions are critical for informing and refining current management approaches. To this end, we examined the long-term effects of differing intensities of single-tree selection harvest on stand structural attributes within northern hardwood forests in the Upper Peninsula of Michigan, USA. Stands in this study were classified as old growth at the onset of the experiment and were repeatedly treated and maintained at three residual stocking levels (11.5, 16.1, and 20.7m2 ha−1 in trees greater than 24cm DBH) with three different cutting cycle lengths (5, 10, and 15 years) over a 57-year period. Conditions within an adjacent, unmanaged old-growth system were used as a benchmark for comparing stand structural attributes, including abundance of downed woody debris (DWD), regeneration, and large diameter trees. Stand stocking level was the primary factor affecting the long-term trends in stand structure and composition observed among stands. In particular, stands maintained at a 11.5m2 ha−1 stocking level had significantly lower amounts of DWD, snags, and large overstory trees compared to the 20.7m2 ha−1 stocking level. Similarly, the highest stocking level treatment had the greatest abundance of Betula alleghaniensis relative to the other two stocking level treatments. In addition, long-term trends in diameter distribution forms indicated that the two highest stocking level treatments largely displayed increasing q and negative exponential curve forms over time, whereas the 11.5m2 ha−1 stocking level was primarily characterized by concave distribution forms. Ordination analyses of stand structural attributes indicated that stands managed with the highest residual stocking levels contained stand structural characteristics approximating those found within the unmanaged, old-growth benchmark stand, whereas the lowest stocking level was much less complex. These results suggest that single-tree selection systems that maintain high stand residual basal areas, a portion of which is made up of large diameter, below-grade, defective trees, could serve as a potential means to integrate or retain old-growth forest elements in managed stands. [Copyright &y& Elsevier]

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Coarse woody debris (CWD) volume and diversity are vital attributes of forest ecosystems. However, despite their importance, their long-term dynamics associated with fire- or logging-origin and overstory type have not been examined in boreal forest. We hypothesize that (1) CWD compositional diversity increases with stand development whereas CWD volume follows a U-shaped pattern. Furthermore, we attempted to test if (2) CWD volume and compositional diversity converge for postlogged and postfire stands through stand development, and (3) mixedwoods have more CWD volume and greater compositional diversity than conifer or broadleaf overstory types. We sampled 72 stands ranging in age from 7 to 201 years in fire-origin stands and 7–31 years in managed stands with conifer, mixedwood, and broadleaf overstory types in central boreal Canada. For fire-origin stands, snag volume was 100–260 m3/ha in 7-year-old stands, 5–20 m3/ha in 25-year-old stands, and 25–60 m3/ha in older stands; downed woody debris (DWD) volume decreased from 7 to 72–90 year-old stands, increased in 124- to 139-year-old stands, then either decreased or increased in 201-year-old stands depending on overstory type. CWD diversity increased from 25 to 124–139 year-old and plateaued, but in 7-year-old stands, CWD diversity was as high as that in the 124 and up year-old age classes. Logging resulted in a smaller amount and lower size variability of CWD in 7-year-old stands, with a larger portion being fast-decomposing Betula papyrifera. Most CWD characteristics had not converged by approximately 30 years since disturbance between the two stand origins. More diverse CWD occurred in mixedwoods, but conifer stands contained the greatest CWD volume except in 7 year-old postfire stands. [ABSTRACT FROM AUTHOR]

Abstract: Although the volume of dead wood is commonly acknowledged as an indicator of biodiversity in sustainable forest management schemes, only few data are available for plantation forests. To evaluate the volume and qualify the diversity of woody debris along a chronosequence of maritime pine plantations, we sampled downed woody debris, snags and stumps in 143 stands of different ages. To test the hypothesis that the pattern of dead wood accumulation mainly results from silvicultural operations, we developed a predictive model. It combined an empirical growth model evaluating the amount of dead wood produced by successive thinnings with a decay function that estimated the loss of dead wood with time. The volume of dead wood averaged 15m3/ha. Downed woody debris, stumps and snags represented 81%, 11% and 8% of this volume, respectively. Pieces of downed woody debris were equally distributed between fine and coarse woody debris however large pieces (diameter ≥20cm) were scarce. The dead wood was mainly from anthropogenic origin (77%) and its volume significantly increased with stand productivity. The pattern of dead wood accumulation along the forestry cycle showed a convex shape with a peak in stands of ca. 30-year-old, after the third thinning. The dynamics was successfully predicted for downed woody debris (r =0.47, P <0.001) and for stumps (r =0.45, P <0.001) by the model combining inputs from thinnings and loss with time. This model may help to predict the effect of alternative forestry practices on dead wood accumulation by forest managers or nature conservationists in similar pine forest plantations. [Copyright &y& Elsevier]

Abstract: In order to project the long-term implications of forest management for coarse woody debris (CWD) and its habitat-related ecological functions, the time frame of snag and downed woody debris (DWD) decomposition needs to be quantified. In the present study, we parameterized models of CWD decay class transitions that explicitly represent decomposition-related changes in white and red pine (Pinus strobus, P. resinosa) snags and DWD over time. Remeasurements of permanent sample plots in Ontario, Canada, were used to derive models of a tree''s condition at death (standing or fallen), snag fall rates, transitions among snag decay classes, and the entry of fallen snags into DWD decay classes. DWD decay class transitions were modelled from the condition of harvest residues across a 27-year chronosequence of shelterwood-harvested stands in central Ontario, and on the quasi-equilibrium decay class distribution of DWD in a series of relatively undisturbed sites. By combining these various model components, an integrated model of CWD decay class transitions was developed to project the condition of snags and DWD pieces over time. Projections showed that white and red pine snags had median fall times of 15–20 and 30 years, respectively. DWD from trees that fell at death was projected to advance through four decay classes over a 55–60-year period, whereas DWD originating from snags was modelled to persist for up to 90 years after tree death because of slower decomposition while standing. For both snags and DWD, decay classes I and II were short–lived relative to later classes. Diameter was found to have a significant effect on DWD transitions into decay classes II and IV but not III, with projections accordingly showing smaller-sized DWD to be less abundant in class III than larger material. Incorporating CWD dynamics such as those modelled here into stand growth and mortality models would enable managers to simulate long-term changes in the quality and quantity of snags and DWD under various forest management regimes, and to evaluate the degree to which CWD-associated habitat features may be maintained over time. [Copyright &y& Elsevier]

We studied the effects of the regeneration cut of the shelterwood system and four site preparation options on populations of eastern red-backed salamanders in 90–100-year-old white pine forests in central Ontario, Canada. We established the study in 1994 using a randomized complete block design with three replicates and five treatments: (1) no harvest, no site preparation; (2) harvest, no site preparation; (3) harvest, mechanical site preparation; (4) harvest, chemical site preparation; (5) harvest, mechanical and chemical site preparation. We applied harvest and site preparation treatments from fall 1995 to fall 1997. We collected pre-treatment data in spring and summer of 1995 and post-treatment data from 1998 to 2002. We monitored salamander abundance using a grid of 20 cover boards surveyed 10 times per year within each of the 15 treatment plots. We also quantified changes in overstory and understory cover, supply of downed woody debris, and disturbance to the forest floor. Our data suggest that shelterwood cutting and site preparation can have immediate negative effects on the abundance of red-backed salamander populations in pine forest. However, effects are relatively short lived (<5 years). Changes in abundance appeared to be related to overstory and understory cover, and forest floor disturbance. [Copyright &y& Elsevier]

Volume or biomass estimates of downed woody debris are crucial for numerous applications such as forest carbon stock assessment, biodiversity assessments, and more recently for environmental evaluations of biofuel harvesting practices. Both fixed-area sampling (FAS) and line-intersect sampling (LIS) are used in forest inventories and ecological studies because they are unbiased and accurate methods. Nevertheless, most studies and inventories take into account only coarse woody debris (CWD, >10 cm in diameter), although fine woody debris (FWD) can account for a large part of the total downed biomass. We compared the LIS and FAS methods for FWD volume or biomass estimates and evaluated the influence of diameter and wood density measurements, plot number and size. We used a Test Zone (a defined surface area where a complete inventory was carried out, in addition to FAS and LIS), a Pilot Stand (a forest stand where both LIS and FAS methods were applied) and results from 10 field inventories in deciduous temperate forest stands with various conditions and amounts of FWD. Both methods, FAS and LIS, provided accurate (in trueness and precision) volume estimates, but LIS proved to be the more efficient. Diameter measurement was the main source of error: using the mean diameter, even by diameter class, led to an error for volume estimates of around 35%. On the contrary, wood density measurements can be simplified without much influence on the accuracy of biomass estimates (use of mean density by diameter class). We show that the length and number of transects greatly influences the estimates, and that it is better to apply more, shorter transects than fewer, longer ones. Finally, we determined the optimal methodology and propose a simplification of some measurements to obtain the best time-precision trade-off for FWD inventories at the stand level. [ABSTRACT FROM AUTHOR]

Natural forest disturbance events can influence soil biogeochemical processes in two ways - by creating downed woody debris (DWD; fallen tree boles or branches) and by creating canopy gaps that alter forest microclimate. DWD represents a substrate for microbial growth and a persistent store of carbon and nutrients, but microbial activity is also sensitive to temperature and moisture. We studied the potential interaction of DWD and canopy gaps on soil microbial processes, and wondered if microclimatic conditions resulting from the manipulation of forest structure would be enough to inhibit production, thereby altering a critical ecosystem process. Gaps and DWD (>10 cm diameter) were added to a maturing, even-aged, second-growth northern hardwood forest (the Flambeau Experiment; N Wisconsin, USA) to enhance structural complexity and promote key ecosystem processes typically associated with late-successional forests. We investigated the influence of DWD and gaps on soil microbial community composition, extracellular enzyme activity and soil characteristics. Soils were sampled near intermediately and highly decayed DWD and 2 m away from DWD (control) in gaps and closed canopy a decade after manipulation. DWD decomposition influenced the surrounding soil differentially depending on decay class and canopy condition. Mean C- and P-potential extracellular enzyme activities (BG, BX and AP) were enhanced near highly decayed DWD in gaps. The relative abundance of bacteria (actinomycete, anaerobic, gram-negative and gram-positive) remained constant in gaps but decreased from May to August in closed canopy. In gaps, soil total exchangeable cations increased by 34.6%, available phosphorus by 152% and fungal to bacterial ratios by 23.3% but temperatures decreased by 3.42% suggesting that canopy condition continues to affect soil properties and microbial processes a decade after gap creation. These results highlight the contribution of DWD to the forest floor and the influence of decaying wood characteristics on belowground ecosystems critical to future forest productivity. Retaining or adding heterogeneously distributed DWD of varying decay status may be essential to maintain ecosystem functions associated with nutrient cycling and microbial community dynamics in managed forests. • Deadwood influenced soil differently depending on decay class and canopy condition. • Highly decayed wood enhanced soil C- and P- enzyme activities in canopy openings. • Canopy openings increased soil nutrient availability and fungal to bacterial ratios. • Soil bacterial abundance was more stable in open than closed canopy. [ABSTRACT FROM AUTHOR]

Coarse woody debris (CWD) is an important contributor to forest biodiversity because it provides essential habitat for saproxylic (dead wood‐dependent) species. However, CWD is frequently overlooked in forest management and restoration decisions around the world. We have therefore developed an index of CWD habitat quality that integrates four important characteristics of saproxylic habitat. We apply this index to wet eucalypt forests in Tasmania, Australia. The relationships between the CWD index and standing forest structural and floristic maturity metrics were weak (R2 < .09), highlighting the necessity to explicitly factor CWD habitat into conservation planning. A hump‐shaped relationship between current CWD habitat quality and variables linked to future quality (standing tree basal area and the number of old‐growth eucalypts) implies that stands with medium current quality provide better potential future habitat than stands with high current quality. CWD habitat quality was lower in previously harvested stands. We present a web app that calculates CWD habitat quality scores from raw field measurements. Our approach can be applied in conservation assessments to determine habitat availability for biodiversity, and to quantify the impacts of management actions and restoration activities. [ABSTRACT FROM AUTHOR]