Volume Of Woody Debris Research Articles

National parks in the easternUnitedStates harbor important older forest structure compared with matrix forests

AbstractWe analyzed land‐cover and forest vegetation data from nearly 25,000 permanent plots distributed across 50 national parks in the eastern United States, along with the matrix around each park, to examine structural characteristics of park forests in relation to their surrounding landscape. Over 2000 of these plots are part of the National Park Service (NPS) Inventory and Monitoring Program (I&M), and the remaining 22,500+ plots are part of the US Forest Service (USFS) Forest Inventory and Analysis (FIA) Program. This is the first study to compare forest structure in protected lands with the surrounding forest matrix over such a large area of the United States and is only possible because of the 10+ years of data that are now publicly available fromUSFS‐FIAandNPSI&M. Results of this study indicate that park forests, where logging is largely prohibited, preserve areas of regionally significant older forest habitat. Park forests consistently had greater proportions of late‐successional forest, greater live tree basal area, greater densities of live and dead large trees, and considerably larger volume of coarse woody debris. Park forests also had lower tree growth and mortality rates than matrix forests, suggesting different forest dynamics between park and matrix forests. The divergent patterns we observed between matrix and park forests were similar to those reported in studies that compared managed and old‐growth forests, although the differences in our study were less pronounced. With the majority of park forests in second growth, eastern parks may be a more realistic baseline to compare with the more intensively managed matrix forests. We recommend that park managers allow natural disturbance and the development of older structure to continue in park forests. In addition, long‐term maintenance of regional biodiversity will likely require increases in older forest structure in the matrix. As theNPSmoves into its next century of land preservation, we encourage managers to consider parks important components of a larger regional effort to preserve biodiversity and ecosystem processes in easternUSforests. The data collected byNPSI&M programs will continue to provide important information and guidance toward these regional conservation efforts.

Comparing Stream Restoration Project Effectiveness Using a Programmatic Evaluation of Salmonid Habitat and Fish Response

AbstractHundreds of millions of dollars have been spent on stream restoration projects to benefit salmonids and other aquatic species across the Pacific Northwest, though only a small percentage of these projects are monitored to evaluate effectiveness and far fewer are tracked for more than 1 or 2 years. The Washington State Salmon Recovery Board and the Oregon Watershed Enhancement Board have spent more than US$500 million on salmonid habitat restoration projects since 1999. We used a multiple before‐after–control‐impact design to programmatically evaluate the reach‐scale physical and biological effectiveness of a subset of restoration actions. A total of 65 projects in six project categories (fish passage, instream habitat, riparian planting, livestock exclusion, floodplain enhancement, and habitat protection) were monitored over an 8‐year period. We conducted habitat, fish, and macroinvertebrate surveys to calculate the following indicators: longitudinal pool cross section and depth, riparian shade and cover, large woody debris volumes, fish density, macroinvertebrate indices, and upland vegetation condition class. Results indicate that four categories (instream habitat, livestock exclusions, floodplain enhancements, and riparian plantings) have shown significant improvements in physical habitat after 5 years. Abundance of juvenile Coho Salmon Oncorhynchus kisutch increased significantly at fish passage projects and floodplain enhancement projects, but significant results were not detected for other fish species. Moreover, the biological response indicators of juvenile salmonid abundance and macroinvertebrate indices showed declines at instream habitat and habitat protection projects, respectively. Our results indicate that a subset of projects can be effectively evaluated programmatically, but power and sample size estimates indicate that two or more years of preproject data are necessary to adequately determine the effectiveness of many project types, particularly for fish. Programmatic evaluations of project effectiveness should include adequate preproject sampling and multiseason monitoring for fish species to address issues of variability that are likely to be encountered in large‐scale monitoring programs.Received September 16, 2015; accepted February 7, 2016 Published online June 6, 2016

The relative influence of in situ and neighborhood factors on reptile recolonization in post‐mining restoration sites

Restoration can be important in slowing, or reducing, rates of biodiversity loss, but needs to consider the factors influencing fauna recolonization as part of the recovery process. Although many studies of factors influencing faunal recolonization have examined the influence of in situ site factors, fewer have examined the influence of neighborhood landscape factors, especially in landscapes with permeable matrices. To assess the relative influence of landscape and site factors on reptile recolonization in a production landscape with a permeable matrix, we surveyed reptiles at intact reference sites and post‐mining restoration sites (3–20 years post‐mining [YPM]) in a forest ecosystem in southwestern Australia. Reptile assemblages in restoration sites never converged on those in reference habitat. Reptile species composition and individual species abundances (>20 detections) in restoration sites were primarily influenced by site factors such as canopy height, litter cover, and coarse woody debris volume, and not by landscape factors. We suggest that the most common reptile species in our study area are primarily influenced by site factors, not landscape factors, and most reptiles detected in restoration sites were present by 3–4 YPM. Therefore, it is likely that habitat suitability is the main barrier to most species' recolonization of restoration sites in landscapes with permeable matrices. Management should continue to focus on restoring microhabitats and vegetation structure, which is similar to reference habitat to promote recolonization of restoration sites by reptiles.

Factors influencing organic-horizon carbon pools in mixed-species stands of central Maine, USA

The overall goal of this study was to evaluate the correlation of multiple abiotic and biotic factors with organic-horizon (O-horizon) carbon (C) content on the Penobscot Experimental Forest in central Maine, USA. O-horizon samples were collected and their associated depths were recorded from stands managed with a range of silvicultural and harvesting treatments (i.e., selection, shelterwood, and commercial clearcut) and an unmanaged control. The overall mean for O-horizon C content from all samples was 25.6±16.1Mgha−1 (mean±SD). The samples were used to develop a pedotransfer function for predicting O-horizon C content from O-horizon depth (R2=0.47, RMSE=1.6Mgha−1) so that an average of O-horizon C content could be calculated for permanent sample plots on which abiotic and biotic factors were quantified. O-horizon depth measurements recorded along transects on permanent sample plots were used to calculate plot average O-horizon C content. There were no significant differences in average predicted O-horizon C content among selection, shelterwood, and commercial clearcut treatments. However, variation in predicted O-horizon C content between stands where the same treatment was applied was statistically significant and was likely due to the timing of harvests and abundance of dead wood buried within O horizons. Depth to redoximorphic features, cartographic depth to water table or saturated zone, drainage class, fine woody debris mass, downed woody debris volume, tree basal area, and the relative basal area of conifer species were not significant predictors of predicted O-horizon C content at the plot level. When the individual predicted values of O-horizon C content were modeled, within-plot variation accounted for 83.8% of the variance. Bryophyte mass, which was predicted from bryophyte cover, only explained 1.2% of the variation in O-horizon C content at the microsite level. These results highlight the sizeable variability in O-horizon C content within and among these mixed-species stands with various forest management and natural disturbance histories.

Forest restoration to attract a putative umbrella species, the white‐backed woodpecker, benefited saproxylic beetles

Umbrella species are often spatially demanding and have limited ability to adapt to environmental changes induced by human land‐use. This makes them vulnerable to human encroachment. In Sweden, broadleaved trees are disadvantaged by forestry, and commercially managed forests are often deprived of dead wood. This has led to a situation where previously widespread top predators in saproxylic food webs, such as the white‐backed woodpecker (Dendrocopos leucotos), have become species of conservation concern. The white‐backed woodpecker is generally considered an umbrella species, and it has been linked to forests with large volumes of dead wood from broadleaved trees. In recent years, forest stands have been restored for the white‐backed woodpecker, but post‐treatment evaluations have rarely included other species that also occur in broad‐leaved forests (co‐occurring species). Many co‐occurring species are saproxylic beetles. In this study, we collected saproxylic beetles and environmental data in restored and commercially managed forests to evaluate if habitat restoration for the white‐backed woodpecker also benefited other species with similar habitat associations. We found that volumes of coarse woody debris were higher in restored than in commercially managed forests, and that a majority of man‐made snags and downed logs were created from birch trees (Betula spp.). Most spruce trees (Picea abies) were extracted during forest restoration, and this opened up the forest canopy, and created stands dominated by broadleaved trees. Many saproxylic beetles were more common in restored forests, and there were significant differences in species composition between treatments. These differences were largely explained by species traits. Effects of sun‐exposure were particularly important, but many beneficiary species were also linked to dead wood from broadleaved trees. Red‐listed saproxylic beetles showed a similar pattern with more species and individuals in restored sites. The white‐backed woodpecker is still critically endangered in Sweden, but important prey species are already responding to forest restoration at the stand level. We recognize that landscape‐level improvements will be required to bring the white‐backed woodpecker back, but also that the umbrella species concept can provide a useful framework for successful forest restoration as many co‐occurring saproxylic beetle species seemingly benefitted from restoration for the white‐backed woodpecker.

Recreational activities impact on the amount and characteristics of woody debris in the Fandoghlou forests, Northwestern Iran

Abstract In this research, the volume and composition of woody debris (WD) were inventoried by line intersect sampling (LIS) in recreational and conservative parts of Fandoughlou forests in Northwestern Iran. Based on the pre-study qualitative assessments of WD properties, 60 transects in conserved part including 60 ha tract and 60 transects in recreational part including 60 ha and 60 transects were set up for WD survey. In each area, a systematic series of sampling points was located in the inventory of WD. At each sampling point, we performed line-intersect sampling (LIS) with a line length of 100 m with random orientation of sample lines. Estimates of the total volume of WD across recreational and conservative parts of the forest ranged from 0.70 m3 ha-1 to 1.49 m3 ha-1. The results of independent t-test indicated that the amount of CWD and FWD in conserved part is significantly higher than CWD and FWD in recreational part (t4, 0.05 = 4.26, p = 0.013; t4, 0.05 = 2.69, p = 0.05). The number of tree species of CWD composition was higher in conserved area, more than 5 species including (hazel, beech, hornbeam, oak, maple, and other species). In the conserved part, CWD in highly-decayed classes accounted for 75% of total CWD volumes, but in the recreational division, CWD in the early decayed classes accounted for 79% of total WD volumes. Our results suggest preserving the current conserved forests and maintaining the structural and functional integrity of WD.

Seasonal controls on patterns of soil respiration and temperature sensitivity in a northern mixed deciduous forest following partial-harvesting

Disturbances can alter CO2 efflux from soils (FCO2) by altering the microclimate, structure, and biogeochemical properties of forest ecosystems. Results of prior studies are unclear if and how partial harvesting of northern deciduous forests affects FCO2. These mixed responses may be due to differences in harvesting levels, time since harvest, and the spatial and seasonal heterogeneity of treatment effects and soil properties. To account for this spatio-temporal dependence, we produced subject-level regression models from regular measurements of FCO2 and soil temperatures during the 2010–2012 growing seasons following tree-length (TL) and more intensive biomass (BIO) harvests. In this paper, we compare seasonal and inter-annual post-harvest recovery trends for measured and temperature-corrected soil respiration rates and the sensitivity of soil respiration to temperature (as Q10).FCO2 values from TL/BIO treatments exceeded unharvested controls, recurrently peaking in the autumn (average for TL/BIO: 28%/17%, p⩽0.05) and waning in the summer (14%/10%, not significant). A comparison of measured FCO2 vs. modelled respiration values corrected for temperature differences indicated that higher soil temperatures following canopy thinning accounted for 34–41% of these differences in 2010 but <15% by 2012. Initially lower in 2010, Q10 and summer respiration values for harvested treatments exceeded those of controls by 2012, and despite waning temperature differences, average annual effect sizes corrected for temperature differences did not decline. Autumn and basal respiration rates were correlated with post-harvest fine woody debris volumes in 2010 (r2=0.58/0.57, p=0.01), summer rates in all years decreased with harvested tree basal area (r2=0.43–0.58, p⩽0.05), and the post-harvest basal area of understorey vegetation predicted increasing Q10 effect sizes from 2010 to 2012 (r2=0.81, p⩽0.01). With consideration to studies demonstrating that the contribution of root respiration (RR) to FCO2 is highest in summer, we propose that partial harvesting initially restricts RR and peak summer respiration rates, but compensates for this decline by increasing basal respiration rates and FCO2 through elevated soil temperatures and decomposition rates from canopy thinning and harvest residue substrate inputs (i.e., woody debris and root necromass). During post-harvest recovery, forest understorey regrowth reduces soil temperatures but influences patterns of FCO2 by increasing summer respiration and Q10 values in harvested treatments, likely by increasing RR.

Structural effects on understory attributes in second-growth forests of northern Wisconsin, USA

I sampled the understory and associated structural features in forty-four second growth forests of north-central Wisconsin, USA, to assess the influence of forest structure on four understory attributes: cover, richness, composition and evenness (variant of Simpson’s index). Eight structural features (overstory basal area and crown cover, percent conifer overstory, midstory basal area, shrub frequency, snag basal area, coarse woody debris volume, and maple seedling density) were measured. An additional derived variable, coefficient of variation (CV) for cover, was also tested. The objectives of the study were to determine the significance and impact (increase or decrease) of each structural feature on understory attributes. These were addressed with regression, canonical correspondence analysis, and two-sample tests. Ordination was used to assess differences in composition among forest types. The analyses indicated that structure had no effect on richness or cover, a modest influence on composition, and strong effect on evenness. An important revelation was the over-riding influence of understory structure, but a small role for the overstory. The severity and type(s) of historical disturbance interacted with species pools to strongly constrain richness in the early 20th century. Small changes related to succession have occurred since then. The amount of understory cover is still changing but appears to be succession-related. In contrast, more than 40% of the variation in evenness was explained by maple seedling density, and two interaction variables: maple density∗shrub frequency and overstory∗midstory basal area. Higher maple seedling density decreased evenness, probably by competitive effects. As the interaction variables increased, evenness was reduced. The regression analysis and CCA point to the shrub layer as having a direct, mechanistic effect on which species are present and their abundance; whereas the presence of shrubs is relatively benign. It is hypothesized that the abundance of upper strata resulted in varying levels of resource limitations, and influenced other environmental features to the extent that niche heterogeneity was affected. The proportion of conifer in the overstory had an important influence on understory composition, but hemlock assemblages did not differ from broadleaved forests in richness or cover. These results suggest that excess emphasis has been placed on the influence of the upper strata, but too little on the shrub and understory layers. Thus, the management of understory assemblages should carefully evaluate the sub-ordinate strata because they may be more important than upper layers.

Investigating the effects of forest structure on the small mammal community in frequent-fire coniferous forests using capture-recapture models for stratified populations

Small mammals comprise an important component of forest vertebrate communities. Our understanding of how small mammals use forested habitat has relied heavily on studies in forest systems not naturally prone to frequent disturbances. Small mammal populations that evolved in frequent-fire forests, however, may be less restricted to specific habitat conditions due to the instability of these resources in time and space. We investigate how canopy cover and the volume of coarse woody debris (CWD), covariates that are considered important for small mammals, impact abundance and body mass of eight small mammal species. Based on live-trapping data collected across 23 sites over three years in a frequent fire forest in the Sierra Nevada we apply capture-recapture models for stratified populations, a statistically rigorous, rarely used framework that allows joint modeling of detection, abundance and its response to covariates. Canopy cover had a strong negative association with the abundance of yellow-pine chipmunks and California ground squirrels, and a strong positive association with deer mice. CWD had a strong negative association with the abundance of golden-mantled ground squirrels, yellow-pine and long-eared chipmunks, and a strong positive association with deer mice. Whereas canopy cover influenced abundance and body mass similarly, CWD had a positive association with body mass and a negative association with abundance in some species. These patterns could arise if suitable habitat is monopolized by socially dominant individuals. Despite these habitat associations, the small mammal community in our study was dynamic and diverse, with spatial and temporal variation in dominant species suggesting that species were flexible in their use of habitat. This study suggests that it is important to understand the disturbance regimes when investigating habitat requirements, coexistence and evolutionary ecology of small mammal species.

Shrew response to variable woody debris retention: Implications for sustainable forest bioenergy

Shrews are integral components of forest food webs and may rely on downed woody debris to provide microhabitats that satisfy high moisture and metabolic requirements. However, woody biomass harvests glean downed woody debris to use as a bioenergy feedstock. Biomass Harvesting Guidelines (BHGs) provide guidance on the amount and distribution of downed woody debris retained after harvest to ensure ecological sustainability of woody biomass harvesting and limit detrimental effects on wildlife. However, the success of Biomass Harvesting Guidelines at reaching sustainability goals, including conservation of wildlife habitat, has not been tested in an operational setting. Thus, we compared shrew captures among six woody biomass harvesting treatments in pine plantations in North Carolina, USA from April to August 2011–2014 (n=4) and Georgia, USA from April to August 2011–2013 (n=4). Treatments included: (1) woody biomass harvest with no BHGs; (2) 15% retention with woody biomass dispersed; (3) 15% retention with woody biomass clustered; (4) 30% retention with woody biomass dispersed; (5) 30% retention with woody biomass clustered; and (6) no woody biomass harvested. We sampled shrews with drift fence arrays and compared relative abundance of shrews among treatments using analysis of variance. Additionally, we used general linear regression models to evaluate the influence of downed woody debris volume and vegetation structure on shrew capture success at each drift fence for species with >100 captures/state/year. In 53,690 trap nights, we had 1,712 shrew captures representing three species, Cryptotis parva, Blarina carolinensis, and Sorex longirostris. We did not detect consistent differences in shrew relative abundance among woody biomass harvest treatments, but relative abundance of all species increased over time as vegetation became established. In North Carolina, total shrew capture success was negatively related to volume of downed woody debris within 50m of the drift fence array (P=0.05) in 2013 and positively related to bare groundcover in 2013 (P=0.02) and 2014 (P<0.01). In Georgia, total shrew capture success was negatively related to herbaceous groundcover (P<0.01) and leaf litter groundcover (P=0.02) and positively related to woody vegetation groundcover (P<0.01) and vertical vegetation structure (P=0.03) in 2013. Our results suggest that shrews in our study area were associated more with vegetation characteristics than downed woody debris and that woody biomass harvests may have little influence on shrew abundances in the southeastern United States Coastal Plain.

A new tool for power analysis of fixed plot data: Using simulations and mixed effects models to evaluate forest metrics

Since 2006, the National Park Service's Northeast Temperate Network (NETN) has been monitoring forest health in 10 national park units in the northeastern U.S. using a protocol adapted from the U.S. Forest Service Forest Inventory and Analysis Program. To ensure current methods are appropriate for monitoring long‐term trends in forest composition, structure and function, we performed a power analysis of key forest metrics using data collected in each park and covering two four‐year survey cycles. We determined statistical power by repeatedly generating bootstrapped datasets with specified percent change between survey cycles in the value of each metric, and then testing whether a mixed effects model detected a significant change. We applied effect sizes ranging from a 50% decline to a 50% increase in 5% increments. Power analyses indicated that, for most key forest metrics, our monitoring program met the target of detecting a 40% change in a metric over a 12‐year period with 80% power and a Type I error rate of 0.10. Power also tended to improve with subsequent repeated surveys. Native species richness and live‐tree basal area metrics consistently performed well for all parks. Average percent cover of plant groups performed better than quadrat frequency. Regeneration metrics performed best in parks with low or high regeneration rates. Coarse woody debris volume, snag abundance, and invasive species richness did not meet the trend detection target in multiple parks. In most cases, metrics that failed to meet the trend detection target in one or several parks had high proportions of zeros and relatively low overall values for the respective park. In cases where high metric variability was the reason for poor trend detection, results indicated that post‐stratifying can sometimes improve power. We developed the power analysis tool in R to be applicable for a range of data types, including proportional and count data, and for any number of sampling areas (e.g., parks) and sampling units (e.g., plots). Our approach represents one of the few tools available that can assess the power to detect change over time using mixed effects models.

Multi-scale assessment of habitats and stressors influencing stream fish assemblages in the Lake Pontchartrain Basin, USA

This study determined if a spatial hierarchy existed with respect to reach-scale habitat, subwatershed-scale, and watershed-scale geomorphology and land use stressors on fish assemblages in southeastern U.S. coastal plain streams. During May–October 2009–2012, fishes were sampled by seine, and habitat was assessed at 50 reaches in the Lake Pontchartrain Basin (USA). Using partial redundancy analysis (pRDA) a variance decomposition procedure was used to partial out influences of confounding covariables at each spatial scale. Reach-scale habitat had the strongest association with the assemblage. Stream width, depth, aquatic vegetation and human debris cover, rapid habitat assessment score, and large woody debris volume were the most important variables. At subwatershed and watershed scales, natural and anthropogenic characteristics were important, including elevation, gradient, watershed area, wetland cover, stream density, road, dam and oil/gas well densities. Six species were associated most strongly with the watershed variables, compared to reach- and subwatershed-scale variables. These species had more “r-selected” life-history strategies (e.g., smaller eggs, shorter life spans, multiple broods, longer spawning season, and trophic generalists). In contrast, most species that were associated strongest with reach-scale variables exhibited more “k-selected” life-history traits (e.g., larger eggs, longer life spans, shorter spawning season, single brood, and trophic specialists).

Contrasting Effects of Wildfire and Ecological Restoration in Old-Growth Western Larch Forests

The scientific basis for restoration of fire-excluded western larch/mixed-conifer forests is not as well developed as that for dry fire-frequent forests. We compared the effects of wildfire and restoration (combined thinning and prescribed fire) in fire-excluded western larch forests. In 2012, the wildfire site had more, taller, and more diverse tree regeneration; greater volume of coarse woody debris (CWD); and greater spatial heterogeneity (including more area in large openings) than the restoration site. Management recommendations based on our results include the following: use more intense prescribed fire than was applied to the restoration site we studied; retain abundant CWD on-site after restoration treatment; and create occasional large openings to regenerate larch and emulate the spatial heterogeneity induced by natural wildfire. Our most important finding is the greater dynamism of the wildfire-affected site than of the restored site. At the wildfire site, tree populations are turning over faster, regenerating trees are growing faster, and more CWD is available for decomposition. These contrasting outcomes suggest that a conceptualization of forest restoration that emphasizes static, or at least equilibrium, conditions is not appropriate for western larch/mixed-conifer forests.

Patterns of coarse woody debris volume among 18 late-successional and mature forest stands in Pennsylvania1

Coarse woody debris (CWD) provides vital habitat and resources for a broad variety of organisms in old-growth stands. Although many studies have quantified CWD, it remains unclear how variability in tree species composition relates to CWD and snag volume. If CWD and snags (standing dead trees) vary substantially with tree species abundance among different forest types, then the volume of CWD may change in response to shifts in tree species composition. Dominant canopy tree species vary significantly in their decay resistance, shade tolerance, and suppression of light transmission through the canopy; therefore, the rate of CWD input and output may vary with dominant tree species abundance. We hypothesize that CWD and snag volumes are positively related to the abundance of late-successional shade-tolerant canopy species and negatively related to the abundance of mid-successional oak species. To test this hypothesis, CWD was surveyed in 18 late-successional and mature stands across three physiographic provinces in Pennsylvania. The stands were classified by composition: ten as red oak-mixed hardwood and eight as hemlock-mixed hardwood. The hemlock-mixed hardwood stands (vs. the oak-mixed hardwood stands) had larger volumes of CWD and higher relative abundance of shade-tolerant species. CWD volume was positively correlated with the basal area of hemlock and all shade-tolerant species combined. In contrast, basal area of oak species was negatively correlated with the volume of snags and CWD. These results supported the hypothesis that CWD volume is greater in stands dominated by late-successional species, particularly hemlock, than in stands dominated by oak species. The volume of CWD did not change significantly with the abundance of any other tree species (e.g., red maple (Acer rubrum L.), beech (Fagus grandifolia Ehrh.)). Understanding the relationship between tree species composition and the volume of CWD and snags can provide insight into future CWD characteristics as pathogens dramatically change eastern forests (e.g., beech bark disease, hemlock woolly adelgid).

Voles, trees, and woody debris structures as habitat: Balancing forest crop protection and biodiversity

Relatively homogeneous early successional habitats develop after clearcutting and wildfire that voles of the genera Microtus and Myodes may colonize and generate population fluctuations. In these habitats, vole populations may reach pest status by their feeding on newly planted tree seedlings. Strategic management of excess woody debris into piles and windrows helps diversify new clearcuts by enhancing populations of forest-floor small mammals, including voles, and some of their predators.This study tested the hypotheses (H) that (H1) abundance of voles and incidence of feeding damage to tree seedlings will be higher in windrow than dispersed (conventional) sites of woody debris, and (H2) there will be a gradient of damage with the highest incidence immediately adjacent to windrows. A third hypothesis (H3) predicts that feeding damage to trees will increase in relation to windrow size. Microtus voles and red-backed voles (Myodes gapperi) were live-trapped for three years (2010–2012) in replicated sites with woody debris dispersed and in windrows at three study areas in the southern interior of British Columbia, Canada. Incidence of feeding damage and mortality to tree seedlings by voles was measured in all sites. Mean abundance of M. gapperi, Microtus, and total voles were all significantly (P ≤ 0.04) higher (up to 3.4 times) in windrow than dispersed sites, and hence the abundance part of H1 was supported. Mean annual percentage of trees damaged by voles was significantly (P ≤ 0.03) higher in windrow than dispersed sites over the two winters and for cumulative incidence of damage, and hence the tree damage part of H1 was supported. Mortality of trees followed this pattern but was not formally significant. Trees planted immediately adjacent to a windrow had significantly (P < 0.01) greater feeding damage than seedlings planted further away, and hence H2 was supported. There were significant linear relationships between mean percentage of trees killed (r = 0.67; P < 0.01) and mean number of total voles, and also with mean volume of woody debris per meter length of windrow (r = 0.98; P < 0.01). Thus, H3 was also supported. To minimize overall mortality of trees, it is likely worthwhile to not plant trees near windrows. Slightly reduced stocking (<5% net forest area) and potential loss of some trees to voles need to be balanced alongside biodiversity and conservation considerations provided by woody debris structures.

Effect of improvement cutting on the community structure of aphyllophoraceous fungi on Okinawa Island

Improvement cutting, which decreases tree density by cutting and thinning while leaving logging residues, has been practiced on Okinawa Island since the 1970s and changes not only the vegetation composition but also the amount and composition of woody debris on the forest floor. To quantitatively compare the effect of improvement cutting with the effects of woody debris and vegetation on the community structure of aphyllophoraceous fungi, we conducted a field survey of vegetation composition, the amount and composition of woody debris, and the aphyllophoraceous fungi flora on Okinawa Island in December 2006. We established 3 plots in forest stands without logging and 13 plots in a forest that had undergone improvement cutting from 1 to 22 years before our field survey. The number and volume of woody debris tended to be highest soon after improvement cutting. We recorded 1,172 fungal samples belonging to 81 species in four orders. Fungal species richness was correlated with the composition of the woody debris. Fungal species composition in forest plots 1 year after improvement cutting differed from most of the other logged forests. Variation partitioning revealed that the effects of improvement cutting explained 14.1 % of the total variation in fungal species composition, and that differences in woody debris and vegetation not related to improvement cutting explained 40.4 %. Changes in the composition of woody debris caused by improvement cutting explained at most 2.7 % of the variation. This suggests that improvement cutting does not have a strong effect on fungal community structure, but woody debris does.

Patterns of Riparian and In-stream Large Woody Debris Across a Chronosequence of Southern Appalachian Hardwood Stands

ABSTRACT: The density and volume of riparian and in-stream large woody debris (LWD) is hypothesized to be a function of forest disturbance and developmental processes. However, these relationships are poorly understood for many forest types, including hardwood forests of the southern Appalachian Highlands. We analyzed patterns of riparian and in-stream LWD in hardwood stands across three establishment classes (pre-1900s, 1930s, and 1950s) on the Cumberland Plateau to elucidate the relationships between forest development and LWD patterns. The stands were dominated by Fagus grandifolia, Quercus alba, and Lirodendron tulipifera. Density and volume of riparian LWD did not differ across the chronosequence. Density of riparian LWD ranged from 367 (1950s) to 407 (1930s) pieces ha-1 and volume ranged from 142.0 (pre-1900s) to 187.1 (1930s) m3 ha-1. Likewise, mean density and volume of in-stream LWD did not differ across the chronosequence. Density of in-stream LWD ranged from 20 pieces 100 m-1 (pre-1900s and 195...

Diversifying clearcuts with green-tree retention and woody debris structures: conservation of mammals across forest ecological zones

We tested the hypotheses (H) that on newly clearcut-harvested sites, (H1) abundance and species diversity of the forest-floor small mammal community, and (H2) abundance, reproduction, and recruitment of red-backed voles ( Vigors), would increase with higher levels of structural retention via green-tree retention (GTR) and woody debris (dispersed and constructed into windrows). Study areas were located in three forest ecological zones in southern British Columbia, Canada. For H1, mean total abundance did generally increase with the gradient of retained habitat structure. Mean species richness and diversity were similar among treatment sites but did show an increasing gradient with structural compexity. For H2, mean abundance, reproduction, and recruitment of were higher in GTR and windrow sites than those without retained structures. There was a positive relationship between mean abundance of and total volume of woody debris across treatments. This study is the first investigation of the responses of forest-floor small mammals to an increasing gradient of retained habitat structure via GTR and woody debris on clearcuts. Our assessment of a combination of these two interventions suggested a potentially strong additive effect that could be cautiously extrapolated across three forest ecological zones. With the advent of low levels of GTR on clearcuts, woody debris structures should help provide some habitat to conserve forest mammals on harvest openings.Myodes gapperiM. gapperiM. gapperi

Millennial stocks and fluxes of large woody debris in lakes of the North American taiga

Summary Large woody debris (LWD) is an important cross‐boundary subsidy that enhances the productivity of lake ecosystems and the stability of aquatic food webs. LWD may also be an important carbon sink because LWD pieces are preserved for centuries in the littoral zone of lakes and rivers. However, a long‐term analysis of LWD stocks and fluxes in lakes, coupled with the reconstruction of past disturbances at the site level, has never been attempted. Large woody debris was sampled in five lakes of the Quebec taiga. Actual LWD stocks were described and residence time of the LWD pieces was established using tree‐ring and radiocarbon dating. LWD losses by decomposition and burial and other factors influencing LWD residence time were investigated using linear regressions. Impacts of wildfires on LWD fluxes during the last 1400 years were reconstructed separately for the five lakes using piecewise regression models. Fire years at each site were identified from the recruitment dates of charred LWD pieces. Large woody debris volume ranged between 0.92 and 1.57 m3 per 100 m of shoreline, and extrapolating these results to the landscape scale, it was concluded that LWD littoral carbon pools represent a minimal portion of boreal carbon storage. Large woody debris residence time in boreal lakes was confirmed to be very long. Tree‐ring dates of 1571 LWD pieces, mainly black spruce (Picea mariana (Mill.) BSP.), spanned the last 1400 years, while LWD specimens of older floating chronologies were preserved from decomposition for up to five millennia. The most influential variables explaining the variation in LWD residence time were the degree of burial and the distance from the shore. Large woody debris recruitment rates averaged 5.8 pieces per century per 100 m of shoreline. Fourteen wildfires were the primary cause for changes in the rates of tree establishment in the riparian forests and of LWD recruitment in the lakes. Synthesis. Interactions between terrestrial and aquatic ecosystems in northern boreal regions are strongly influenced by wildfires whose effects can last for centuries due to the slow large woody debris decay rate. Actual LWD stocks and carbon pools are a legacy of the past fire history.

Characteristics of small mammal populations in thinned and clearcut stands in Japanese larch (Larix leptolepis) plantations

The goal of this study was to gain an understanding of small mammal populations in thinned and clearcut stands in Japanese larch (Larix leptolepis) plantations on Mt. Maehwasan, Hongcheon, Korea. Foliage profiles, diameter at breast height distribution, coverage of ground, and volume of coarse woody debris were significantly different between thinned and clearcut stands. Total number of captured small mammals, number of captured striped field mice, and mean striped field mouse population densities obtained from Jolly–Seber estimates were higher in clearcut stands. Coverage of ground, volume of coarse woody debris, and number of downed trees were critical variables for abundance of small mammals in this study. Our results suggest that retention of coarse woody debris and downed trees prevent reduction of small mammal populations after forest practices in Japanese larch plantations.