Coarse Woody Debris Removal Research Articles

Douglas-Fir Biomass Allocation and Net Nutrient Pools 15–20 Years after Organic Matter Removal and Vegetation Control

Douglas-fir (Pseudotsuga menziesiivar. menziesii (Mirbel) Franco) plantation forests of the coastal Pacific Northwest have been intensively managed to improve the yield of forest products. However, the long-term effects of these management techniques have received limited research attention in this region. Three affiliate Long-Term Soil Productivity study sites were installed in Douglas-fir forests to understand the impacts of organic matter removals and vegetation control on soil productivity over time. Matlock and Fall River are located in Washington, USA and Molalla is located in Oregon. Organic matter removal treatments included traditional bole-only harvest (BO), whole tree removals (WT), and a whole tree plus coarse woody debris removal (WT+) (Fall River only). Five years of annual vegetation control (AVC) was compared with a conventional initial vegetation control (IVC) treatment at all sites. Douglas-fir biomass allocation to foliage, branch, and stem components was modeled using 15- to 20-year-old trees from this study along with 5- to 47-year-old trees from previous studies on these sites. Across all sites, model predictions indicated that the WT treatment had 7.1 to 9.7 Mg ha−1 less Douglas-fir biomass than the BO treatment. There was 1.5 to 20.5 Mg ha−1 greater Douglas-fir biomass in the AVC treatment than in the IVC treatment at all sites. Douglas-fir carbon and nitrogen biomass were consistently lower in the WT treatment, but there were no significant changes in overall site nutrient pools. The AVC treatment resulted in greater Douglas-fir nutrient pools yet there was a net loss in site calcium, magnesium, and potassium due to lower forest floor and soil base cation pools. While WT removals did not significantly affect site nutrition, the decrease in Douglas-fir biomass at all sites and increase in invasive Scotch broom (Cytisus scoparius (L.) Link) biomass at Matlock suggests that the standard practice of retaining harvest residuals is beneficial. The use of intensive vegetation control to improve Douglas-fir biomass and nutrition must be balanced with retaining soil base cations.

Impacts of organic matter removal and vegetation control on nutrition and growth of Douglas-fir at three Pacific Northwestern Long-Term Soil Productivity sites

As intensive management of forest plantations and interest in harvesting biomass for energy continue to increase, there is a need to investigate the longer-term effects of harvest-related disturbances and intensive treatments on soil and site productivity. This research focused on three Pacific Northwestern Douglas-fir soil productivity studies around 15 years since harvest that spanned a range in soil nutrients: high soil N and low base cations (Fall River), low soil N and base cations (Matlock), and high soil N and base cations (Molalla). The studies, which had similar organic matter and vegetation control treatments, were compared for differences in belowground and aboveground nutrients as well as differences in periodic stand volume growth. Five years of annual vegetation control (AVC) resulted in the greatest losses of belowground N and base cations compared to one year of vegetation control (IVC) at planting, but also resulted in significantly greater stand volume growth at Fall River and Matlock. Whole tree removal (WT) resulted in lower soil NO3− at Fall River but greater soil NO3− at Matlock due to greater colonization by N-fixing Scotch broom. There was also a decrease in soil exchangeable K due to WT and WT plus coarse woody debris removal (WT + ) at Fall River, which had the lowest initial soil exchangeable K. There was either no effect (Matlock and Molalla) (0–15 years) or a decrease (Fall River) (0–5 years) in stand volume growth due to WT removal. At Fall River, WT, WT+, and AVC treatments had no detectable effect on volume growth from 10 to 15 years. Overall, longer-term effects of organic matter removals and vegetation control on soil and site productivity were variable at each site due to pre-treatment soil nutrition and competition from understory vegetation.

Dead wood resources vary across different types of urban green spaces and depend on property prices

Dead wood provides important ecosystem services and has a positive effect on biodiversity. However, urban environments have limited resources of coarse woody debris (CWD). The presence of CWD depends on both progressive tree mortality and the frequency and intensity of CWD removal for safety or aesthetic reasons, which can lead to variations in CWD occurrence. The aim of this study was to assess the variation in the quantity and quality of CWD in urban green spaces and to assess the relationship between CWD resources and management policy, ownership, economic parameters and factors accelerating tree mortality. Fallen logs, dead standing trees and dead tree branches (DTB) were surveyed on 488 sample plots selected at random in the city of Kraków (Poland). Distance to the river, coverage of impervious surfaces, environmental pollution, property prices and types of green space were used to explain the variation in CWD resources. CWD occurred on 46% of the sample plots. DTB were the most frequent form of CWD (44% of plots), while dead standing trees were rare (4%) and fallen logs absent. The prevalence of CWD was the highest in forest remnants, followed by private gardens, urban parks, fallow land and small green patches. DTB were the most abundant in the forest remnants. In both forest remnants and private gardens, the probability of CWD occurrence decreased with increasing property prices. Management policy and economy rather than factors accelerating tree mortality are suggested as shaping CWD resources in urban green spaces. The article highlights the importance of DTB as the most widespread form of CWD and forest remnants as the type of green space having the most abundant resources of CWD. Sustainable management of CWD resources within urban green spaces and environmental education are needed to conserve biodiversity and maintain ecosystem services.

Variable responses of non-native and native ants to coarse woody debris removal following forest bioenergy harvests

Timber harvests may facilitate ant invasions of forested landscapes, fostering interactions between non-native and native ants. Harvests that include removal of low-value woody biomass as forest bioenergy feedstock may reduce residual coarse woody debris, thereby altering food and cover resources for ant species. We manipulated: (1) volume and distribution of coarse woody debris in stand-scale treatments ranging from intensive coarse woody debris removal to no coarse woody debris removal; and (2) coarse woody debris availability at microsite locations within stand-scale treatments, including piles of hardwood stems, piles of conifer stems, and no pile locations in North Carolina, USA and windrows (i.e., long, linear piles of harvest residues) and no windrows in Georgia, USA, in recently clearcut pine plantations (n = 4 per state). We captured ants in regenerating stands and tested treatment- and location-level effects on non-native and native ant relative abundances. Invasive ants represented 19% of ant taxa richness, but comprised 94% of total ant captures. Red imported fire ant (Solenopsis invicta Buren, hereafter “RIFA”) dominated the ant community in young plantations. RIFA avoided windrows, but its relative abundance did not differ among stand-scale treatments. Coarse woody debris retention in stand-scale treatments and at microsite locations favored non-RIFA ants, including Asian needle ant (Brachyponera chinensis Emery) and several native ant species. Dual invasions of RIFA and Asian needle ant in young plantations of the eastern United States may commonly occur because the two species may not compete for resources on the forest floor. Reduction of coarse woody debris via intensified woody biomass harvesting may negatively affect non-RIFA ant species and promote RIFA colonization, thereby indirectly increasing deleterious effects of RIFA on other wildlife.

Invertebrate community response to coarse woody debris removal for bioenergy production from intensively managed forests.

Increased market viability of harvest residues as forest bioenergy feedstock may escalate removal of coarse woody debris in managed forests. Meanwhile, many forest invertebrates use coarse woody debris for cover, food, and reproduction. Few studies have explicitly addressed effects of operational-scale woody biomass harvesting on invertebrates following clearcutting. Therefore, we measured invertebrate community response to large-scale harvest residue removal and micro-site manipulations of harvest residue availability in recently clearcut, intensively managed loblolly pine (Pinus taeda) forests in North Carolina (NC; n=4) and Georgia (GA; n=4), USA. We captured 39,794 surface-active invertebrates representing 171 taxonomic groups using pitfall traps situated among micro-site locations (i.e., purposefully retained piles of hardwood stems and piles of conifer stems and areas without coarse woody debris in NC; windrows and no windrows in GA). Micro-site locations were located within six, large-scale treatments (7.16-14.3ha) in clearcuts. Large-scale treatments represented intensive harvest residue removal, 15% and 30% harvest residue retention, and no harvest residue removal. In NC, ground beetles (Coleoptera: Carabidae) and crickets (Orthoptera: Gryllidae) were three times more abundant in treatments with no harvest residue removal than those with the most intensive harvest residue removal and were reduced in treatments that retained 15% or 30% of harvest residues, although not significantly. Invertebrate taxa richness was greater at micro-site locations with retained hardwood and pine (Pinus spp.) harvest residues than those with minimal amounts of coarse woody debris. In both states, relative abundances of several invertebrate taxa, including cave crickets (Orthoptera: Rhaphidophoridae), fungus gnats (Diptera: Mycetophilidae and Sciaridae), millipedes (Diplopoda), and wood roaches (Blattodea: Ectobiidae), were greater at micro-site locations with retained harvest residues than those with minimal coarse woody debris. Intensified woody biomass harvesting without retention of ≥15% of harvest residue volume may reduce invertebrate taxa richness and abundances of some key invertebrate taxa in regenerating stands. Further, harvest residue management during and after woody biomass harvesting may be an important consideration for maintaining invertebrate diversity and conserving invertebrates that are influential in the maintenance of ecosystem function and integrity in young forests.

Effects of logging and coarse woody debris harvest on lepidopteran communities in the eastern deciduous forest of North America

Expansion of biomass energy production using woody feedstocks is being accomplished through post-timber harvest removal of coarse woody debris > 10 cm. The effect of this management on forest Lepidoptera is poorly known. The present study aimed to determine whether forest lepidopteran diversity and species composition were affected by two silvicultural disturbances: timber harvest and post-logging removal of coarse woody debris > 10.0 cm in diameter. In 2014, Lepidoptera were sampled from nine forest stands subject to one of three management treatments: control (no manipulation at all), clear cut and partial retention of coarse woody debris (80% removal), and clear cut and complete removal of coarse woody debris. As expected, species richness and composition were significantly impacted by timber harvest. Subsequent removal of 80% or 100% coarse woody debris, however, did not affect specialists, detritivores and pollinators. The absence of an effect as a result of the removal of coarse woody debris could be a result of the limited number of replicate stands, small stand size and the limited range of retention treatments. We suggest, however, that retention of fine woody debris with a diameter < 10.0 cm and inclusion of unlogged stands in the forest landscape maintains some of the habitat elements necessary for Lepidoptera.

Coarse Woody Debris Stimulates Soil Enzymatic Activity and Litter Decomposition in an Old-Growth Temperate Forest of Patagonia, Argentina

In most temperate forest ecosystems, tree mortality over time generates downed logs that accumulate as coarse woody debris (CWD) on the forest floor. These downed logs and trunks have important recognized ecosystem functions including habitat for different organisms and long-term organic C storage. Due to its recalcitrant chemical composition and slow decomposition, CWD can also have direct effects on ecosystem carbon and nutrient turnover. CWD could also cause changes indirectly through the physical and chemical alterations that it generates, although it is not well-understood how important these indirect effects could be for ecosystem processes and soil biogeochemistry. We hypothesized that in an old-growth mature forest, CWD affects carbon and nutrient cycles through its “proximity effects”, meaning that the forest floor near CWD would have altered soil biotic activity due to the environmental and biogeochemical effects of the presence of CWD. We conducted our study in an old-growth southern beech temperate forest in Patagonia, Argentina, where we estimated and classified the distribution and mass, nutrient pools and decay stage of CWD on the forest floor, and evaluated its impact on litter decomposition, soil mites and soil enzymatic activity of carbon and phosphorus-degrading enzymes. We demonstrate here that CWD in this ecosystem represents an important organic carbon reservoir (85 Mg ha−1) and nitrogen pool (0.42 Mg ha−1), similar in magnitude to other old-growth forests of the Northern Hemisphere. In addition, we found significant proximity effects of CWD, with increased C-degrading soil enzyme activity, decreased mite abundance, and more rapid litter decomposition beneath highly decayed CWD. Considered at the ecosystem scale in this forest, the removal of CWD could cause a decrease of 6% in soil enzyme activity, particularly in the summer dry season, and nearly 15% in annual litter decomposition. We conclude that beyond the established importance of CWD as a long-term carbon reservoir and habitat, CWD contributes functionally to the forest floor by influencing the spatial heterogeneity of microbial activity and carbon and nutrient turnover. These proximity effects demonstrate the importance of maintenance of this ecosystem component and should be taken into consideration for management decisions pertaining to carbon sequestration and functional diversity in natural forest ecosystems.

Coarse woody debris retention in subalpine clearcuts affects ectomycorrhizal root tip community structure within fifteen years of harvest

Shifts in ectomycorrhizal (ECM) fungal community composition occur after clearcut logging, resulting in the loss of some dominant forest fungi. Because decaying wood is a remnant of the original forest and an important habitat for ECM fungal species, we examined ECM spruce roots and hyphae in 1-ha coarse woody debris (CWD) retention and removal plots (N=3) at a high elevation spruce forest 12 and 13 years after clearcut harvesting to test for a medium-term effect of CWD retention. Root tips from ten Picea engelmannii (Parry ex. Engelm.) saplings per plot were grouped morphologically, and the ECM fungal symbiont identified by Sanger sequencing. Sand-filled hyphae-trapping mesh bags were buried amongst the roots of saplings for one year. PCR product from all bags per plot was pooled and submitted for GS-FLX Titanium sequencing. Forty-six of 89 operational taxonomic units (OTUs) from root tips and 50 OTUs from hyphae were identified as ECM taxa. The most abundant taxa amongst root tip OTUs were Thelephora terrestris, Alloclavaria purpurea, Amphinema byssoides, and Tylospora asterophora. The most abundant OTUs from mesh bags were ectomycorrhizal taxa, and the most abundant of these were A. byssoides, T. terrestris, Wilcoxina mikolae, and T. asterophora. The retention of CWD had no detectable effect on taxon richness, evenness or diversity of ECM fungi on root tips or in mesh bags; however, there was a detectable shift in species composition. The relative abundance of A. byssoides root tips was significantly higher at removal plots while A. purpurea was a significant indicator species for CWD removal. Our results suggest that the retention of CWD at the time of harvest has affected ECM habitat at this site, and has resulted in altered ECM species composition, even though the logs are still hard and intact.

Ecological consequences of dead wood extraction in an arid ecosystem

Coarse woody debris (CWD) plays a key role in ecosystems, reducing erosion and affecting soil development, storing nutrients and water, providing a major source of energy and nutrients, serving as a seedbed for plants and as habitat for decomposers and heterotrophs. We asked whether removal of CWD affected the structure and functioning of an arid woodland ecosystem in mid-western Argentina. These woodlands are protected by national laws and inhabited by indigenous local pastoralists who have land rights to use natural resources, including wood for fuel and construction material. We hypothesized that removal of CWD affected negatively the populations of wood-nesting pollinators, the reproductive performance of Prosopis flexuosa (the dominant tree species), plant cover, richness and composition, and nutrient cycling in the soil. We conducted a manipulative experiment consisting of four pairs of 70 m radius circular plots, each pair with an experimental (CWD removal) and a control (no removal) plots. Experimental CWD extraction affected negatively flower visitor abundance, although the magnitude of this effect decreased over time. In contrast, extraction had a significant, positive effect on seed production of P. flexuosa. No significant effects of extraction were found on cover, richness and composition of understory plants and soil properties. Thus, CWD did not have the generally negative effects expected under our hypotheses.

Influence of fallen coarse woody debris on the diversity and community structure of forest-floor spiders (Arachnida: Araneae)

Purely observational studies have documented differences in the abundance and diversity of several litter-dwelling arthropods between sites adjacent to, and far from, CWD, which suggests that reduction of fallen coarse woody debris (CWD) in temperate forests by traditional forestry practices may affect the litter arthropod community. As few field experiments have directly tested the impact of CWD on arthropods inhabiting the litter at different distances from CWD, we removed CWD from replicated open plots on the floor of a second-growth deciduous forest in order to reveal the causal connection between CWD and litter-dwelling spiders, often the most diverse and abundant predators among the litter macrofauna of temperate forests. We also documented the impact of the CWD manipulation on spider prey and several other major macroarthropod groups. Before removing CWD (∅ = 14.3 ± 0.7 cm), we measured response variables as a function of distance (0.5–1.5 m) from CWD in both removal and control plots. In agreement with results of previous research that solely utilized this observational approach in temperate forests, volume and dry mass of litter, spider diversity, overall spider density, and densities of 8 of 16 major spider genera were higher adjacent to CWD before experimental manipulations. Removing CWD reduced the amount of litter and the density of spiders in litter close to where the CWD had been. Removing CWD also altered spider community structure, which had differed between litter sites adjacent to, and far from, CWD prior to the experimental removal of CWD. The patterns, though, were not completely congruent, as some of the taxa affected by the manipulation had not differed between sites prior to the removal of CWD, and vice-versa. Our findings suggest that complex interactions among structural, biotic and microclimatic factors underlie the observed responses to CWD removal by spiders and other arthropods in the litter layer. We also conclude that drawing inferences solely from observational studies is not a reliable approach for predicting the impact of changes in the amount of CWD on arthropods of forest-floor leaf litter. Further field experiments manipulating different volumes of CWD are needed in order to determine the minimum amount of CWD that should be kept on the forest floor of managed forests in order to maintain densities and diversities of major leaf-litter arthropods.

Amphibian and reptile community response to coarse woody debris manipulations in upland loblolly pine ( Pinus taeda) forests

Coarse woody debris (CWD) has been identified as a key microhabitat component for groups that are moisture and temperature sensitive such as amphibians and reptiles. However, few experimental manipulations have quantitatively assessed amphibian and reptile response to varying CWD volumes within forested environments. We assessed amphibian and reptile response to large-scale, CWD manipulation within managed loblolly pine stands in the southeastern Coastal Plain of the United States from 1998 to 2005. Our study consisted of two treatment phases: Phase I treatments included downed CWD removal (removal of all downed CWD), all CWD removal (removal of all downed and standing CWD), pre-treatment snag, and control; Phase II treatments included downed CWD addition (downed CWD volume increased 5-fold), snag addition (standing CWD volume increased 10-fold), all CWD removal (all CWD removed), and control. Amphibian and anuran capture rates were greater in control than all CWD removal plots during study Phase I. In Phase II, reptile diversity and richness were greater in downed CWD addition and all CWD removal than snag addition treatments. Capture rate of Rana sphenocephala was greater in all CWD removal treatment than downed CWD addition treatment. The dominant amphibian and snake species captured are adapted to burrowing in sandy soil or taking refuge under leaf litter. Amphibian and reptile species endemic to upland southeastern Coastal Plain pine forests may not have evolved to rely on CWD because the humid climate and short fire return interval have resulted in historically low volumes of CWD.

Recruitment dynamics of invasive species in rainforest habitats following Cyclone Larry

Abstract In tropical forests, natural disturbance creates opportunities for species to claim previously utilized space and resources and is considered an important mechanism in the maintenance of species diversity. However, ecologists have long recognized that disturbance also promotes exotic plant invasions. Cyclones cause extensive defoliation, loss of major branches and multiple tree falls, resulting in a significantly more open canopy and increased light and heat levels in the understorey. The widespread and massive disturbance caused by cyclones provides ideal conditions for rapid recruitment and spread of invasive species. The ecological roles of invasive species in rainforest habitats following such a severe disturbance are poorly understood. Severe category 4 Cyclone Larry crossed the North Queensland coast in March 2006 causing massive disturbance to rainforest habitats from Tully to Cairns and west to the Atherton Tablelands. We established 10 plots in an area extensively damaged by this cyclone near El Arish in North Queensland. On each plot nine 2 × 2 m quadrats were established with three quadrats per plot in each of the following treatments: (i) complete debris removal down to the soil layer, (ii) removal of coarse woody debris only, and (iii) uncleared. We monitored recruitment, growth and mortality of all native and invasive species in the 90 quadrats every 3 months since the cyclone. Here we present the recruitment dynamics of invasive species across the study area in relation to the level of disturbance, the type of quadrat treatment, and the diversity and abundance of the native recruiting flora over the first 12 months post‐cyclone. Our results suggest that invasive species will mostly comprise a transient component of the flora in the early stages of the successional response. However, some species may have longer‐term effects on the successional trajectory of the rainforest and future forest composition and structure.

Relationship of Coarse Woody Debris to Arthropod Availability for Red-Cockaded Woodpeckers and Other Bark-Foraging Birds on Loblolly Pine Boles

This study determined if short-term removal of coarse woody debris would reduce prey available to red-cockaded woodpeckers (Picoides borealis Vieillot) and other bark-foraging birds at the Savannah River Site in Aiken and Barnwell counties, SC. All coarse woody debris was removed from four 9-ha plots of mature loblolly pine (Pinus taeda L.) in 1997 and again in 1998. We sampled arthropods in coarse woody debris removal and control stands using crawl traps that captured arthropods crawling up tree boles, burlap bands wrapped around trees, and cardboard panels placed on the ground. We captured 27 orders and 172 families of arthropods in crawl traps whereas 20 arthropod orders were observed under burlap bands and cardboard panels. The most abundant insects collected from crawl traps were aphids (Homoptera: Aphididae) and ants (Hymenoptera: Formicidae). The greatest biomass was in the wood cockroaches (Blattaria: Blattellidae), caterpillars (Lepidoptera) in the Family Noctuidae, and adult weevils (Coleoptera: Curculionidae). The most common group observed underneath cardboard panels was Isoptera (termites), and the most common taxon under burlap bands was wood cockroaches. Overall, arthropod abundance and biomass captured in crawl traps was similar in control and removal plots. In contrast, we observed more arthropods under burlap bands (mean ± SE; 3,021.5 ± 348.6, P = 0.03) and cardboard panels (3,537.25 ± 432.4, P = 0.04) in plots with coarse woody debris compared with burlap bands (2325 ± 171.3) and cardboard panels (2439.75 ± 288.9) in plots where coarse woody debris was removed. Regression analyses showed that abundance beneath cardboard panels was positively correlated with abundance beneath burlap bands demonstrating the link between abundance on the ground with that on trees. Our results demonstrate that short-term removal of coarse woody debris from pine forests reduced overall arthropod availability to bark-foraging birds.

In-channel transient storage and associated nutrient retention: Evidence from experimental manipulations

We examined the effect of in-channel flow obstructions such as vegetation and coarse woody debris (CWD) on transient storage and nutrient uptake by using experimental channel manipulations. Transient storage and nutrient uptake were measured under existing conditions in a vegetated agricultural stream and a shaded blackwater stream, and measurements were repeated after removal of vegetation and CWD. Removal of vegetation and CWD decreased transient storage area (As) by 61% and 43% in the agricultural and blackwater streams, respectively, and decreased the portion of median travel time owing to transient storage (Fmed) by 45% and 56%, respectively. Flow baffles were then added to create in-channel transient storage in both streams. Baffles increased As 227% and 119% for the agricultural and blackwater streams, respectively, and increased Fmed 309% and 132%, respectively. Ammonium and PO4 uptake for the blackwater stream, determined by using nutrient addition experiments and expressed as the mass transfer coefficient (Vf), decreased after CWD removal by 88% and 38%, respectively. Ammonium Vf in the blackwater stream increased 143-fold after baffles were installed, and PO4 Vf increased from — 1.7 to 53 mm min−1. Nutrient uptake rates were not calculated for the agricultural stream because sediment disturbance inadvertently altered the sediment-water column nutrient equilibrium. Results from both streams demonstrate that in-channel transient storage, rather than hyporheic storage, can be a substantial portion of overall transient storage in streams. In-channel transient storage influenced nutrient uptake in a blackwater stream, although these results could not be corroborated with data from the agricultural stream.

Soil solution nitrogen concentrations and leaching rates as influenced by organic matter retention on a highly productive Douglas-fir site

Forest harvesting and organic matter management practices may affect the cycling of nutrients, particularly nitrogen (N), through the removal of different organic matter components (e.g. branches, foliage, coarse woody debris) from a site, and the associated changes in carbon-source quantity and quality. This study examined the influence of intensive harvesting and organic matter retention practices on soil N dynamics on a highly productive (site index I–II+) coastal Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) site in southwestern Washington, while controlling for all competing vegetation. The specific focus of this investigation was to determine the effects of bole-only (BO) harvesting and total-tree harvesting plus coarse woody debris removal (TP) on soil solution N concentrations and leaching rates (to a depth of 1.0 m) during the third through fifth years following harvest. Additional comparisons were made between the harvested treatments and adjacent non-harvested portions of the same forest stand (FS). Soil solution monitoring over 3 years indicated that the increased organic matter retention associated with BO harvesting increased the total N concentrations and leaching flux to a depth of 1.0 m by roughly three times relative to TP harvest treatments. Nitrate comprised a majority of the 75, 29 and 4.5 kg ha −1 yr −1 of total N leached in the BO, TP and FS observations, respectively. The cumulative quantity of N leached to a depth of 1.0 m over 3 years was a small percentage (BO = 1.5%, TP = 0.6% and FS < 0.1%) of the 15 mg ha −1 total mineral soil N pool to a similar depth. In the two different organic matter retention treatments, this cumulative N flux was proportional (∼30%) to the amount of N left on site in the form of forest floor and coarse woody debris.

Coarse woody debris and pine litter manipulation effects on movement and microhabitat use of Ambystoma talpoideum in a Pinus taeda stand

We examined effects of coarse woody debris (CWD) and pine litter (PL) manipulations on movement and microhabitat use by mole salamanders ( Ambystoma talpoideum) in the upper Coastal Plain of South Carolina. Individuals were tracked within field enclosures using harmonic radar detection from 3 December 2002 to 1 August 2003. Enclosure study one (ES1) consisted of three treatments: (1) high CWD/high PL; (2) low CWD/low PL; (3) high CWD/low PL. Enclosure study two (ES2) consisted of two treatment types: complete PL removal and unmanipulated control. Activity of A. talpoideum within ES1 high CWD/low PL, low CWD/high PL and high CWD/high PL treatments did not differ. Individuals subject to ES2 PL removal treatments moved during more nights than individuals in control treatments. During night surveys ES2 PL removal treatments moved on a greater percentage of nights, and were active for longer periods of time, than individuals in control treatments. A. talpoideum exposed to low PL treatments may have utilized CWD as a means of compensating for inadequate microclimate conditions provided by reduced pine litter depth. Our results suggest that reduction of CWD and pine litter has little effect on A. talpoideum activity levels. Conversely, complete pine litter removal prompts individual salamanders to move more frequently and for longer periods, thereby potentially being subjected to increased desiccation and predation risk. Within managed pine forests in the southeastern United States, forest management practices that minimize pine litter and CWD removal can help to maintain suitable habitat for amphibian groups such as ambystomatid salamanders.

Demographic responses of shrews to removal of coarse woody debris in a managed pine forest

We trapped shrews at six 9.3 ha plots from which logs ≥10 cm diameter (coarse woody debris; CWD) had been manually removed and six control plots in managed loblolly pine ( Pinus taeda) forests of the southeastern coastal plain, USA. Trapping was conducted seasonally between autumn 1997 and summer 2001. Capture rates of Cryptotis parva were lower at plots from which CWD was removed than at control plots ( P=0.011) and declined at all plots over the study period ( P<0.001). Capture rates of Blarina carolinensis ( P=0.129) and Sorex longirostris ( P=0.432) did not differ between removal and control plots, but declined over the study period ( P<0.001). Age distributions of B. carolinensis differed between removal and control plots ( P=0.048) with a smaller proportion of individuals in young age categories at removal plots. Sensitivity of Cryptotis to the removal of CWD may have been due to its sociality or low population density at the study area. A reduction in the abundance of young B. carolinensis after removal of CWD may reflect reduced reproduction and immigration of older individuals from outside the plot. Effect of removal of CWD on populations of these shrews was relatively weak compared to strong seasonal and multi-year variation in abundance. However, weak treatment effects may have been partly due to low ambient levels of CWD at control plots.

Vole Use of Coarse Woody Debris and Implications for Habitat and Fuel Management

Woody debris is an increasing management focus in forest, representing multiple and sometimes conflicting values. Fuel management may prioritize removal of coarse woody debris (CWD) to minimize wildfire occurrence, intensity, or both. Conversely, management for wildlife habitat or other ecological values often focuses on retention of CWD. We modeled and quantified CWD use by red-backed voles (Clethrionomys gappri), tested whether voles move selectively in portions of forest stands with greater CWD, and correlated stand-level measures of CWD as habitat to fuel loads, providing a basis of comparison for CWD quantitative guidelines. Voles used CWD at a greater rate than expected based on availability and traveled in portions of stands with greater CWD coverage (21-27 trails made by individual voles in each of 5 forest stands). A strong correlation between stand-measure CWD coverage and fuel-load measure (r = +0.96) provides a basis for comparing CWD guidelines. We concluded that current guidelines from different research fields disagree. Only 2 of the 5 stands we sampled fit with guidelines for fuel management and ectomycorrhizae in the northern Rocky Mountains. Coarse woody debris coverage in all of our stands was well below recommendations for small mammals in coastal forests.

Importance of Coarse Woody Debris to Avian Communities in Loblolly Pine Forests

Abstract: To investigate the importance of standing (snags) and down coarse woody debris ( DCWD) to bird communities in loblolly pine ( Pinus taeda) forests, we compared breeding (1997–1999) and nonbreeding (1997–1998, 1998–1999) responses of birds among two coarse woody debris (CWD) removal and control treatments. In each of four blocks, we established four experimental units: (1) DCWD removed, (2) snags and DCWD removed, and (3) and (4) unmodified control plots. We quantified vegetation layers to determine their effects on the experimental outcome. Total breeding bird abundance, abundance of resident species, breeding bird diversity, breeding species richness, and abundance of Great Crested Flycatchers ( Myiarchus crinitus) were reduced by the removal of DCWD and snags. Total woodpecker and Carolina Wren ( Thryothorus ludovicianus) breeding territories were reduced by snag removal. Weak excavating and secondary cavity‐nesting species, Neotropical migrants, and Eastern Towhees ( Pipilio erythrophthalmus) had fewer breeding territories on plots where DCWD was removed. Red‐headed Woodpeckers ( Melanerpes erythrocephalus) and midstory and canopy‐nesting species were at lowest densities on plots where all CWD had been removed. The CWD removal had no effect on the nonbreeding bird community. Most breeding and nonbreeding species used habitats with sparse midstory and well‐developed understory, whereas sparse canopy cover and dense midstory were important to some nonbreeding species. Snag and DCWD retention, and practices that maintain a dense understory and sparse midstory and canopy, will create favorable breeding habitat for many bird species of loblolly pine forests.

Coarse Woody Debris Quantity and Distribution in Central European Streams

Summarized here are ten investigations concerning the volume of coarse woody debris (CWD) in Central European streams. Altogether, 69 stream sections were examined ranging from Northern German lowland streams to brooks in alpine regions. Most of the study streams are according to Central European standards quasi-natural and are bordered by deciduous forest. The geometric mean of CWD volume related to stream length is 1.44 m3 /100 meter reach. Related to stream bottom area, the geometric mean of CWD volume is 0.202 m3 /100 m2 . The mean number of logs (≥10 cm diameter) is 12.5 logs/100 meter reach, and 3.01/100 m2 bottom area (geometric means). Regarding only quasi-natural stream sections (riparian forest currently unmanaged and no removal of CWD for at least 10 years), the geometric mean of CWD standing stock is 0.45 m3 /100 m2 for lowland streams, 0.38 m3/100 m2 for streams in lower mountainous areas and 0.02 m3 /100 m2 for alpine floodplains. From the distribution of size classes and comparison with other studies it is likely, that the current CWD standing stock is considerably less than the potential amount of CWD. For centuries all of the streams have been influenced by man. Historic alterations of the stream, its floodplain and the riparian vegetation may still affect CWD supply and standing stock. We conclude that virtually all streams in Central Europe are highly altered with respect to the amount of CWD, and that the importance of CWD is under-represented in recent assessment principles for streams in Germany.