Pieces Of Coarse Woody Debris Research Articles

Coarse woody debris density and carbon concentration by decay classes in mixed montane wet tropical forests

AbstractThe role of coarse woody debris (CWD) in the global carbon (C) cycle is growing under increasing tree mortality driven by climate variability and disturbances. Quantifying C in CWD critically depends on accurate estimates of CWD density and C concentration in CWD. This study considered the main decomposition pathways (the proportions of CWD decomposed by fungi vs. invertebrates; fungal decay types) and the relationships between decay class, wood density, moisture, and C content of CWD in old‐growth mixed monsoon montane tropical forests in Vietnam based on the inventory of 359 CWD pieces. The bulk density of wood of the 1st, 2nd, 3rd, 4th, and 5th decay classes averaged 0.56, 0.49, 0.37, 0.28, and 0.15 g cm−3, respectively. The density reduction across decay classes did not significantly differ for snags, stumps, branches, leaning, and lying logs. Wood density was negatively related to wood moisture. The wood mass loss averaged 0%, 20%, 37%, 54%, and 74% in the CWD of the 1st, 2nd, 3rd, 4th, and 5th decay classes, respectively. Signs of invertebrate activity were recorded on 3% of CWD pieces. Among CWD samples with identifiable decay type, 88% were decomposed by white‐rot, 8% were decomposed as brown‐rot, and 4% of pieces contained both white‐ and brown‐rot patches. The mean C concentration in wood was 46.5%. It did not change with decay class. Our research provides an empirical basis for future inventories of CWD carbon stocks in Asian montane tropical mixed forests.

Non-negligible role of dead organic matter in a rainforest remnant in Northeast Brazil

Abstract Dead organic matter represents an essential reservoir of carbon, especially that allocated in standing dead trees, coarse woody debris, and fine litter, playing a pivotal role in nutrient cycling and habitat provisioning. However, necromass is frequently disregarded in forest assessments. Here, we aimed to perform the first assessment of multiple necromass compartments in the Atlantic Forest of Northeast Brazil, providing a basis for future integrative studies related to necromass in this region. We registered 17 standing dead trees in 0.5 hectare and 239 logs of coarse woody debris. Necromass had 3.9 Mg.ha-1 of standing dead trees, 54.24 Mg.ha-1 of coarse woody debris and 7.2 Mg.ha-1 of litter. We indicate that standing dead trees and coarse debris were mostly in the intermediate and final stages of decomposition. Leaves were the dominant component of litter, and drier months had more litterfall. Finally, we highlight that assessing standing dead trees and coarse woody debris adds 25.6% on top of aboveground tree mass, improving information about organic matter storage in rainforest ecosystems. Our findings emphasize that the necromass compartment must be considered in forest assessments, also including small pieces of coarse woody debris, which could inform better practices of forest management.

Characterizing the Assemblage of Wood-Decay Fungi in the Forests of Northwest Arkansas.

The study reported herein represents an effort to characterize the wood-decay fungi associated with three study areas representative of the forest ecosystems found in northwest Arkansas. In addition to specimens collected in the field, small pieces of coarse woody debris (usually dead branches) were collected from the three study areas, returned to the laboratory, and placed in plastic incubation chambers to which water was added. Fruiting bodies of fungi appearing in these chambers over a period of several months were collected and processed in the same manner as specimens associated with decaying wood in the field. The internal transcribed spacer (ITS) ribosomal DNA region was sequenced, and these sequences were blasted against the NCBI database. A total of 320 different fungal taxa were recorded, the majority of which could be identified to species. Two hundred thirteen taxa were recorded as field collections, and 68 taxa were recorded from the incubation chambers. Thirty-nine sequences could be recorded only as unidentified taxa. Collectively, the specimens of fungi collected in the forests of northwest Arkansas belong to 64 and 128 families and genera, respectively.

Natural and human-related determinants of dead wood quantity and quality in a managed European lowland temperate forest

Much is known about the minimum thresholds for dead wood that would ensure the persistence of saproxylic organisms and maintain the overall biodiversity of forest ecosystems, but reaching those thresholds is still a challenge in forests where nature conservation is not the sole goal (e.g., Natura 2000 forests managed for timber). Understanding what determines the quantity and quality of dead wood in managed forests is a prerequisite for developing methods to increase its retention without decreasing a forest’s production. We surveyed the volume, number, stage of decay, and species identity of standing and lying coarse woody debris (CWD) in 183 stands in a complex of lowland Natura 2000 forests in southern Poland, and then determined the relationships between these parameters and tree stand structure, intensity of previous silviculture interventions, accessibility of terrain, and local community impact. CWD volume varied from 0.1 to 66.3 m3 ha−1 (average 6.9 m3 ha−1), which is up to several times less than the recommended thresholds. Large-sized CWD and CWD of species known to support rich communities of saproxylic organisms (e.g., Carpinus betulus) were clearly underrepresented. Wood of economically less valuable species was often left in the forest, which boosted the diversity of CWD microhabitats. CWD quantity and quality was significantly shaped by both natural and human-related factors. Among the latter, harvesting intensity and proximity to human settlements affected CWD negatively, while terrain-related difficulties (distance to roads, watercourse density) affected it positively. Surprisingly, the site accessibility effect was important even though the studied area is level and covered by a dense road network. The results suggest that cost-effective CWD management plans for Natura 2000 forests, or, more broadly, multifunctional forests, should discourage some practices accompanying timber harvesting (e.g., fragmenting of pieces of aged CWD), promote practices that positively affect CWD (e.g., not harvesting low-value timber), and set aside small areas to accelerate CWD retention. These things should be done wherever their effects are unlikely to be reversed, i.e., at sites difficult for forestry vehicles to access and away from human settlements.

Proximity to charred logs in burned forests likely affects decomposition processes in the soil

We studied the spatial decomposition rates of standardised organic substrates in soils (burned boreal pine-dominated sub-xeric forests in eastern Finland), with respect to charred and non-charred coarse woody debris (CWD). Decomposition rates of rooibos plant litter inside teabags (C:N = 42.870 ± 1.841) and pressed-sheet Nordic hardwood pulp (consisting of mainly alpha-cellulose) were measured at 0.2 m distance from 20 charred (LC0.2) and 40 non-charred logs (LNC0.2). We also measured decomposition at 60 plots located 3–10 m away from downed logs (L3,10). The rooibos decomposition rate constant ‘k’ was 8.4% greater at the LNC0.2 logs than at the L3,10 or LC0.2 logs. Cellulose decomposed more completely in 1 micron mesh bags at LNC0.2 (44% of buried bags had leftover material) than at LC0.2 (76%) or L3,10 (70%). Decomposition of cellulose material was rapid but varied greatly between sampling plots. Our results indicate that decomposition of the standardised organic matter was more rapid close to CWD pieces than further away. However, only the plots located near non-charred logs (LNC0.2) exhibited high decomposition rates, with no corresponding increase observed at the charred logs (LC0.2). This suggests a possible noteworthy indirect effect of forest burning on soil organic matter (SOM) decomposition rates close to charred CWD after forest fires. We urge for more studies on this tentative observation as it may affect the estimates on how fires affect carbon cycling in forests.

Estimating uncertainty in the volume and carbon storage of downed coarse woody debris.

Downed coarse woody debris, also known as coarse woody detritus or downed dead wood, is challenging to estimate for many reasons, including irregular shapes, multiple stages of decay, and the difficulty of identifying species. In addition, some properties are commonly not measured, such as wood density and carbon concentration. As a result, there have been few previous evaluations of uncertainty in estimates of downed coarse woody debris, which are necessary for analysis and interpretation of the data. To address this shortcoming, we quantified uncertainties in estimates of downed coarse woody debris volume and carbon storage using data collected from permanent forest inventory plots in the northeastern United States by the Forest Inventory and Analysis program of the USDA Forest Service. Quality assurance data collected from blind remeasurement audits were used to quantify error in diameter measurements, hollowness of logs, species identification, and decay class determination. Uncertainty estimates for density, collapse ratio, and carbon concentration were taken from the literature. Estimates of individual sources of uncertainty were combined using Monte Carlo methods. Volume estimates were more reliable than carbon storage, with an average 95% confidence interval of 15.9 m3/ha across the 79 plots evaluated, which was less than the mean of 31.2 m3/ha. Estimates of carbon storage (and mass) were more uncertain, due to poorly constrained estimates of the density of wood. For carbon storage, the average 95% confidence interval was 11.1 Mg C/ha, which was larger than the mean of 4.6 Mg C/ha. Accounting for the collapse of dead wood as it decomposes would improve estimates of both volume and carbon storage. On the other hand, our analyses suggest that consideration of the hollowness of downed coarse woody debris pieces could be eliminated in this region, with little effect. This study demonstrates how uncertainty analysis can be used to quantify confidence in estimates and to help identify where best to allocate resources to improve monitoring designs.

Detection of coarse woody debris using airborne light detection and ranging (LiDAR)

Coarse woody debris (CWD) is an essential component of forest ecosystems that provides habitat for diverse species, functions in water and nutrient cycling, and can be a potential surface fuel in wildfires. CWD detection and mapping would enhance forestry and wildlife research and management but passive remote sensing technologies cannot provide information on features beneath forest canopy, while field-based CWD inventories are not practical for mapping CWD over large areas. Airborne light detecting and ranging (LiDAR) is a remote sensing technology that provides detailed information on three-dimensional vegetation structure that could overcome limitations of passive remote sensing technologies and field-based inventories. Our objectives were to evaluate whether airborne LiDAR could be used to detect individual pieces of CWD. We measured 1679 pieces of CWD at 144 field plots from 2015 to 2016. We acquired high-density (∼24 first returns/m2) LiDAR data in 2014, filtered out canopy and sub-canopy returns using a height threshold based on field measurements of CWD, and used height-filtered data to determine which field-measured pieces of CWD were visible in the resulting point cloud. CWD pieces that were detected constituted 50% of plot CWD volume, and there was a strong, positive correlation between total plot CWD volume and volume of detected pieces (r = 0.96). Overall, we detected 23% of the individual pieces of CWD we measured. Large pieces of CWD were most likely to be detected, with the majority of pieces ≥30 cm diameter or ≥13.9 m long detected. Canopy density, shrub density, and forest type did not influence detection probability. CWD detection rates increased from 1 pulses/m2 to 16 pulses/m2, and CWD detection rate was constant from 16 pulses/m2 to 24 pulses/m2. Our results demonstrate that airborne LiDAR can be used to detect CWD. LiDAR-based detection and mapping of CWD will be most useful for applications that focus on larger and longer pieces of CWD or applications focused on total CWD volume.

Use of constructed coarse woody debris corridors in a clearcut by American martens (Martes americana) and their prey

American martens (Martes americana) are typically associated with mature coniferous forests because they provide overhead cover and coarse woody debris (CWD) that martens require for protection and hunting. Therefore, clearcuts are considered poor marten habitat because they contain no overhead cover and relatively little CWD. We examined the efficacy of retaining CWD and constructing CWD corridors in a recently harvested clearcut to promote the use of the area by martens and small mammals, a major prey resource. We installed remote cameras in corridors, the surrounding clearcut and forest to monitor the distribution of martens and small mammals. Martens and red squirrels did not use CWD corridors more frequently than clearcut areas in summer; forest-floor small mammals, however, used corridors approximately three times as frequently as other habitats (x² = 13.374, P = 0.001). Marten presence was positively associated with mature, dense forest and long pieces of CWD. In winter, red squirrels used corridors more frequently than other clearcut areas, and limited data suggested that martens preferred the corridors to other clearcut areas. Consequently, we recommend that forest managers retain CWD and construct CWD corridors within clearcuts to provide small mammal habitat, and to enhance marten habitat.

Decay of Scots pine coarse woody debris in boreal peatland forests: Mass loss and nutrient dynamics

Although boreal forests have been the setting for numerous studies on the decomposition of coarse woody debris (CWD), these have been limited to mineral soils. In boreal peatland forests, CWD decay rates and nutrient dynamics have not been previously quantified. Therefore, we investigated the decomposition of Scots pine (Pinus sylvestris L.) logs incubated for 10–15 years in three climatically and nutritionally different, managed peatland forests in the European boreal zone. This information is needed for, e.g., estimations of the ecosystem carbon balance. Further, our motivation for studying nutrient dynamics was to evaluate if deliberate retention of large pieces of CWD can make a difference in the nutrient management of the post-harvest stand. We focused on the wood component, which, unlike pine bark, is known to decay slowly, and may thus be important as a long-term nutrient store and source. Changes in wood nutrient concentrations and contents were studied at our primary experimental site (south boreal), which included both control (i.e., forested) and clearcut treatments. Based on mass loss from logs over time, decay rates (k, year−1) decreased with increasing latitude as follows: hemiboreal (0.081), south boreal (0.068), and north boreal (0.062); however, the difference between the latter two was not significant. The hemiboreal site, which had the mildest climate and highest nutrient status, thus accounted for the fastest rate of CWD decay. Generally, smaller logs decayed faster than larger ones. At the south boreal site, the clearcut environment accelerated CWD decomposition (k, 0.085 year−1) compared to that under forest canopy. After fifteen years of decay, logs retained N, and accumulated P to more than double initial amounts at our P-limited site. The loss of carbon typically surpassed the loss of nutrients, even base cations. Nutrient trends were mostly similar with versus without forest canopy, but faster decay in the clearcut consequently expedited these trends (e.g., P accumulated faster). However, at CWD quantities of 5–100 m3 ha−1, the nutrient store in the wood component of CWD was small relative to that in the peat. Hence, CWD retention is apparently not a long-term solution for conserving nutrients in managed pine-dominated peatland forest.

Phylogenetic analysis of Ganoderma australe complex in a Bornean tropical rainforest and implications for mechanism of coexistence of various phylogenetic types

We hypothesized that different phylogenetic types of the Ganoderma australe complex can coexist and that their coexistence is promoted by resource partitioning among them. Our field survey and phylogenetic analysis revealed six phylogenetic types coexisting within a 3 ha primary forest plot in a Bornean tropical rainforest. Two of the six have been reported previously, whereas the remaining four are new. Fruit bodies of all dominant phylogenetic types appeared more frequently from fresh coarse woody debris than expected. Comparison of resource use patterns between the observed fungal community and the null community did not provide significant evidence of niche partitioning. Although we found high genetic diversity within the plot, the phylogenetic types at the site share resources. Resource partitioning on phylogenetic types of host trees or stochastic processes during colonization of pieces of coarse woody debris might play an important role in forming the community structure of phylogenetic types of G. australe.

High stocks of coarse woody debris in a tropical rainforest, East Kalimantan: Coupled impact of forest fires and selective logging

Forest fires coupled with logging have now become one of the most extensive causes of forest degradation, affecting the balance between carbon emissions and sequestration in lowland tropical forests in Southeast Asia. Being transient pools of disturbance-killed trees, coarse woody debris (CWD) stocks play a key role in the carbon budget of such disturbed forests. Here, we investigated for the first time how logging affects the CWD input during and following a fire and, consequently, post-fire CWD stocks. Measurements were made at a permanent site in Bukit Soeharto Education Forest (BSEF) in East Kalimantan, Indonesia. This site consisted of plots that had been subjected to three different logging intensities (HF: heavily felled, trees with diameter at breast height (DBH) ⩾30cm were felled; LF: lightly felled, trees with DBH ⩾50cm were felled; UF: unfelled), all of which were burned by a fire that occurred during a drought associated with the El Niño Southern Oscillation in 1998, shortly after logging. CWD mass were measured in 2012, following 14years of monitoring the CWD inputs. The average CWD mass across the three logging treatments was 89Mgha−1, which is higher than the reported values for undisturbed forests but within the recorded range for recently disturbed forests. The amount of CWD inputs due to tree death during the fire was similar among the three treatments. However, there was a large difference in the CWD input in the post-fire period. In UF plots, large CWD inputs lasted for 2years following the fire due to delayed tree death, whereas in HF and LF plots, where the above-ground biomass had greatly reduced by selective logging, no further large CWD inputs occurred after the fire. Consequently, the CWD stocks in the HF and LF plots were 50–60% lower than those in the UF plots. A simulation predicted that these CWD inputs during and shortly after the fire still constitute a large proportion of the CWD stocks in 2012, suggesting that the CWD pool is a rather durable carbon store in BSEF. In the HF and LF plots, there was few large diameter CWD pieces, reflecting the selective logging of large diameter trees, whereas, in the UF plots, there were large standing dead and uprooted trees. Since the larger diameter CWD pieces are persist in the forest for a longer time continuing to store carbon and to provide habitats for diverse wild life, selective logging could have large impacts on forest ecology and function not only by decreasing the total CWD inputs and stocks but also by decreasing the large diameter CWD pieces.

The decomposition rate of non-stem components of coarse woody debris (CWD) in European boreal forests mainly depends on site moisture and tree species

The decomposition rate of CWD is a key missing link for a quantitative understanding of forest ecosystem functioning. We examined factors influencing decomposition rates of bark, roots and branches from aspen (Populus tremula), birch (Betula pendula, B. pubescens), fir (Abies sibirica), spruce (Picea abies, P. obovata), Scots pine (Pinus sylvestris) and Siberian pine (Pinus sibirica) CWD in three primeval European boreal forests. The chronosequence approach with estimates of single exponential decomposition rate (k) based on calculation of mass loss was used. The k of non-stem parts increased in the order: branches (0.006 year−1 for P. sibirica and 0.020 year−1 for other species), roots in poorly drained sites (0.025 year−1), roots in well-drained sites (0.034 year−1) and bark (0.110 and 0.138 year−1 and 0.147 and 0.255 year−1 under poorly and well-drained conditions and from 1 to 3 m and >3 m above the root collar, respectively). Our results predict that the rate of decomposition of whole CWD pieces in European boreal forests is a function of vegetation zone, site conditions, tree species and size.

Population dynamics of meadow voles (Microtus pennsylvanicus) and long-tailed voles (M. longicaudus) and their relationship to downed wood in early successional forest habitats

Forest habitats after harvesting or wildfire disturbance are usually dominated by early successional vegetation for up to 5–10 years, as well as downed wood or coarse woody debris (CWD). Abundance of Microtus voles is often highest in these sites with sufficient plant cover being crucial for population increases. The role of CWD for voles is less clear. We tested the hypotheses (H) that (H1) abundance and reproduction of meadow vole (Microtus pennsylvanicus) and long-tailed vole (Microtus longicaudus) populations would be higher on sites with greater amounts of downed wood and that (H2) this relationship would be stronger on sites with sparse vegetation cover. There were two study areas: a dry Douglas-fir (Pseudotsuga menziesii)–lodgepole pine (Pinus contorta) forest and a high-elevation Engelmann spruce (Picea engelmannii)–subalpine fir (Abies lasiocarpa) forest in southern British Columbia, Canada. We monitored the responses of meadow voles and long-tailed voles to three levels of downed wood over a 4-year period in replicated clear-cut sites at each area. Amount of downed wood did not positively influence meadow or long-tailed vole population dynamics, and hence, H1 was not supported. Variability in meadow vole numbers and vegetation precluded a test of H2 for this microtine. In dry forests, abundance of meadow voles on clear-cuts was related to the availability of cover and vertical structure provided by herbs and grasses. Vegetation cover was sparse in the high-elevation clear-cuts and long-tailed voles did seem to be positively affected by the number of pieces of CWD, but not by volume, and hence H2 appeared to be partly supported. In high-elevation or otherwise slow-growing areas, and in areas with long-tailed voles, downed wood left after harvest may provide some cover and structure.

Repeated prescribed fires decrease stocks and change attributes of coarse woody debris in a temperate eucalypt forest.

Previous studies have found negligible effects of single prescribed fires on coarse woody debris (CWD), but the cumulative effects of repeated low-intensity prescribed fires are unknown. This represents a knowledge gap for environmental management because repeated prescribed fires are a key tool for mitigating wildfire risk, and because CWD is recognized as critical to forest biodiversity and functioning. We examined the effects of repeated low-intensity prescribed fires on the attributes and stocks of (fallen) CWD in a mixed-species eucalypt forest of temperate Australia. Prescribed fire treatments were a factorial combination of two seasons (Autumn, Spring) and two frequencies (three yearly High, 10 yearly Low), were replicated over five study areas, and involved two to seven low-intensity fires over 27 years. Charring due to prescribed fires variously changed carbon and nitrogen concentrations and C to N ratios of CWD pieces depending on decay class, but did not affect mean wood density. CWD biomass and C and N stocks were significantly less in Fire than Control treatments. Decreases in total CWD C stocks of -8 Mg/ha in Fire treatments were not balanced by minor increases in pyrogenic (char) C (-0.3 Mg/ha). Effects of prescribed fire frequency and season included significantly less C and N stocks in rotten CWD in High than Low frequency treatments, and in the largest CWD pieces in Autumn than Spring treatments. Our study demonstrates that repeated low-intensity prescribed fires have the potential to significantly decrease CWD stocks, in pieces of all sizes and particularly decayed pieces, and to change CWD chemical attributes. CWD is at best a minor stock of pyrogenic C under such fire regimes. These findings suggest a potential trade-off in the management of temperate eucalypt forests between sustained reduction of wildfire risk, and the consequences of decreased CWD C stocks, and of changes in CWD as a habitat and biogeochemical substrate. Nonetheless, negative impacts on CWD of repeated low-intensity prescribed fires could be lessened by fire intervals of 10 rather than three years (to decrease losses of decayed CWD), and fires in moist rather than dry conditions (to conserve large CWD).

Influence of the substrate and ecosystem attributes on the decomposition rates of coarse woody debris in European boreal forests

Narrowing the uncertainties in coarse woody debris (CWD) decomposition rates depending on the ecosystem and substrate attributes can improve our understanding of biodiversity patterns and carbon dynamics in forest ecosystems. We estimated decomposition rates of aboveground CWD, represented by fallen and leaning logs, stumps and snags >8cm in diameter sampled at eight sites in European boreal forests. In total, 3491 CWD pieces were sampled. The chronosequence period covered a range up to 168years. Single exponential decomposition (mass loss) rates (k) averaged 0.066, 0.032, 0.027, and 0.014year−1 for aspen (Populus tremula) and birch (Betula pendula, Betula pubescens), fir (Abies sibirica) and spruce (Picea abies, Picea obovata), Scots pine (Pinus sylvestris) and Siberian pine (Pinus sibirica), respectively. At the regional-scale, the decomposition rate decreased with increasing difference between maximum and minimum temperatures. The CWD decomposition rate was greater on open fertile sites with moderate moisture compared to rates on poor dry or moist sites under closed tree canopies. CWD tree species played the primary role in decomposition at the CWD-piece scale. CWD position and tree mortality mode were rate-controlling mainly for decomposition of fir and spruce CWD. CWD size did not affect decomposition rates. Our results predict CWD decomposition rates as a function of climatic factors, site conditions, tree species, stem position and mode of tree mortality in European boreal forests at the scale of regions, forest stands and individual CWD pieces.

Fine-scale variation in surface fire environment and legume germination in the longleaf pine ecosystem

Fine-scale heterogeneity in fuels influences fire behavior and, in turn, may influence patterns of plant recruitment and regeneration from soil seed banks. In particular, hard-seeded species, such as many members of the plant family Fabaceae, may experience differential germination and mortality rates as a result of heterogeneous fire intensities mediated by variable distribution of fine and coarse fuels. Post-fire germination was examined for nine legume species native to longleaf pine (Pinus palustris) stands of the southeastern United States in response to fuel variation using a paired laboratory and field study. For both studies, fine fuel loads (longleaf pine needles) and coarse fuels (longleaf pine cones) were manipulated. Germination of seven species was assessed for four months in the field following experimental burns of small plots. Germination and mortality were assessed for six species after exposure to experimental laboratory fires. Burning reduced germination compared to unburned controls in both studies. Furthermore, legumes exposed to burning pine cones experienced greater reductions in germination than when exposed to burning pine needles alone. Manipulation of fine fuel loads did not affect germination in either study. Results suggest that small pieces of coarse woody debris are responsible for differential germination following fire, rather than variation in fine fuels. We present a conceptual model of fine-scale fire effects to explain how long-duration smoldering creates localized mortality events that may drive variation in recruitment from the soil seed bank for longleaf pine ecosystems.

A metric decay-classification system for Eucalyptus coarse woody debris from wet eucalypt forests of southern Tasmania, Australia

A method for generating decay-classification systems was developed for coarse woody debris (CWD). This method was used to generate a decay-classification system for wet eucalypt forest CWD, and trialled on over 120 pieces of CWD sampled from post-logging coupes in southern Tasmania. The developed system was easier to implement than systems currently used in Tasmania, with logs being explicitly classified into specific classes without the possibility of character states being split between adjoining classes. The classes were well-balanced and correlated with age and residual density of the wood. Density variance within the classes was at least as good as the currently-used systems (e.g. mean Coefficient of Variation within classes was 21.3% for new and current systems). The method used to develop the system is transferable to other forest types, and has the flexibility to construct decay-classification systems to suit any predetermined number of classes. The system lends itself to the construction of a dichotomous classification key, which creates an explicit categorisation process that is easy to follow and, in time, allows users to memorise the criterion for each class in turn. The developed classification key allows a simple progression when used in the field whereby once a CWD piece has been classified, the user need not continue further through the key.

From Models to Measurements: Comparing Downed Dead Wood Carbon Stock Estimates in the U.S. Forest Inventory

The inventory and monitoring of coarse woody debris (CWD) carbon (C) stocks is an essential component of any comprehensive National Greenhouse Gas Inventory (NGHGI). Due to the expense and difficulty associated with conducting field inventories of CWD pools, CWD C stocks are often modeled as a function of more commonly measured stand attributes such as live tree C density. In order to assess potential benefits of adopting a field-based inventory of CWD C stocks in lieu of the current model-based approach, a national inventory of downed dead wood C across the U.S. was compared to estimates calculated from models associated with the U.S.’s NGHGI and used in the USDA Forest Service, Forest Inventory and Analysis program. The model-based population estimate of C stocks for CWD (i.e., pieces and slash piles) in the conterminous U.S. was 9 percent (145.1 Tg) greater than the field-based estimate. The relatively small absolute difference was driven by contrasting results for each CWD component. The model-based population estimate of C stocks from CWD pieces was 17 percent (230.3 Tg) greater than the field-based estimate, while the model-based estimate of C stocks from CWD slash piles was 27 percent (85.2 Tg) smaller than the field-based estimate. In general, models overestimated the C density per-unit-area from slash piles early in stand development and underestimated the C density from CWD pieces in young stands. This resulted in significant differences in CWD C stocks by region and ownership. The disparity in estimates across spatial scales illustrates the complexity in estimating CWD C in a NGHGI. Based on the results of this study, it is suggested that the U.S. adopt field-based estimates of CWD C stocks as a component of its NGHGI to both reduce the uncertainty within the inventory and improve the sensitivity to potential management and climate change events.

Myxomycetes appearing in moist chamber cultures on samples of bark and wood collected from coarse woody debris

The species associated with coarse woody debris make up the best known ecological assemblage of myxomycetes, but most records are based on fruiting bodies that have formed in the field under natural conditions and not from samples of bark and wood placed in moist chamber cultures. In this study, samples of bark and wood from pieces of coarse woody debris on the forest floor were collected and used to prepare a series moist chamber cultures. All of the 30 cultures prepared with wood and 29 of the 30 (97%) of the cultures prepared with bark were positive for myxomycetes. Thirty-three different species representing 14 genera were recovered, with 21 species (14 genera) recorded for bark and 22 species (11 genera) recorded for wood. These data indicate that any effort to carry out a truly comprehensive survey of the myxomycetes present at a given locality should include examining samples of coarse woody debris with the moist chamber culture technique.

Association between coarse woody debris and small mammals and insectivores in managed forests

Coarse woody debris (CWD) is generally considered dead woody material in various stages of forest decomposition and has been hypothesized to be an important habitat feature for mammals in forests of the Pacific Northwest, USA. Sherman and pitfall trapping were conducted for 2 years on three paired sites with low and high amounts of CWD. Deer mice was the dominant species with a total capture of 605 (45.6%). Four species of insectivores were captured, including Sorex moncicolus, S. trowbridgii, S. vagrans, and Neurotrichus gibbsii. A Poisson regression model was used to test whether 11 CWD variables could predict insectivore captures. The volume of logs and mean decay were important variables for deer mice use of CWD. Mean distance from pieces of CWD to the capture point was significantly related to the total number of captures of trowbridge shrew (Sorex trowbridgii) and all insectivore species. Vagrant shrews (Sorex vagrans) were significantly associated with log volume. Retaining large size CWD should be part of a management plan for ground-dwelling insectivores in forests to secure their biodiversity.