Availability Of Coarse Woody Debris Research Articles

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.

Retention tree characteristics have major influence on the post-harvest tree mortality and availability of coarse woody debris in clear-cut areas

Retention forestry is widely used for reducing the negative biodiversity impacts of forest management. Its effectiveness depends, however, on the post-harvest dynamics of the retention trees, which in turn are likely affected by both tree- and stand-level factors. Understanding the effects of these factors on tree dynamics is thus essential for evaluating the biodiversity effects of retention forestry. We studied the impact of tree-level factors on the mortality and falling patterns of retention trees in pine-dominated boreal forests of eastern Finland. In total, 2738 retention trees were followed individually for 10years after harvest on 12 study sites with an initial retention level of either 10 or 50m3ha−1. Prescribed burning was applied to half of the sites after harvest. Effects of tree species (pine, spruce or deciduous), diameter and location (grouped or scattered trees) on tree mortality and tree fall after death were assessed using survival analysis. During the 10-year survey period, 55% of the trees died and 81% of the dead trees fell down. The risk of mortality decreased with increasing diameter in all tree species on burned sites. On unburned sites, this applied only to pines and deciduous trees whereas for spruce the largest trees had the highest mortality. On all sites, dispersed trees had higher mortality than grouped trees. Pines had a lower risk to fall down after dying than spruces or deciduous trees. We conclude that tree species, diameter and location can be used to predict the post-harvest mortality and falling of retention trees and to select trees that best meet the aims of retention. However, considering the biodiversity effects, the predicted tree dynamics should not be the only basis for tree selection, but the habitat value of the retained trees must be accounted for as well.

Does woodland condition influence the diversity and abundance of small mammal communities?

Loss of mammal species in Australia in the last 200 years has been attributed to many factors including habitat removal and altered fire regimes. Decline in tree condition could contribute further to the ongoing decline of mammals. Eucalyptus wandoo trees are currently undergoing a decline in condition that can result in a loss of canopy and other changes to the habitat. This paper examines the relationships between E. wandoo tree condition, habitat characteristics and small mammal species richness and abundance. Live-capture trapping was conducted at 24 E. wandoo sites at Dryandra State Forest and Wandoo Conservation Park, Western Australia. Condition and microhabitat variables of E. wandoo were recorded for each site. Generalised additive mixed models revealed a range of habitat and tree condition characteristics that influenced small mammal abundance and species richness, including site litter cover, crown dieback, understorey vegetation cover and tree density. The availability of coarse woody debris played a large role in explaining the abundance of Cercartetus concinnus and Antechinus flavipes, along with other microhabitat and tree condition variables, such as tree leaf litter and crown dieback. Epicormic growth, crown density and the distance to the drift fence from E. wandoo trees were the common variables in the best model for the abundance of Sminthopsis griseoventer. The decline in condition of E. wandoo and the subsequent modifications to the microhabitat are correlated with changes in the small mammal community. A better understanding of how the decline of E. wandoo impacts small mammal communities could improve management practices in E. wandoo woodlands.

Effects of fuel reduction treatments on movement and habitat use of American toads in a southern Appalachian hardwood forest

Prescribed fire is a commonly used management technique for maintaining fire-adapted ecosystems, yet empirical data regarding its effects on amphibians are limited and contradictory. Anurans (frogs and toads) may be the amphibian taxa most negatively affected by fire due to their extensive use of the forest floor; however, short-term abundance studies suggest that terrestrial toads (e.g., Anaxyrus [Bufo] americanus) may benefit from fire-based ecosystem management. We used radio-telemetry to examine the effects of prescribed fire on movements, home range characteristics, mortality, and habitat selection of A. americanus in a southern Appalachian upland hardwood forest. We tracked 26 adult A. americanus between 27 January and 30 May 2012. Toads exhibited high non-breeding site fidelity and traveled 993.5m (±265.9m) mean (±SD) route distance between the breeding ponds and the last recorded location within their summer habitat. We found no evidence of direct mortality of A. americanus from a prescribed fire that occurred on 13 February 2012. Forward stepwise discriminant analysis (DA) revealed that the availability of coarse woody debris (CWD) was a significant discriminator between microhabitats used (i.e., location plots) and random plots (Wilk’s lambda=0.9852, F1, 661=9.9414, p=0.002). Forward stepwise DA revealed that burned and unburned location plots were significantly different (Wilk’s lambda=0.2713, F1, 221=593.6863, p<0.001) based on the percent of plot ground cover comprised of charred material (%char). When %char was excluded from the analysis due to its short-term nature, the percent of plot ground cover comprised of deciduous leaves, a cover item commonly used by toads in unburned locations, was the variable with the most discriminatory power (Wilk’s lambda=0.4243, F1, 221=299.8741, p<0.001). Toads maintained greater distances from CWD in the unburned (mean±SD=119.50±109.64cm) than in the burned locations (mean±SD=86.05±104.81cm; χ12=9.7055, p=0.002). Our results indicate that prescribed fire as implemented in this study did not cause direct mortality, nor did it appear to inhibit migratory movements of adult A. americanus. However, fire reduced the diversity and availability of refugia, especially deciduous leaves, though the availability of alternative cover objects (e.g., CWD) in burned treatments allowed toads to inhabit those areas, suggesting the importance of noncombustible or semi-permanent refugia for A. americanus in fire-managed forests.

Introducing Intensively Managed Spruce Plantations in Swedish Forest Landscapes will Impair Biodiversity Decline

Due to pressure to raise forest productivity in Sweden, there are proposals to apply more intensive forestry methods, but they could have potentially large effects on biodiversity. Here we report a compilation and evaluation of the extent and significance of such effects. We evaluated potential effects on biodiversity by introducing intensively fertilized Norway spruce plantations as a management option in Swedish forests with low conservation values on insects, vascular plants, lichens, bryophytes, and red-listed species. Due to a lack of specific studies addressing this question, we based the evaluation on a combination of available and appropriate empiric and anecdotic knowledge; literature data, and expert judgments largely available in species data bases. Our evaluations suggest that such forests will only harbor species that are common and widespread in conventionally managed stands and that species of conservation interest will be lacking, due to the low heterogeneity and light intensity of even-aged monocultures with dense canopies, short rotation times and low availability of coarse woody debris. Effects at the landscape scale are more difficult to evaluate, but will be dependent on the area utilized and the conservation value of sites used. We conclude that negative effects on biodiversity can be reduced if: (1) only land with the lowest conservational value is utilized; (2) plantations are spatially arranged to minimize fragmentation of the landscape; (3) the quality and quantity of key structural elements (e.g., coarse woody debris, old living trees and snags) are maintained at the landscape level; and (4) management intensity is relaxed on other land. For effective implementation of these measures, legislative frameworks and policy instruments need to be adjusted and new models for planning and monitoring need to be developed.

Impacts of Land-use Management on Small Mammals in the Adirondack Park, New York

We examined the response of small-mammal communities to human disturbance along a gradient from wilderness to managed forest to rural residential development in the Adirondack Park of northern New York. Our objectives were to determine if small-mammal community composition and structure differed among sites along a gradient of human impact and to relate changes in small-mammal community composition to habitat changes along the gradient. We sampled small mammals with track tubes on 10 replicates each of old growth, managed forest, and areas of residential development in the central Adirondacks. We estimated differ- ences in species composition, abundance, diversity, evenness, and community structure, and identified habitat variables associated with differences in these mea- sures. We used canonical correspondence analysis (CCA) to examine the relationship between patterns in small-mammal community composition and sampled habitat variables. Some small-mammal species demonstrated a numerical response to increasing human impact on the landscape, with abundance of total small mammals, eastern chipmunk, and Sorex species highest in old growth and declining in managed forests and areas of residential development. Differences among man- agement types were reflected more strongly in total abundance and community structure than through indices of richness and diversity, which did not differ among management types. Canonical correspondence analysis revealed that 32% of the variability in the small-mammal community could be explained by habitat character- istics and that variables describing availability of coarse woody debris, as well as presence of shrubs in the understory, may create conditions favorable to many small- mammal species in these habitats.

Dead trees and protected polypores in unmanaged north-temperate forest stands of Lithuania

The availability of coarse woody debris (CWD) and distribution of dead trees into categories of mortality (dead standing, broken and uprooted) were investigated in north-temperate forests of central Europe (Lithuania). The studied area comprised 188.7 ha and included 18 different stands 40–130 years of age with a variety of tree species (spruce ( Picea abies (L.) Karst.), pine ( Pinus sylvestris L.), alder ( Alnus glutinosa (L.) Gaertn.), birch ( Betula pendula Roth and B. pubescens Ehrh.), aspen ( Populus tremula L.), oak ( Quercus robur L.), forest types ( caricus-sphagnum, vaccinium-myrtillus, oxalis, myrtillus-oxalis, caricus-calamagrostis) and edaphic conditions (peaty, sandy, loamy soils of different moisture). The stands were excluded from wood harvesting for at least 30 years. A total of 11 365 dead trees (over 10 cm in DBH) or 6160.7 m 3 of dead wood was found (60.2 trees/ha and 32.6 m 3/ha). The volume of CWD per hectare was larger in older stands ( r S=0.78, P<0.01). Tree mortality during the last 2 years consisted of 482 trees and 381 m 3, or 1.28 trees/ha×year and 1.01 m 3/ha×year. In 25–33% of cases it was wind-related. Uprooted and broken trees were of larger DBH than dead standing. The distribution into the categories of mortality was strongly dependent on tree species (chi-square test, d.f.=10, P=0). Dead standing dominated in CWD of pine and alder. Broken trees comprised almost a half in CWD of aspen, and about one-third in birch, alder and oak. Uprooting most often occurred in spruce, aspen and birch. Edaphic conditions and stand age had a pronounced impact on distribution into mortality categories for spruce (chi-square test, d.f.=20, P<0.00001) and pine (d.f.=8, P≤0.0003). On peat soil, only a minority of trees of both pine and spruce was uprooted, and standing dead prevailed. In CWD of spruce and pine, the proportions of both dead standing and broken decreased and that of uprooted trees increased on mineral soils of higher moisture and bulk density in older stands. By contrast, uprooting in birch and alder occurred less often on more wet sites, where the proportions of standing snags were higher. A total of 41 species of wood-decomposing polypores were found in the study area. Among those, 10 (24%) were of conservation value.

Influence of Canopy Closure and Shrub Coverage on Travel along Coarse Woody Debris by Eastern Chipmunks (Tamias striatus)

Abstract We investigated relationships between canopy closure, shrub cover and the use of coarse woody debris as a travel path by eastern chipmunks (Tamias striatus) in the north central United States. Fine scale movements of chipmunks were followed with tracking spools and the percentage of each movement path directly along coarse woody debris was recorded. Availability of coarse woody debris was estimated using line intercepts. We predicted that, if chipmunks used coarse woody debris to reduce their risk of predation, movement along coarse woody debris would be greater for animals tracked at sites with open canopies and thick shrub cover. Travel along coarse woody debris was negatively associated with canopy closure and positively associated with the percent of coarse woody debris available at a site and the percentage of shrub cover at a site. Sex and age of eastern chipmunks did not appear to influence the amount of use of coarse woody debris. Our results suggest that coarse woody debris is more impor...

Relationships between terrestrial vertebrate diversity, abundance and availability of coarse woody debris on south-eastern Australian floodplains

Coarse woody debris (fallen wood, CWD) has been largely stripped from both rivers and their floodplains in the southern Murray-Darling basin of south-eastern Australia. Some of our work suggests that as little as 20 t/ha (on average) remains on floodplains where once the figure may have been closer to 90–125 t/ha. Here we examine the consequences of this depletion of a potentially significant habitat-structural element on the terrestrial vertebrates of the floodplain forests. Three major forests were studied: Gunbower Island, Barmah Forest and the Ovens River floodplain (all in northern Victoria, Australia). In each forest, seven graded (by loads of CWD) sites were investigated over 2 years. Our results show that the only native terrestrial mammal (yellow-footed antechinus Antechinus flavipes) occupies sites in significantly higher densities when wood loads exceed 45 t/ha. Ground- and CWD-using birds are more prevalent, and in richer diversity, in the vicinities of accumulations of woody debris. Overall, fallen-wood loads do not appear to relate significantly to avian patterns apart from at the local scale (i.e. near wood accumulations). Neither frogs nor reptiles appear to be influenced by fallen-wood loads. These results suggest that restoration targets might reasonably be set at about 40–50 t/ha, but it seems that birds would be aided by the imposition of a high variance in CWD-load densities rather than an even distribution. Numbers of reptiles are very low, which may reflect the very broad-scale depletion of fallen timber from these habitats; similar impacts may have been expressed in wood-depleted box-ironbark forests immediately to the south of the floodplain forests.

Availability of coarse woody debris in a boreal old‐growth Picea abies forest

Abstract. This study reports temporal (based on cross‐dated dead trees) and spatial patterns of availability of coarse woody debris (CWD) from Picea abies in a Swedish boreal landscape with discrete old‐growth forest patches in a wetland matrix. Data were collected from 29 patches ranging in size from 0.3 to 28 ha. A total of 897 dead trees with a minimum diameter of &gt; 15 cm occurred on the 7.2 ha area analysed. The year of death was established for 50% of these trees.CWD volume ranged from 17 to 65 m3/ha for downed logs and from 0.5 to 13 m3/ha for standing snags. CWD of all decay stages and diameter classes occurred abundantly and the probability of finding logs of all decay stages and sizes was very high at the scale of single hectares. Tree mortality differed among 5 yr periods. However, during the last 50 yr no 5 yr period produced less than 3 logs/ha. Decay rates were highly variable among different logs. Logs with soft wood and some wood pieces lost (decay stage 5) died ca. 34 years ago. This suggests a fairly rapid decay in this northern forest. The data indicate a high and continuous availability of CWD of all types. It is likely, therefore, that selection pressures for efficient dispersal among CWD dependent species may not be very high. Consequently, species with narrow habitat demands and/or low dispersal ability may have evolved and this may contribute to the decrease of certain species in the managed landscape.

New method for welding together ferrous metals by application of heat and pressure : Leonard C. Grimshaw. Metals Technology, Vol. 3, No. 1

Prescribed fire is a commonly used management technique for maintaining fire-adapted ecosystems, yet empirical data regarding its effects on amphibians are limited and contradictory. Anurans (frogs and toads) may be the amphibian taxa most negatively affected by fire due to their extensive use of the forest floor; however, short-term abundance studies suggest that terrestrial toads (e.g., Anaxyrus [Bufo] americanus) may benefit from fire-based ecosystem management. We used radio-telemetry to examine the effects of prescribed fire on movements, home range characteristics, mortality, and habitat selection of A. americanus in a southern Appalachian upland hardwood forest. We tracked 26 adult A. americanus between 27 January and 30 May 2012. Toads exhibited high non-breeding site fidelity and traveled 993.5 m (±265.9 m) mean (±SD) route distance between the breeding ponds and the last recorded location within their summer habitat. We found no evidence of direct mortality of A. americanus from a prescribed fire that occurred on 13 February 2012. Forward stepwise discriminant analysis (DA) revealed that the availability of coarse woody debris (CWD) was a significant discriminator between microhabitats used (i.e., location plots) and random plots (Wilk’s lambda = 0.9852, F1, 661 = 9.9414, p = 0.002). Forward stepwise DA revealed that burned and unburned location plots were significantly different (Wilk’s lambda = 0.2713, F1, 221 = 593.6863, p < 0.001) based on the percent of plot ground cover comprised of charred material (%char). When %char was excluded from the analysis due to its short-term nature, the percent of plot ground cover comprised of deciduous leaves, a cover item commonly used by toads in unburned locations, was the variable with the most discriminatory power (Wilk’s lambda = 0.4243, F1, 221 = 299.8741, p < 0.001). Toads maintained greater distances from CWD in the unburned (mean ± SD = 119.50 ± 109.64 cm) than in the burned locations (mean ± SD = 86.05 ± 104.81 cm; χ12=9.7055, p = 0.002). Our results indicate that prescribed fire as implemented in this study did not cause direct mortality, nor did it appear to inhibit migratory movements of adult A. americanus. However, fire reduced the diversity and availability of refugia, especially deciduous leaves, though the availability of alternative cover objects (e.g., CWD) in burned treatments allowed toads to inhabit those areas, suggesting the importance of noncombustible or semi-permanent refugia for A. americanus in fire-managed forests.