Clear-cut Habitats Research Articles

Forest harvest causes rapid changes of maternal investment strategies in ground beetles.

Species recovery following anthropogenic disturbances will depend on adaptations in survivorship and fecundity. Life-history theory predicts increased environmental stress will result in (1) shifts in resource allocation from fecundity to body growth/maintenance and (2) increased provisioning among offspring at the cost of reproductive output. For remnant populations that persist after forest harvesting, selection mediated through anthropogenic disturbances may affect resilience to additional stressors such as climate change. We tested how rapid changes in environmental conditions affected maternal investment strategies in two ground beetle species, Pterostichus pensylvanicus and Pterostichus coracinus, by comparing fecundity and survivorship in populations from recently clear-cut and uncut habitats. Using parents drawn from clear-cut or uncut stands, we reared progeny in both common garden and reciprocal transplant experiments. In P. pensylvanicus, we found that neither lineage nor rearing habitat affected the number of eggs laid per female or survivorship of offspring. However, eggs laid by females from clear-cuts were more likely to hatch and offspring reached maturity more quickly, suggesting increased provisioning per offspring. In P. coracinus, females from clear-cuts laid more eggs, and their eggs hatched more rapidly and had greater hatching success, suggesting increased investment in overall reproductive output and increased offspring provisioning. In the reciprocal transplant, we observed significant habitat by lineage interactions on survival in P. coracinus, with survivorship increasing when progeny were reared in novel habitats. In both species, increased maternal investment among offspring was not associated with a reduction in overall reproductive output, as anticipated. However, maternal investment among offspring declined with increasing female size, implying trade-offs between increased metabolic demand and fecundity. Taken together, our work suggests that females from more stressful, clear-cut habitats increased investment in fecundity, compared to females from uncut habitats, and may compensate for larval mortality. These changes were driven by smaller individuals, suggesting that increased environmental stress can influence the relationship between female size and maternal investment strategy. Additionally, reciprocal increases in offspring survivorship in habitats other than the parents suggest that adjacent areas between unharvested and clear-cut habitat may be useful in maintaining biodiversity under future climate stressors.

Local habitat association does not inform landscape management of threatened birds

Species that use open patches in forested landscapes often select clearcuts. However, it is unknown whether local associations with clearcuts translate to an effect of clearcut amount in the surrounding landscape on occupancy or abundance at local sites. This question is important because forest management decisions are made at landscape scales. We examined whether the amount of clearcut in the surrounding landscape influenced site occupancy of two threatened aerial insectivores, Common Nighthawk and Eastern Whip-poor-will. Both species nest in/near clearcuts at a local-scale. We used acoustic recorders placed on edges of recent clearcuts (≤ 15 years old, n = 49 sites) to measure presence-absence. We estimated occupancy in relation to the proportion of clearcut and open wetland within the surrounding landscapes at spatial extents between 0.5 and 5.0 km. Occupancy of Eastern Whip-poor-will was not related to clearcut amount in the surrounding landscape at any scale. Common Nighthawk occupancy was lower in sites surrounded by landscapes with higher proportion of older (11–15 years old) clearcuts. Both species’ occupancy was higher in sites where the surrounding landscapes had higher proportions of open wetland. Two possible mechanisms for our results include multi-scale selection of breeding sites or demographic responses to higher productivity in wetlands than clearcuts; both need further study. Our results show how the association of species with clearcut habitats at a local scale does not necessarily translate to a higher occurrence of those species at the landscape scale at which management decisions are made.

Delivery rates and prey use of Mountain Bluebirds in grassland and clear-cut habitats

Delivery rates and prey use of Mountain Bluebirds in grassland and clear-cut habitats

Warming alters the energetic structure and function but not resilience of soil food webs.

Climate warming is predicted to alter the structure, stability, and functioning of food webs1–5. Yet, despite the importance of soil food webs for energy and nutrient turnover in terrestrial ecosystems, warming effects on these food webs—particularly in combination with other global change drivers—are largely unknown. Here, we present results from two complementary field experiments testing the interactive effects of warming with forest canopy disturbance and drought on energy fluxes in boreal-temperate ecotonal forest soil food webs. The first experiment applied a simultaneous above- and belowground warming treatment (ambient, +1.7°C, +3.4°C) to closed canopy and recently clear-cut forest, simulating common forest disturbance6. The second experiment crossed warming with a summer drought treatment (-40% rainfall) in the clear-cut habitats. We show that warming reduces energy fluxes to microbes, while forest canopy disturbance and drought facilitates warming-induced increases in energy flux to higher trophic levels and exacerbates reductions in energy flux to microbes, respectively. Contrary to expectations, we find no change in whole-network resilience to perturbations, but significant losses of ecosystem functioning. Warming thus interacts with forest disturbance and drought, shaping the energetic structure of soil food webs and threatening the provisioning of multiple ecosystem functions in boreal-temperate ecotonal forests.

Arthropods and novel bird habitats: do clear-cuts in spruce plantations provide similar food resources for insectivorous birds compared with farmland habitats?

Arthropods, and insects in particular, constitute important food resources for several higher trophic levels like birds. Their abundance and diversity is likely to differ between habitat types depending on the local conditions and resources. This may have important consequences for arthropod consumers that occupy structurally different habitat types. Most bird-focused studies address, however, habitats at the structural, vegetation-based level and disregard the presence of sufficient quantities and qualities of arthropod prey items. Here, we compare the quantity and quality of ground-dwelling and above-ground arthropods as food resources for early-successional birds between two structurally different human-modified habitat types sharing similar bird assemblages: low-intensity farmland areas and plantation forest clear-cut areas in the south of Belgium. Forest clear-cut patches constitute a novel habitat for so-called ‘farmland’ birds. Our results show that arthropod abundance is substantially higher in farmland than in forest clear-cuts, although arthropods are slightly larger in clear-cuts. Higher arthropod abundance is associated with higher ground-level temperature in farmland. Although both habitat types host the same spectrum of arthropod species, forest and farmland management practices induce different conditions for food quantity and, to some extent, food quality for insectivorous birds. We discuss the mechanisms behind the observed pattern of arthropod abundance and the fitness-related consequences of contrasting food availability in farmland and forest clear-cut habitats for early-successional bird species.

Effects of fine-scale forest habitat quality on movement and settling decisions in juvenile pond-breeding salamanders.

A better understanding of how individuals respond to variation in habitat quality while moving through heterogeneous habitats is needed to predict ecological phenomena at larger scales, such as local population and metapopulation dynamics. We sought to identify how fine-scale habitat quality affects the decisions of juvenile pond-breeding salamanders (Ambystoma maculatum and A. annulatum) to cease dispersive movements away from their natal pond, select a refuge, and settle. Because of the acute susceptibility of juvenile amphibians to evaporative water loss in terrestrial habitats, we predicted that they possess mechanisms for adjusting their behavior in response to variations in fine-scale habitat quality. We used experimental field enclosures to isolate the effects of habitat quality on settling behavior and employed generalized linear mixed models to examine how manipulations in canopy cover (closed or open) and microhabitat (control, compacted soils, high coarse woody debris, high burrow density), along with environmental variables (rainfall and air temperature), affect the individual's probability of settling. Our results indicated that A. maculatum and A. annulatum had a 10% and 30% decreased probability of settling in open-canopy clearcut habitat, respectively, compared to closed-canopy forest habitat. In addition, A. annulatum were 24% less likely to settle in compacted soil treatments. Although the settlement probability of A. annulatum did not depend on refuge availability, A. maculatum were 18% and 25% more likely to settle under conditions of high burrow density and high coarse woody debris, respectively. These findings make a unique contribution to our understanding of amphibian movement ecology by demonstrating how the interplay of external factors and individual behavior produce observed patterns of movement and habitat selection.

Wildfire and Postfire Restoration Action Effects on Microclimate and Seedling Pine Tree Survivorship

AbstractThrough modification of structural characteristics, ecological processes such as fire can affect microhabitat parameters, which in turn can influence community composition dynamics. The prevalence of high-severity forest fires is increasing in the southern and western United States, creating the necessity to better understand effects of high-severity fire, and subsequent postfire management actions, on forest ecosystems. In this study we used a recent high-severity wildfire in the Lost Pines ecoregion of Texas to assess effects of the wildfire and postfire clearcutting on six microclimate parameters: air temperature, absolute humidity, mean wind speed, maximum wind speed, soil temperature, and soil moisture. We also assessed differences between burned areas and burned and subsequently clearcut areas for short-term survivorship of loblolly pine Pinus taeda seedling trees. We found that during the summer months approximately 2 y after the wildfire, mean and maximum wind speed differed between unburned and burned areas, as well as burned and burned and subsequently clearcut areas. Our results indicated air temperature, absolute humidity, soil temperature, and soil moisture did not differ between unburned and burned areas, or burned and burned and subsequently clearcut areas, during the study period. We found that short-term survivorship of loblolly pine seedling trees was influenced primarily by soil type, but was also lower in clearcut habitat compared with habitat containing dead standing trees. Ultimately, however, the outcome of the reforestation initiative will likely depend primarily on whether or not the trees can survive drought conditions in the future, and this study indicates there is flexibility in postfire management options prior to reseeding. Further, concerns about negative wildfire effects on microclimate parameters important to the endangered Houston toad Bufo (Anaxyrus) houstonensis were not supported in this study.

Habitat selection by cattle in Foothill landscapes following variable harvest of aspen forest

Logging of aspen (Populus tremuloides Michx.) forests on public grazing land in west central Alberta creates a mosaic of habitat types that may alter cattle (Bos taurus) use of these landscapes. We used an extensive network of field plots and global positioning system (GPS) collars deployed on cattle within four experimental pastures, each containing a mix of uncut forest, clear cut forest, partially harvested areas, and in-block haul roads, to examine habitat preferences during mid-summer grazing in 2008 and 2009. We also examined the effect of two cattle stocking rates the first year. Although cattle removed similar amounts of forage in all habitats, GPS data indicated cattle spent more time in uncut forests, and avoided clear cuts and in-block haul roads during both years, patterns that remained consistent under either livestock stocking rate tested. Observed patterns of habitat use were attributed to conservative cattle stocking rates consistent with or greater than those allocated on publicly grazed forest land in Alberta, combined with specific habitat attributes. Preferred use of uncut forest was attributed in part to favorable forage quality, which was positively associated with cattle utilization (standardized β=+0.13) among plots. Although forage use by cattle of plots also increased with forage biomass (β=+0.33), sharp increases in biomass following clear cut logging appeared to be offset by reductions in forage use associated with increased slash cover (β=−0.12) and sapling density (β=−0.11), both of which may have impeded cattle access. As a result, forage removal remained similar among habitats. Finally, cattle use of forage decreased with increasing distance from water (β=−0.22), highlighting the importance of ensuring reliable access to water across forested pastures to prevent localized overuse. Overall, the reduced time cattle spent in clear cut habitats coupled with similar forage removal suggests that under low cattle stocking rates, grazing can be compatible with deciduous forest management in the region.

The effects of clearcuts and forest buffer size on post-breeding emigration of adult wood frogs ( Lithobates sylvaticus)

The establishment of terrestrial buffer zones around vernal pools has been recommended to provide upland habitat for pool-breeding amphibians in areas where forestry practices occur adjacent to breeding sites. However, few studies have empirically tested the effectiveness of buffers. We assessed post-breeding emigration behavior (net emigration distance, rate of movement, proportionate use of available habitats) of radio-tagged adult wood frogs ( Lithobates sylvaticus) at nine vernal pools with experimental forest buffer treatments in central Maine, USA. Buffer treatments were either 30-m ( N = 3) or 100-m ( N = 3) forest buffers surrounded by a 100-m wide clearcut; pools surrounded by uncut forest served as reference sites ( N = 3). We tracked 33 individuals in 2004 and 2005, for an average of 41 days, as they emigrated from breeding pools. Recently clearcut habitat was permeable to emigrating adult wood frogs, particularly females. A higher proportion of frogs at 30-m buffer sites than at 100-m buffer sites traveled through the clearcuts to reach intact forest beyond, suggesting that 30-m buffers may not provide sufficient upland habitat to support adult wood frog populations. There was high variability in emigration behavior among frogs, regardless of buffer treatment, and males and females tended to exhibit differential responses to different buffer sizes and to clearcut habitat. Although wood frogs in this study utilized both 30-m and 100-m forest buffers, variability between sexes and density-dependent effects could render small buffers (e.g., 30 m or less) inadequate to support these populations.

Butterfly community recovery in degraded rainforest habitats in the Upper Guinean Forest Zone (Kakum forest, Ghana)

Successful regeneration of secondary tropical forest might be crucial in the conservation of rainforests, since large areas of primary forest have been destroyed or degraded. Animal communities might play an important role in restoration of biological diversity in these secondary habitats, since some groups have high mobility and capacity for dispersal. Fruit-feeding butterflies were trapped to measure differences between butterfly communities in primary rainforest and disturbed forest habitats of different stage of regeneration including clear-cut, abandoned farmland, newly planted forest and middle-aged secondary growth. 3465 specimens representing 114 species were identified from 56 traps operated for 36 days. Extremely high values of rarefied species richness were estimated in the clear-cut habitat, due to the high number of singletons and doubletons. This was caused by a gap-effect that allowed penetration of canopy and open area species after disturbance. The differences between butterfly communities were best demonstrated through ecological composition, richness and abundance of indicator groups and habitat similarity based on Jaccard’s similarity index. The results show a clear ability of butterfly communities in degraded forest habitats to regenerate in 50–60 years after clearance.

Diet and food availability: implications for foraging and dispersal of Prince of Wales northern flying squirrels across managed landscapes

Where dispersal is energetically expensive, feeding and food availability can influence dispersal success. The endemic Prince of Wales northern flying squirrel (Glaucomys sabrinus griseifrons) inhabits a landscape mosaic of old-growth, 2nd-growth, and clear-cut stands, with the latter 2 representing energetically expensive habitats. We estimated the diet of flying squirrels using stable isotope and fecal analyses, determined whether food availability varies among forest stands, and assessed the likelihood of foraging across a managed landscape given the distribution of foods on Prince of Wales Island (POW), Alaska. Both stable isotope and fecal analyses revealed that conifer seeds, lichens, and fungi were the main dietary items consumed and assimilated by flying squirrels. Similarly, soil macroinvertebrates were consumed by squirrels, whereas berries were not. Nonetheless, although examination of stable isotope data suggested that squirrels assimilated few nutrients from truffles, this food source was among the most frequent diet items in feces, probably because flying squirrels assimilate elements other than nitrogen from fungi. Our surveys showed that conifer seeds, truffles, and lichens were more prevalent in old-growth than 2nd-growth and clear-cut habitats. Thus, our results indicate that diet and availability of food items on POW may influence foraging success and dispersal movements of G. sabrinus across fragmented landscapes because of limited availability of food resources in the managed habitats. DOI: 10.1644/09-MAMM-A-014R.1.

An experimental assessment of buffer width: Implications for salamander migratory behavior

Upland buffer zones are the primary proposed management tool for vernal-pool-breeding amphibians; however, experimental validation of the utility of buffers is lacking. We used clear cutting to experimentally manipulate upland buffer widths at 11 vernal pools in east-central Maine. Each pool was randomly assigned to one of three possible treatments: >1000-m buffer, 100-m buffer, or 30-m buffer. We radiotracked 40 adult spotted salamanders at these pools and modeled their migratory behavior with mixed-effects regression. Mean maximum distance salamanders moved from their breeding pool was 106.0 ± 15.4 m (range = 1.6–427.6 m). Salamanders were able to enter and cross clear cuts. We observed differences in migratory behavior between the 100-m buffer and reference treatments and between forest and clear-cut habitat; however, weather conditions and a salamander’s distance from the vernal pool strongly mediated the impact of buffer treatment on migration behavior. Our findings indicate that clear cuts are semi-permeable to adult spotted salamanders, but that degree of permeability and the effects of buffer treatment largely depend on weather conditions.

Experimental trials of the northern flying squirrel (Glaucomys sabrinus) traversing managed rainforest landscapes: perceptual range and fine-scale movements

Successful dispersal in many species may be a function of the distance at which animals can perceive a particular landscape feature (i.e., perceptual range), as well as energetic costs associated with traversing the distance towards that feature. We used a model, relating perceptual range to body size of mammals, to predict the perceptual range of the northern flying squirrel ( Glaucomys sabrinus (Shaw, 1801)) in fragmented forests of Southeast Alaska. We hypothesized that the perceptual range of flying squirrels would be 325.5–356.5 m in clearcuts and 159.7–174.9 m in second-growth stands. The distance advantage in clearcuts may, however, be lost if the cost of transport in that habitat is higher. Our results suggest that as heuristically predicted by the model, the perceptual range of flying squirrels was greater in clearcut habitats than in second-growth stands. Nonetheless, for both habitats the actual perceptual range was significantly shorter than predicted by the model. We found that precipitation, and associated cloud cover and illumination, and wind speed, which affect olfaction capabilities, influenced orientation success. Although squirrels more often oriented towards the forest edge in clearcuts, they paused more often during their movements, which may lead to higher costs of dispersing through this habitat. The application of the mass-based model to nonagricultural landscapes should be done with caution, and variables such as wind and illumination be measured concurrently. Our data illustrate that dispersing squirrels likely will not venture into managed habitats because logging creates clearcuts larger than the perceptual range of these mammals.

Frugivory and seed dispersal by a small carnivore, the Chinese ferret-badger, Melogale moschata, in a fragmented subtropical forest of central China

The capacity for the Chinese ferret-badger ( Melogale moschata), a small carnivorous mustelid mammal, as a frugivore and endozoochorous seed disperser was evaluated over the main fruiting period during 2 years of study in a fragmented subtropical forest of central China. Seeds of eight plant species were dispersed by M. moschata, based on the analysis of the 163 faecal samples. Three forest types were sampled; one subject to commercial clear-cut logging, the second a selectively logged site and the third a natural primary forest habitat. The proportion of seed-bearing faecal samples was greatest amongst those collected from the primary forest, with the selectively logged and clear-cut habitats having a lower frequency of seed-bearing faeces, respectively. Ferret-badgers mainly defecated in open habitats, however the proportion of seed-bearing faeces did not differ according to the type of cover present at the deposition sites. Ferret-badgers selected fleshy-fruited and seed-pulp rich species. Significantly, selection was found for the large-seeded species, Diospyros lotus, however, they chose to consume the smaller seeds from this plant. Seed passage time through the gut ranged between 0.8 and 5.9 h. No significant individual-specific differences were detected in the passage time for the different fleshy fruits. Five out of six dominant species had seeds germinate successfully from faecal samples. Only the germination of D. lotus seeds were lower than expected by comparison to the control seeds. By contrast, ingested seeds of Hovenia dulcis had higher germination rates than in control samples, but no statistical differences were detected. These findings indicated that ferret-badgers were legitimate (they defecated viable seeds), but inefficient dispersers (seeds in faeces were mainly deposited on open sites which were regarded as “unsafe microsites” for seed germination and seedling establishment). In order to fully understand the role of M. moschata in forest recruitment and regeneration, quantitative research on their efficiency as endozoochorous seed dispersers and the effects of their digging activities on the seed bank and seedling survival should be undertaken, focusing on sites degraded by forestry operations, especially in badly affected sites.

Assessing quality of clearcut habitats for amphibians: Effects on abundances versus vital rates in the southern toad ( Bufo terrestris)

Forest clearcutting is a form of habitat alteration that drastically alters the landscape and may contribute to declines in amphibian populations. Indeed, many studies have documented decreases in amphibian abundances and species richness in clearcuts. The development of effective conservation strategies to reduce the effects of timber harvesting has been hindered by lack of knowledge of the mechanisms underlying these changes in abundance. To better understand the potentially negative consequences of forest clearcutting, we used field enclosures in forested and clearcut habitats to examine changes in the survival and growth of juvenile southern toads ( Bufo terrestris) over a two-month period. We also conducted a comparative monitoring study using drift fences and pitfall traps in forests and clearcuts to determine the effect of clearcutting on the abundance of juvenile southern toads. We found no significant effect of habitat on the number of juvenile southern toads captured in forests or clearcuts. In contrast, the average survival of toads in clearcut enclosures was significantly reduced compared to that of toads in forested enclosures (17 ± 5% versus 61 ± 3%). Toads surviving in clearcuts were also significantly smaller than those surviving in forested enclosures (27.9 ± 0.1 mm versus 30.3 ± 0.8 mm SVL). Our results highlight the difficulty in interpreting abundance patterns as a sole metric for habitat comparison. Because there is much interest in studying the effects of habitat alteration on amphibian populations, we recommend that future studies place more emphasis on determining changes in vital rates of populations following habitat alteration.

The effect of femel- and small scale clear-cutting on ground dwelling spider communities in a Norway spruce forest in Southern Germany

The early effects of femel-cutting (removing 20% of the trees) and small scale clear-cutting on ground-living spiders in a Norway spruce (Picea abies (L.) Karst.) forest in Southern Germany were investigated. The study was carried out as BACIP (before and after, control-impact, many paired samplings) study: Spiders were sampled during the pre-treatment year, the year of cutting, and the year after cutting. In total 7101 individuals were sampled, of which 4530 individuals were identified, 4468 were adult and 2633 individuals were juvenile. We identified 107 species, but a single species, Coelotes terrestris, dominated the control (spruce stand) comprising up to 49% of the total identified individuals. Clear-cutting changed the species composition in the traps, while the first step in femel-cutting preserved it. The number of individuals of the families Linyphiidae, Amaurobiidae, Agelenidae and Clubionidae decreased drastically within the 2 years after the clear-cutting, while the Lycosidae became numerically dominant in the clear-cut stands. The number of individuals with the following characterisation decreased significantly after clear-cutting: Small ( 10.5 mm), web builders, ‘forest habitat species’, species favouring hygrophilic to medium moisture conditions, and preferences to live below ground or in and on the moss layer. On the other hand, middle-sized spiders, free hunters, ‘open habitat species’, spiders favouring dry conditions or that are euryoecious, preferring patterns covered by grasses or uncovered patches, increased in number. Clear-cut habitats with dense spruce regeneration showed a delayed and less pronounced response. With femel-cutting, species composition of ground-living spider communities may be preserved during the first step of regeneration of mature forest stands.

Population genetic structure of tailed frogs (Ascaphus truei) in clearcut and old-growth stream habitats in south coastal British Columbia

Ascaphus truei Stejneger, 1899 relies on cool, fast-flowing, forested mountain streams, which receive little protection from logging activities. During recovery of post-logging habitats, local extirpation of Ascaphus is a concern because their recolonization may be slow. In British Columbia, Oregon, and California, coastal Ascaphus populations are designated as "at risk". To infer fragmentation impacts from patterns of genetic structure, we used RAPD molecular markers and compared population genetic structures of Ascaphus larvae in an old growth with an adjacent clearcut stream located in coastal British Columbia. In the clearcut, larvae were less genetically diverse than in the old growth and exhibited no relationship between physical distance and genetic relatedness, whereas in the old growth, genetic similarity decreased with physical distance. Patterns of gene flow between the clearcut and old-growth streams were significantly different. The clearcut population went through a bottleneck/founding event, but also exhibited greater dispersal. The frogs were perhaps searching for new habitat (which would lower isolation by distance) and suffering mortality (which would decrease diversity). Most problems in conservation will require genetic and ecological data, and future research should aim to incorporate methodologies from both fields.

Movements of female white-tailed deer ( Odocoileus virginianus) in relation to timber harvests in the central Appalachians

Deer movements in relation to timber harvests have not been studied within nonmigratory white-tailed deer ( Odocoileus virginianus) populations. We compared home range and core area size and overlap, deer movements during timber harvests, and habitat use before and after harvests for deer associated and not associated with clearcuts. We radio-monitored 83 adult female deer pre- (3 months prior to), during, and post- (3 months after) timber harvest. Change in home range and core area size and overlap did not differ between control deer (home ranges comprised entirely of mature forest during all time periods) and treatment deer (≥1 telemetry location within a harvested stand during any time period). During timber harvests, treatment deer were located outside their pre-harvest home ranges more often than control deer and generally were located closer to clearcuts than in other time periods. During both the pre- and post-timber harvest time periods, deer used clearcut habitats (stands ≤5-years-old) in greater proportion than availability. Lack of significant changes in white-tailed deer movements before, during, and after timber harvest suggests habitat management aimed at attracting deer away from problem areas (e.g., areas with low regeneration success) or toward browse supplies during severe winters would likely be unsuccessful in the central Appalachians of West Virginia.

Influence of habitat and microhabitat on epigeal spider (Araneae) assemblages in four stand types

Studies based on presence=absence of a species may provide insight into habitat associations, allowing the distribution of species to be predicted across the landscape. Our objective was to characterise the epigeal spider fauna in three mature boreal forest types (conifer, mixedwood and deciduous) and a disturbed habitat (clearcut) to provide baseline data on the spider species inhabiting major forest types of boreal northwestern Ontario, Canada. Only spring-active epigeal spiders were considered for logistical reasons. We further identified the coarse woody debris structure and microhabitat characteristics within these stand types to try to refine our ability to predict the within-stand occurrence of spiders. We found the clearcut habitat strongly dominated by the Lycosidae with 55% of spiders represented by a single species, Pardosa moesta Banks. The forested habitats were more diverse, with web-building families forming a large component of the fauna and many species represented by only a few individuals. The spider com- position of the deciduous stands (aspen and mixedwood) was very similar, and distinct from that of spruce stands. Species such as Agroeca ornata (Emerton) (Liocranidae) and Pirata montanus Emerton (Lyco- sidae) were strongly associated with deciduous leaf litter. Within the spruce stands, Agyneta olivacea (Emerton) (Linyphiidae) and Pardosa uintana Gertsch (Lycosidae) were associated with feathermoss rather than Sphagnum microhabitats. Many of the habitat associations observed at Rinker Lake do not conform well to those described in the taxonomic literature as typical for the species. Few associations with coarse woody debris or microhabitat attributes (other than ground cover type) were found.

Influence of habitat and microhabitat on carabid (Coleoptera: Carabidae) assemblages in four stand types

AbstractStudies based on presence/absence of a species may provide insight into habitat associations, allowing the distribution of species to be predicted across the landscape. Our objective was to characterize the carabid fauna in three mature boreal forest types (conifer, mixedwood, and deciduous) and a disturbed habitat (clearcut) to provide baseline data on the carabid species inhabiting the major forest types of boreal northwestern Ontario. Only spring-active carabids were considered for logistical reasons. We further identified the coarse woody debris structure and microhabitat characteristics within these stand types to try to refine our ability to predict the within-stand occurrence of carabids. We found the carabid composition of deciduous stands (mixedwood and aspen) similar and typical of the carabid fauna found in mixedwood forest in other nearby studies. The important feature of these forest types may be the presence of a deciduous leaf litter layer. In contrast, spruce stands contained fewer species and individuals and a distinct carabid fauna. As predicted, the clearcut habitats were dominated by open habitat species, although the fauna was dissimilar to what was recorded in clearcut habitats in other studies within northwestern Ontario. Coarse woody debris appeared to be an important habitat attribute for several carabid species in clearcut habitats.