Effects Of Timber Harvesting Research Articles

Short-Term Forest Management Effects on a Long-Lived Ectotherm

Timber harvesting has been shown to have both positive and negative effects on forest dwelling species. We examined the immediate effects of timber harvests (clearcuts and group selection openings) on ectotherm behavior, using the eastern box turtle as a model. We monitored the movement and thermal ecology of 50 adult box turtles using radiotelemetry from May–October for two years prior to, and two years following scheduled timber harvests in the Central Hardwoods Region of the U.S. Annual home ranges (7.45 ha, 100% MCP) did not differ in any year or in response to timber harvests, but were 33% larger than previous estimates (range 0.47–187.67 ha). Distance of daily movements decreased post-harvest (from 22 m±1.2 m to 15 m±0.9 m) whereas thermal optima increased (from 23±1°C to 25±1°C). Microclimatic conditions varied by habitat type, but monthly average temperatures were warmer in harvested areas by as much as 13°C. Animals that used harvest openings were exposed to extreme monthly average temperatures (∼40°C). As a result, the animals made shorter and more frequent movements in and out of the harvest areas while maintaining 9% higher body temperatures. This experimental design coupled with radiotelemetry and behavioral observation of a wild ectotherm population prior to and in response to anthropogenic habitat alteration is the first of its kind. Our results indicate that even in a relatively contiguous forested landscape with small-scale timber harvests, there are local effects on the thermal ecology of ectotherms. Ultimately, the results of this research can benefit the conservation and management of temperature-dependent species by informing effects of timber management across landscapes amid changing climates.

Meta-analysis of the effects of canopy removal on terrestrial salamander populations in North America

Terrestrial salamander abundance in North American forests is closely associated with forest characteristics, and salamander populations typically decline following timber removal. However, salamander responses to timber harvest vary considerably from one study to the next – some studies have shown limited or no effects whereas others have found harvest-related declines of up to 95%. To estimate overall effect sizes of timber harvest on salamander populations and to examine factors that contribute to variation in salamander responses to harvest, we carried out a meta-analysis of published studies of the effects of timber harvesting on terrestrial salamander abundance. Based on 108 salamander species/treatment combinations from 24 studies, we found mean harvest-related declines ranged from 29% (95% CI=−2% to 51%) for long-term responses to partial canopy removal to 62% (95% CI=29% to 80%) for short-term responses to clearcutting. Multivariate mixed models suggested that clearcutting had a modestly greater impact on salamander populations than partial harvest and that decreases following harvest were more pronounced at sites with warmer summer high temperatures. In addition, active sampling of salamanders (e.g., surface counts) led to greater apparent effects of timber harvest than passive sampling (e.g., cover boards or pitfall traps), suggesting that sampling methodology influenced the perceived effects of harvest. In the studies evaluated, salamander numbers almost always declined following timber removal, but salamanders were never extirpated and populations typically increased as forests regenerated.

Temporal changes in the relative abundance of amphibians relative to riparian buffer width in western Washington, USA

In certain regions of Canada and the United States, amphibians have been shown to be sensitive to forest management and the short-term adverse effects of timber harvesting on terrestrial amphibians have been well documented in the literature. However, the effects of silvicultural treatments on amphibians may not be realized until many years after treatment. Manipulative forest management experiments with pre- and post-treatment data, random assignment of replicates to treatments, and analyses over a large spatial scale are rare in the literature. Furthermore, even studies with pre- and post-treatment data can be affected by ecological time lags; the longevity of some species may mean that it could take several years to observe a treatment effect. Riparian areas in forested landscapes of the Pacific Northwest have been recognized for high species richness of amphibians yet little is known about the persistence of amphibians in mature forest fragments such as unharvested riparian buffers surrounded by clearcuts. Our study investigated the efficacy, 2 and 10 years post-logging, of two different riparian management zone prescriptions established around third- and fourth-order streams in western Washington to mitigate the effects of upland timber harvest on amphibians. Our findings suggest that there is no global response by terrestrial amphibians to logging or to the retention of riparian management zones. Rather, species showed individual responses that varied over time and between treatments and transects. Specifically Coastal Tailed Frogs (Ascaphus truei) declined in clearcut upland habitats 2- and 10-years following logging while Western Red-backed Salamander (Plethodon vehiculum) and Ensatina (Ensatina eschscholtzii) appear to benefit from the recommended riparian management zone width. The influence of site effects was evident for some species, whereas for others there is some suggestion of treatment effects, but the analyses were confounded by patterns of natural population change at both local and regional scales, which were evident 2 years following logging. Our results exemplify the need for longer-term studies to ensure that potentially confounding factors, such as natural population fluctuation, are considered when interpreting the results of time series data.

Effects of Timber Harvesting on Dissolved Oxygen in a Northern Louisiana Headwater Stream

Effects of Timber Harvesting on Dissolved Oxygen in a Northern Louisiana Headwater Stream

Does timber harvest influence the dynamics of marine-derived nutrients in Southeast Alaska streams?

Streams often rely on nutrient subsidies, and variation in nutrient delivery may alter the ecosystem response. Pacific salmon (Oncorhynchus spp.) provide marine-derived nutrients to their natal streams but also cause benthic disturbance, with the net effect determined by watershed and stream characteristics. To understand the factors contributing to variation in salmon-derived nutrients (SDN), we studied nutrient concentration and export in seven streams with varying physical characteristics due to timber harvest (e.g., channel complexity) over three years in Southeast Alaska, USA. Salmon increased concentrations and export of dissolved and particulate nitrogen, phosphorus, and carbon, but the magnitude of increase varied up to 41-fold among streams. The density of live salmon best predicted the increase in nutrient concentration and export, whereas the density of carcasses had a negligible effect. Nutrient export was predicted by transient storage before and after the salmon run. Streams in harvested watersheds with simplified channels had greater nutrient export than those in pristine watersheds with complex channels. However, enrichment from salmon overrode the effect of timber harvest on export during the run. Our study demonstrates that enrichment via SDN is short-lived and related to run size, whereas timber harvest and carcasses exert little influence on SDN dynamics.

Alternative silvicultural practices with variable retention to improve understory plant diversity conservation in southern Patagonian forests

Understory plants could can act as indicators of temperate forest sustainability, health and conservation status due to their importance in ecosystem function. Harvesting impacts on understory plant diversity depends on their intensity. Variable retention has been proposed to mitigate the harmful effects of timber harvesting, but its effectiveness remains unknown in southern Patagonian Nothofagus pumilio forests. The objectives of this study were to: (i) define a baseline of understory plant diversity in old-growth forests along a site quality gradient and under canopy gaps; (ii) evaluate stands with three different variable retention treatments compared to old-growth forests; and (iii) assess temporal changes during 4 years after harvesting (YAH). A 61 ha N. pumilio forest was selected. Understory plant (Dicotyledonae, Monocotyledonae and Pteridophyta) richness, cover (including woody debris and bare forest floor) and aboveground dry biomass were characterized in summer for 5 years. Before harvesting, baseline samples were conducted along a site quality gradient and outside/inside canopy gaps. Analyzed treatments include a control of old-growth forest (OGF) and three different harvesting treatments with variable retention: (i) dispersed retention (DR) of 30 m 2 ha −1 (20–30% retention); (ii) aggregated retention (AR) with one aggregate per hectare and clear-cuts (28% retention); and (iii) combined dispersed and aggregated retention (DAR) with one aggregate per hectare and dispersed retention of 10–15 m 2 ha −1 (40–50% retention). Data analyses included parametric and permutational ANOVAs, multivariate classification and ordinations. Before harvesting, 31 plant species were found, where richness, cover and biomass were directly related to site quality. The presence of canopy gaps did not have a significant impact on the measured variables. After harvesting, 20 new species appeared from adjacent associated environments (two from N. antarctica forests and 18 from grasslands and peatlands). At the stand level, understory values were higher in AR > DR > DAR > OGF. Most (81–95%) plant richness at baseline conditions was conserved in all treatments, where inside the aggregates understory remained similar to OGF. Combination of aggregated and dispersed retention (DAR) better limited exotic species introduction and protected sensitive species, improving conservation in harvested stands. Changes in understory variables were observed after the first YAH in all treatments; greater changes were observed in the harvested areas than in aggregates. Changes stabilized at the fourth YAH. As a conclusion, the location of retention aggregates should be selected to preserve species understory diversity of more speciose and diverse habitats or particularly uncommon stands. Implementation of different kinds (patterns and levels) of retention for improvement of biodiversity conservation in harvested forests should be included in timber and forest management planning.

Managing the forest for more than the trees: effects of experimental timber harvest on forest Lepidoptera

Studies of the effects of timber harvest on forest insect communities have rarely considered how disturbance from a range of harvest levels interacts with temporal variation in species diversity to affect community resistance to change. Here I report the results of a landscape-scale, before-and-after, treatment-control experiment designed to test how communities of forest Lepidoptera experience (1) changes in species richness and composition and (2) shifts in species dominance one year after logging. I sampled Lepidoptera from 20 forest stands allocated to three harvest treatments (control, even-aged shelterwood or clearcuts, and uneven-aged group selection cuts) within three watersheds at Morgan-Monroe State Forest, Indiana, USA. Moths were sampled from all forest stands one year prior to harvest in 2007 and immediately post-harvest in 2009. Species composition was most significantly affected by temporal variation between years, although uneven-aged management also caused significant changes in lepidopteran community structure. Furthermore, species richness of Lepidoptera was higher in 2007 compared to 2009 across all watersheds and forest stands. The decrease in species richness between years, however, was much larger in even-aged and uneven-aged management units compared to the control. Furthermore, matrix stands within the even-aged management unit demonstrated the highest resistance to species loss within any management unit. Species dominance was highly resistant to effects of timber harvest, with pre- and post-harvest values for Simpson diversity nearly invariant. Counter to prediction, however, the suite of dominant taxa differed dramatically among the three management units post-harvest. My results suggest that temporal variation may have strong interactions with timber harvest, precipitating loss of nearly 50% species richness from managed stands regardless of harvest level. Even-aged management, however, appeared to leave the smallest "footprint" on moth communities. Timber harvest also created greater heterogeneity in species dominance among management units, suggesting that forest watersheds may diverge in post-harvest recovery transients relative to unlogged watersheds in Morgan-Monroe State Forest. Because moth communities appear to be highly sensitive to group-selection cuts, shelterwood cuts, and clearcuts, it will be important to retain unlogged concessions within management units to resist landscape-level loss of Lepidoptera.

Integrated biodiversity monitoring for the jarrah (Eucalyptus marginata) forest in south-west Western Australia: the FORESTCHECK project

Summary The jarrah (Eucalyptus marginata) forest in south-west Western Australia is managed for a variety of land uses and supports a rich biodiversity recognised as being of national and international significance. FORESTCHECK, an integrated monitoring project, was established in 2001 to inform forest managers about changes and trends in key elements of forest biodiversity associated with a variety of management activities. FORESTCHECK monitoring is designed to provide information relevant to a number of regionallevel indicators of ecological sustainable forest management, and it samples a wide range of organisms at multiple sites across the main environmental gradients in the jarrah forest. Monitoring has focused initially on the effects of timber harvesting and associated silvicultural treatment including regeneration release through gap creation, regeneration establishment using shelterwood, and selective harvesting. Forty-eight monitoring grids, each 2 ha in size, have been established within four of the jarrah forest ecosystems mapped for the Western Australian Regional Forest Agreement. This series of papers present results from five years of data collection and examines the response of vascular plants, cryptogams, fungi, vertebrate and macro-invertebrate fauna to silvicultural treatment, including the planned use of fire. Responses of different elements of forest biodiversity are interpreted in relation to changes in forest structure and soil disturbance caused by treatment and underlying patterns of moisture availability and fertility across the forest landscape. The FORESTCHECK project contributes to adaptive management of Western Australian forests by providing timely and relevant information about the implementation and effectiveness of silvicultural practices.

Stream buffers ameliorate the effects of timber harvest on amphibians in the Cascade Range of Southern Washington, USA

We addressed the efficacy of stream-side buffers in ameliorating the effects of clearcut timber harvest on Cascade torrent salamanders ( Rhyacotriton cascadae), coastal/Cope's giant salamanders ( Dicamptodon tenebrosus/ D. copei), coastal tailed frogs ( Ascaphus truei), and water temperature regimes in the Cascade Range in southern Washington. Forty-one streams in 4 categories were sampled; streams in clearcuts with and without buffers, streams in 35+ year old second-growth forest, and streams in unharvested forest (150+ years old). Tailed frog and Cascade torrent salamander densities were 2–7-fold lower ( P < 0.05), respectively, in streams in managed forests than in streams in unharvested forest. In addition, both these species were less abundant ( P < 0.05) in unbuffered streams than streams with buffers or in second-growth forest. In contrast, giant salamander densities were 5–50% greater ( P > 0.05) in managed streams than unharvested, being greatest in unbuffered and second-growth streams. We used the differences in density estimates of unbuffered streams and unharvested streams to define an ecologically important effect size for each species and then compared the mean effect size and 95% confidence intervals of contrasts between managed stream categories to assess buffer effectiveness. Buffers had a positive ecologically important effect on the density of torrent salamanders and tailed frogs, but had an ecologically negative effect on giant salamanders. Water temperatures were similar among stream categories. However, Cascade torrent salamanders were nearly absent from streams where temperatures were ≥14 °C for ≥35 consecutive hours. Issues that need further study include effective buffer width and longitudinal extent, and confirmation of the water temperature threshold we identified.

Predicting the effects of woodcutting and moose browsing on forest development in Gros Morne National Park, Newfoundland, Canada

Long-term scenario analysis was used to predict the effects of domestic harvesting and moose (Alces alces) browsing on forest growing stock, species composition, and age-class distribution for two groups of managed forest blocks dominated by balsam fir (Abies balsamea [L.] Mill.) in Gros Morne National Park (GMNP), western Newfoundland. Four scenarios were examined. The first scenario assumed no timber harvesting and light moose browsing. Transition rules applied to this scenario came from neighbouring industrial forests, where moose populations are regulated by hunting. The other test scenarios use GMNP-specific transition rules to address increased moose browsing in the park, where hunting has been prohibitedsince the park’s inception in 1973. One of the three tested scenarios was also given a “no timber harvest treatment” so that the effects of moose browsing on park forests may be quantified by comparison with the first scenario. The two remaining test scenarios were designed to address compound effects of timber harvesting and moose browsing within the park, each representingan alternative management sce- nario currently being implemented in GMNP. For both harvest scenarios, the overall achievable wood volume was found to be at least five orders of magnitude lower than growing stock, thus providing sufficient volume for the ongoing domestic wood- cutting program (1973-2060) in the park. The proposed levels of woodcutting were predicted to have little impact on forest growing stock and old-growth forest after 160 years of management, but not on maintaining white birch (Betula papyrifera Marsh.), which is already in low numbers. In contrast, moose browsing, although it was predicted to have little effect on age-class distribution, was estimated to cause a 12% to 32% reduction in growing stock over a 160-year planning horizon, depending on the scenario. This was characterized by a 47% to 50% reduction in growing stock of balsam fir and a 50% to 87% reduction in white birch, and a commensurate expansion in low-density black spruce (Picea mariana [Mill.] BSP) and grassland cover. Key words: balsam fir, black spruce, domestic harvest, grassland, scenario analysis, white birch

Influence of harvesting intensity on the floristic composition of natural Mediterranean maritime pine forest

Understorey plant species composition is an important part of forest ecosystems and its conservation is becoming an increasingly frequent objective in forest management plans. However, there is a lack of knowledge of the effect of timber harvesting on the characteristic understorey species in the Mediterranean region. We investigated the effects of three different harvest intensities on the short-term dynamics of understorey vegetation in a natural Maritime pine forest in Spain, and compared the results with uncut controls. Clear-cutting induced both qualitative and quantitative differences with respect to the controls, but intermediate levels of harvesting (25% and 50% removal) induced only quantitative differences. Harvesting reduced the frequency and cover of 56% of characteristic forest species, but only 22% showed an increase. Of the most abundant plant families only the Fabaceae showed a significant response with respect to harvesting intensity. Our findings suggest that Light- and Medium-harvest regimes are better management options than clear-cutting if the aim is to conserve the understorey vegetation.

The effectiveness of different buffer widths for protecting water quality and macroinvertebrate and periphyton assemblages of headwater streams in Maine, USA

We evaluated the effect of timber harvesting on water quality and macroinvertebrate and periphyton assemblages in first-order streams in Maine, USA. Fifteen streams were assigned to one of five treatments: clearcutting without a stream buffer, clearcutting with 11 m buffers, clearcutting with 23 m buffers, partial harvesting with no designated buffer, and unharvested controls. Harvest blocks on both sides of the stream were 6 ha and partial harvesting within buffers was allowed. Specific conductivity, pH, dissolved oxygen, turbidity, and soluble reactive phosphorus did not change significantly for 3 years after harvesting in all treatments. Unbuffered streams had significantly elevated concentrations of chlorophyll a as well as increased abundance of algal feeding organisms (Diperta Cricotopus and Diptera Psectrocladius ). Streams with 11 m buffers had substantial (10-fold) but nonsignificant increases in chlorophyll a. No other significant changes were detected in other treatment groups. In all treatment groups, the dominant taxa (periphyton Achnanthes minutissimum and macroinvertebrate Chironomidae) are adapted to disturbed environments. We attribute the limited harvest-induced changes to lack of soil disturbance within 8 m of the stream, the small (≤40%) proportion of watersheds harvested, and the resilient nature of aquatic organisms. However, small-scale changes may not be detected due to the small sample size, an inherent limitation of field-based studies.

Preliminary investigation of the effects of timber harvesting on the activity status of beaver lodges in central Ontario, Canada

Beavers (Castor canadensis) are widely considered a keystone species in boreal and northern temperate forest ecosystems and are seasonally dependent on intolerant hardwood tree species for food. We used existing data to investigate the effects of timber harvesting on the activity status of beaver lodges in central Ontario, Canada. Beaver lodges were initially visited from 1976 to 1979 and active lodges were revisited in 1994. We analyzed a sample of 100 lodges. Fifty had some timber harvesting within 400 m of the lodge, 41 of which had harvest within 100 m of the shoreline (subsequently referred to as shoreline harvest). We differentiated timber harvest by type (clearcut vs. partial cut), years since harvest, and location for each lodge. Clearcut timber harvesting appeared to have a positive effect on the occupancy of beaver lodges. Seventy-three percent of lodges adjacent to shoreline clearcut areas were active, whereas only 34% of lodges with no shoreline harvest were active. We developed logistic regression models to evaluate the relationship between presence of timber harvest and activity status based on harvest location, harvest type, years since harvest, and water feature (pond, stream, lake, or wetland). Using Akaike’s Information Criterion, our modeling suggested that the presence of a 21- to 35-year-old shoreline clearcut adjacent to a lodge, combined with the associated water feature type, was the best predictor of lodge activity. However, our dataset included only a small sample of lodges in this harvest category (n = 11). While these results are viewed as preliminary, they do suggest that further investigation into the effects of shoreline timber harvest and shoreline reserves on habitat suitability for beavers is warranted. Key words: beaver, beaver pond, boreal, clearcut, forestry, Great Lakes – St. Lawrence, natural disturbance, Ontario, partial harvest, riparian, shoreline

Effects of Timber Harvest on Amphibian Populations: Understanding Mechanisms from Forest Experiments

Harvesting timber is a common form of land use that has the potential to cause declines in amphibian populations. It is essential to understand the behavior and fate of individuals and the resulting consequences for vital rates (birth, death, immigration, emigration) under different forest management conditions. We report on experimental studies conducted in three regions of the United States to identify mechanisms of responses by pond-breeding amphibians to timber harvest treatments. Our studies demonstrate that life stages related to oviposition and larval performance in the aquatic stage are sometimes affected positively by clearcutting, whereas effects on juvenile and adult terrestrial stages are mostly negative. Partial harvest treatments produced both positive and weaker negative responses than clearcut treatments. Mitigating the detrimental effects of canopy removal, higher surface temperature, and loss of soil-litter moisture in terrestrial habitats surrounding breeding ponds is critical to maintaining viable amphibian populations in managed forested landscapes.

Effects of Timber Harvest on Aquatic Macroinvertebrate Community Composition in a Northern Idaho Watershed

Abstract Annual macroinvertebrate sampling was performed from 1994 to 2005 in the Mica Creek Experimental Watershed in northern Idaho to examine the relationship between contemporary timber harvest practices and the structure and diversity of aquatic macroinvertebrate assemblages. Four years of calibration, 4 years of postroad, and 4 years of postharvest (roads + harvest) data were used to analyze treatment effects. Metrics used to assess change included functional feeding group composition, organism densities, taxa richness indices, species diversity, and sediment tolerance indices. These assessments included changes to three macroinvertebrate taxa commonly used as bioindicators of stream habitat quality: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddis flies) (EPT). In relation to pretreatment conditions, there were generally no major changes in functional feeding group composition or species diversity. Increases were observed in overall abundance and EPT abundance, but they largely can be explained by natural population variability. These results suggest that little or no change in macroinvertebrate communities resulted from road construction and timber harvest activities in the watershed. Substantial interannual variability was also observed, suggesting that infrequent biomonitoring may not provide adequate information to assess subtle disturbance effects in watersheds but can be an effective part of a comprehensive watershed monitoring program when coupled with other biotic and abiotic metrics.

Behavioral response of migrating wood frogs to experimental timber harvest surrounding wetlands

Behavioral responses to ecological disturbances such as timber harvest, fire, or drought provide insight into wildlife habitat requirements. To determine the behavioral response of adult wood frogs ( Lithobates sylvatica (LeConte, 1825)) to timber harvest in oak–hickory forest, we conducted experimental timber harvest surrounding replicate breeding sites, monitored freely moving frogs using radiotelemetry, and tested the repeatability of behavioral responses with two experimental displacements. We found no evidence that wood frogs use recent oak–hickory clearcuts as habitat. Timber harvest was not a complete barrier to movement, as frogs surviving increased predation and desiccation risks reached drainages used as nonbreeding habitat. Frogs did not alter the direction of travel and traversed similar distances (i.e., total distance and net distance from breeding site) before and after timber harvest. However, rate of travel (i.e., maximum distance traversed in 1 day) increased following timber harvest and frogs displaced to the center of clearcuts exited the timber harvest array in one rainy night. Notably, wood frogs following displacement exhibited site fidelity to nonbreeding habitat. We suggest that deleterious effects of timber harvest on amphibians may be minimized through the use of small stand sizes placed in locations that do not separate breeding and nonbreeding habitat.

Effects of timber harvest and other factors on a floodplain forest indicator species, the prothonotary warbler

Ecosystem approaches to management require monitoring of processes and species indicative of the integrity of the system in order to understand the effects of management and other perturbations. We examined the effects of three timber harvest options (single-tree selection, patch cuts, no harvest) on the reproductive biology of a possible indicator of bottomland forest ecosystem integrity, the prothonotary warbler (Protonotaria citrea). Timber harvests reduced the number of available nest cavities, reduced the density of breeding males on the plots, and increased the sizes of male territories. However, timber harvest had no obvious effect on nest predation or brood parasitism frequencies. Brood parasitism was instead related to distance from a nearby levee, a main source of brown-headed cowbirds (Molothrus ater) in the area. Productivity remained similar within suitable habitat regardless of treatment. Reproductive success was strongly influenced by annual variation, which we attribute to the timing and extent of annual flooding, a fundamental ecosystem process in floodplain forests. Continued anthropogenic alterations in flooding patterns may have a greater influence than current timber management on the future population levels of prothonotary warblers in the Mississippi Alluvial Valley. This species, with others, could play a valuable role in an ecosystem-oriented monitoring program.

Survival costs associated with wood frog breeding migrations: effects of timber harvest and drought

Migration presents a trade-off for individuals between the potential fitness benefits of reaching high-quality habitat vs. the potential costs of migration. Within an information-theoretic framework, we examined the costs of migration for adult wood frogs (Rana sylvatica) in response to timber harvest and annual weather conditions using Cox proportional-hazard estimates of survival. In 2004 prior to timber harvest, survival did not differ between the inside (0.75, SE = 0.078) and outside (0.73, SE = 0.235) of the circular timber harvest arrays (each 164 m radius). Following timber harvest, survival inside arrays in both 2005 and 2006 (0.22, SE = 0.065; 0.42, SE = 0.139) was lower than survival outside of the arrays and prior to harvest. Sources of mortality included predation in all years and desiccation in the drought year of 2005. The most-supported models for explaining both predation and desiccation risks reflected behaviors as opposed to timber harvest or weather conditions. Both predation and desiccation risks increased when frogs made frequent movements or were located near breeding ponds. Optimal behaviors for reducing predation and desiccation risks were the same before and after timber harvest; however, the survival consequences for not adopting these behaviors were more severe following harvest. Our results provide empirical evidence for (1) the ecological pressures that influence migratory behavior and (2) differential survival in relation to migratory behavior which reveals why frogs move relatively long distances away from breeding sites.

The effects of timber harvest, forest fire, and herbivores on regeneration of deciduous trees in boreal pine-dominated forests

Forest management, fire, and herbivores are the major factors affecting regeneration of deciduous trees in boreal forests. In a large-scale experiment, we manipulated the use of prescribed burning, the level of green-tree retention and the presence of moose ( Alces alces L.) and hare ( Lepus timidus L. and Lepus europaeus Pallas) to study their effects on early regeneration of three native pioneer tree species, i.e., rowan ( Sorbus aucuparia L.), aspen ( Populus tremula L.), and silver birch ( Betula pendula Roth). Green-tree retention enhanced survival of all tested tree species. Prescribed burning enhanced the survival rate of birch and rowan, but aspen survival was only enhanced by burning on clearcuts and areas with 50 m3/ha of retention trees. Excluding moose enhanced rowan growth and birch survival. Aspen growth and survival was enhanced when both moose and hare were excluded. Seedlings were most frequently browsed on clearcuts, and most seedling mortality was caused by voles or hare. At low densities, the effect of moose on pioneer trees may be smaller than that of other herbivores or the fire–management regime. Considering the large number of species depending on pioneer trees, the results support the use of tree retention and fire as useful management alternatives not only to promote biodiversity but also to enhance regeneration of deciduous trees and reduce herbivore damage.

Short-Term Effects of Timber Harvest and Weather on Northern Goshawk Reproduction in Northern Idaho

Abstract Nesting habitat of the Northern Goshawk (Accipiter gentilis) in North America has been associated with the amount of mature, closed-canopy forest in the nesting area; however, few studies have experimentally tested the effects of timber harvest on goshawk reproduction. We tested the effects of clear-cutting within goshawk nesting areas on reoccupancy and nesting success for two years following treatments. We also included habitat and weather variables as potential covariates in our models. We found no treatment effects on goshawk reoccupancy, nesting success, or number of fledglings between harvested and unharvested nesting areas. Our models suggested goshawk breeding area reoccupancy was a function of the amount of potential nesting habitat available in the 170-ha area surrounding the nest; goshawks reoccupied breeding areas if they contained >39% potential nesting habitat following harvest. Nesting success was correlated with mean April precipitation and January daily temperatures. Our results ...