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Understanding how land-management intensification shapes the relationships between biodiversity, yield, and economic benefit is critical for managing natural resources. Yet, manipulative experiments that test how herbicides affect these relationships are scarce, particularly in forest ecosystems where considerable time lags exist between harvest revenue and initial investments. We assessed these relationships by combining 7 yr of biodiversity surveys (>800 taxa) and forecasts of timber yield and economic return from a replicated, large-scale experiment that manipulated herbicide application intensity in operational timber plantations. Herbicides reduced species richness across trophic groups (-18%), but responses by higher-level trophic groups were more variable (0-38% reduction) than plant responses (-40%). Financial discounting, a conventional economic method to standardize past and future cash flows, strongly modified biodiversity-revenue relationships caused by management intensity. Despite a projected 28% timber yield gain with herbicides, biodiversity-revenue trade-offs were muted when opportunity costs were high (i.e., economic discount rates ≥7%). Although herbicides can drive biodiversity-yield trade-offs, under certain conditions, financial discounting provides opportunities to reconcile biodiversity conservation with revenue.

Managing forests intensively for timber production can homogenize forest structure and, in turn, alter species richness and functional composition of native species communities. Retention forestry, the practice of retaining structural elements during timber harvest, can increase species diversity in recently harvested forests, but its effect on functional trait diversity is less understood. We used a broad‐scale, replicated experiment to evaluate the effect of five tree retention patterns on species and functional trait diversity of ground beetles (Family: Carabidae) within early‐seral production forests in the Pacific Northwest, USA. We found no evidence for differences in carabid species or functional trait richness among treatments when considering species present in retention patches and adjacent clear‐cuts. However, we found evidence for lower taxonomic and functional trait variation between carabid communities present in retention patches and those present in clear‐cut areas of stands when retention was allocated to several small patches. Lower levels of functional trait variation in stands with several small patches were due to specialized predators found less often in small retention patches than in aggregated or riparian retention patches. Our findings indicate that relative to single large or riparian‐associated patches, small retention patches functioned similarly to clear‐cuts within harvested forests and several small patches did not increase species or functional trait richness. At current levels of retention in the region, allocation of trees to a single upland patch or split between riparian and upland patches can increase variation in ground beetle taxonomic and functional composition within harvested forests.

Structural enrichment in commercial tree plantations is a potential tool to increase snag numbers but relatively little information is available about how species, size, and spatial distribution of created snags are associated with longevity of these structures. We created 1197 snags in 31 harvest units from 1997 to 1999 in the Cascade and Coast Ranges, Oregon, USA, by topping live trees with harvesting equipment. We used an experimental design to distribute created snags at three densities and as either single or clumped created snags. We fit Weibull and log-logistic Accelerated Failure Time models and found that the median failure time was insensitive to the choice of distribution. We found a small positive effect of diameter at breast height (DBH) and a slight negative effect of increasing distance between created snags on survival. Assuming Weibull and log-logistic distributions at mean observed values of DBH and distance between snags, median survival times for Douglas-fir (Pseudotsuga menziesii) were 21.0 (95% confidence interval: 19.3, 22.8) years and 21.2 (19.7, 22.8) years, respectively. For western hemlock (Tsuga heterophylla), median survival times were 13.0 (11.9, 14.2) years and 12.5 (11.4, 13.7) years, respectively. Although the two failure distributions had similar median failure times, the log-logistic implies a higher survival probability over time for snags that remained standing at the end of the study period. Created snags can be a useful supplement for harvest units rotated at ∼45 years and Douglas-fir will be available for longer as standing structures. For example, under the log-logistic model, a predicted 5% of Douglas-fir snags are retained to rotation age, so that 40 snags per hectare would be required at harvest to maintain 2 snags per hectare through stand rotation. Snags created from western hemlock will provide an early rotation pulse but are unlikely to last longer than 20 years. Our results suggest that longevity can be increased by maximizing the snag size within the safety constraints of harvesting equipment. Scattering of snags may have a slightly negative effect on snag survival but this outcome should be weighed against potential ecological benefits of variation in snag distributions.

Black-backed Woodpeckers (Picoides arcticus) are widely considered a burned forest specialist across much of their range. Several recent studies have examined their occurrence in "green" coniferous forests that have not been recently burned, but Black-backed Woodpecker occupancy and factors influencing occupancy in these forest types remain largely unexamined. We worked on the east slope of the southern Oregon Cascade Mountains and used playback call surveys with repeated visits to 90 transects in 2014 and 2015 to estimate occupancy probabilities by forest type while controlling for detection probability. We detected Black-backed Woodpeckers on 86% of survey transects in green forests composed primarily of mixed conifer, lodgepole pine (Pinus contorta), or ponderosa pine (P. ponderosa). We examined associations between occupancy probability and structural covariates in unburned forests, and found that occupancy did not vary with annual precipitation, large snag density, or snag basal area. Modeled mean occupancy across all transects was 0.87 (95% CI: 0.78-0.93). Detection probability varied during each survey season, with transect-level detection probability reaching a maximum of 0.79 (95% CI: 0.70-0.85) in mid-June. Given high occupancy of green forests by Black-backed Woodpecker in our study area, we suggest that additional study of vital rates in green forests is critical for supporting conservation and management decisions for this species.

Retention forestry is a common practice for biodiversity conservation in forests managed for wood production. Retention forestry often leaves unharvested patches of trees that vary in size and spatial pattern but experiments evaluating the effects of different retention patch configurations at a constant level of retention are lacking for many regions and taxonomic groups. We implemented an experimental study in clearcut conifer stands with retention across the U.S. Pacific Northwest region. The study consisted of five stand-level (11–55 ha) experimental treatments each replicated 10 times within a randomized complete block design, resulting in 50 treated stands. Retained tree density was comparable across treatments but size, number, and location (upland or riparian) of patches within stands varied among the five treatments. Within experimental treatments, we measured small mammal (

By regulating populations of herbivores, predators can indirectly influence plant production. However, the factors influencing the strength of this type of trophic cascade are still unclear. We hypothesized that changes to plant community structure would affect the number of avian predators, thereby mediating cascade strength. Using a 4-yr, blocked, split-plot experiment, we independently manipulated both predators (birds) and plants in an early seral managed forest system in western Oregon, USA, and measured abundance across three trophic levels. We applied herbicides, as a surrogate for land-use intensification, to recently clear-cut stands to establish an experimental gradient in plant abundance and species richness, and excluded birds using 28, 225 m2 exclosures. In total, we counted and identified 94,738 arthropods of 141 families in paired control and bird exclosure plots. On average, insectivorous birds reduced arthropod abundance by 16% and plant damage by 14%, and some well-known pests (e.g., Adelges cooleyi) of crop trees (mostly Pseudotsuga menziesii) in our system were reduced by as much as 30%. However, this effect did not translate into a trophic cascade that increased crop-tree growth in the presence of birds. We experimentally reduced plant abundance and diversity by 67% and 55%, respectively, in the most intensive herbicide treatment in relation to untreated controls, but reduced vegetative resources did not change the strength of the direct effect of birds on arthropods or the indirect effect of birds on plants.

Black-throated Sparrows (Amphispiza bilineata) are common breeding birds throughout the desert regions of North America and can be considered nest-site generalists. Information about how spatial (e.g., vegetation) and temporal factors influence nest survival of these sparrows is lacking throughout their range. Our objective was to examine the spatial and temporal factors associated with nest survival of Black-throated Sparrows at the nest and nest-patch scales in the predator-rich environment of the northern Chihuahuan Desert of New Mexico. We used a logistic-exposure model fit within a Bayesian framework to model the daily survival probability of Black-throated Sparrow nests. Predation was the leading cause of nest failure, accounting for 86% of failed nests. We found evidence of negative associations between nest survival and both vegetative cover above nests and shrub density within 5 m of nests. We found no support for other habitat covariates, but did find strong evidence that daily survival rate was higher earlier in the breeding season and during the egg-laying stage. A decline in nest survival later in the breeding period may be due to increased predator activity due to warmer ambient temperatures, whereas lower survival during the incubation and nestling stages could be a result of increased activity at nests. A generalist approach to nest-site selection may be an adaptive response to the presence of a diverse assemblage of nest predators that results in the reduced influence of spatial factors on nest survival for Black-throated Sparrows.

Reductions in management intensity are often proposed to support a broader range of beneficial ecosystem responses than traditional management approaches. However, few studies evaluate ecosystem responses across approaches. Also, managers lack information about how species traits mediate responses across management approaches, a potentially substantial source of spatial and temporal variation in population and community responses that if ignored may hinder effectiveness of management programs. We used data collected over eight years from a manipulative experiment to test how four forest management strategies influenced avian community composition and wood production. After harvesting, we evaluated responses to three levels of plant cover suppression (Light, Moderate, and Intensive herbicide applications) in relation to a control without herbicide. We predicted the Moderate and Intensive treatments would exert strong negative effects on leaf-gleaning insectivores, including species of conservation concern due to long-term population declines. However, given high forest productivity, we expected temporal duration of effects to be short. Richness of leaf-gleaning bird species was reduced by 20-50% during the first four years post-harvest (when herbicide treatments were on-going), but the effect size declined over the next four years once treatments were completed (13-20% reduction). Effect sizes were substantially smaller for the non-leaf-gleaner group during years 1-4 (19-27%) and disappeared during years 5-8 (2-3%). However, in our final year of observation, we did find an average of five fewer non-leaf-gleaner species on Light vs. Control units. In the last two years of observation, turnover probabilities for the leaf-gleaner species remained higher on all treatments compared to the Control (0.11-0.21), indicating that new species continued to colonize treatments. Planted conifers were 40-44% taller and 74-81% larger in diameter in the Moderate and Intensive treatments compared to the Control, leading to substantial gains in wood biomass. Current practices provided more balance between two ecosystem responses, avian diversity and wood production, compared to less intensive alternatives. When short-term negative effects occur, the spatial distribution of harvesting and regeneration regionally indicates that habitat is often available locally to support leaf-gleaning and non-leaf-gleaning bird populations while releasing other portions of the region for high priority conservation objectives including late-successional forest reserves.

Early-successional forest birds, which depend on disturbance events within forested landscapes, have received increased conservation concern because of long-term population declines. Herbicides are often used to control vegetation within early-successional forests, with unknown effects on avian vital rates. We used a large-scale experiment to test how nest and post-fledging survival were influenced by herbicide intensity within managed conifer plantations across 2 breeding seasons. We created a gradient of 4 stand-scale herbicide treatments (light, moderate, and intensive, and no-spray control) and evaluated the reproductive response of the White-crowned Sparrow (Zonotrichia leucophrys), a declining songbird in managed forest landscapes of the Pacific Northwest. Against initial predictions, we found no evidence that either daily nest survival (n > 760 nests across all treatments) or post-fledging survival (n = 70 individuals reared in control and moderate treatments) were influenced by herbicide application intensity. Increased herbicide intensity resulted in an extensive reduction in vegetation cover at both stand and nest-patch scales; in contrast, vegetative cover at nest sites did not differ across herbicide treatments, nor was nest survival related to vegetation concealment measures. As the largest experimental investigation to assess forest herbicide effects on songbird demography, our study indicates that components of sparrow reproductive success were not influenced by experimental vegetation control measures, although additional work on other early-successional species will be useful to evaluate the generalities of our findings.

Retention forestry, the practice of maintaining stand legacies in harvested forests, is used to create more complex forest structure and positive biodiversity outcomes in managed forests. However, the relative effectiveness of different retention strategies at increasing forest structural complexity and populations of dependent wildlife species is not well understood. We used an experimental study to evaluate changes in the population density of three small mammal species in response to different size and location (riparian or upland) of retention tree patches within harvested forests in the Pacific Northwest, USA. We further assessed whether small mammal density varied in relation to differences in structural complexity within retention patches among experimental retention stands. Within stands, deer mice (Peromyscus spp.) population density did not differ between retention and harvested areas (β = −0.05, SE = 0.06), Townsend’s chipmunk (Neotamias townsendii) density was higher in retention compared to clearcut areas (β = 1.61, SE = 0.10), and creeping vole (Microtus oregoni) density was highest in clearcut areas (β = −0.68, SE = 0.10). At the stand-scale, deer mouse density and chipmunk density were lowest in stands with large upland patches of retention (mean = 83, SD = 28 trees) and highest in stands with multiple small patches of upland retention (mean = 8, SD = 2 trees). Creeping vole density followed the opposite pattern, highest in stands with large upland patches and lowest in stands with multiple small patches. Densities of each species were intermediate in stands where at least a portion of the retention trees were connected to forested riparian buffers. Relating the density of each species to structural complexity within stands revealed that Townsend’s chipmunk density increased with increasing retention tree blowdown (β = 0.39, SE = 0.08), a proxy for downed wood resources, whereas creeping vole density decreased (β = −0.51, SE = 0.12), and deer mice density did not change consistently (β = 0.00, SE = 0.08). Furthermore, retention tree mortality was highest in the experimental treatment with several small patches and lowest in the treatment with a single large patch. Our results demonstrate that adopting dispersed retention patch patterns increases the abundance of small mammals in managed, early-seral forests in the Pacific Northwest. This relationship is at least partly mediated through higher levels of structural complexity within small retention patches caused by increased retention tree blowdown compared to larger patches.

Summary 1.Tree plantations occur globally and are often promoted as a strategy to supply wood products for an expanding human population while reducing pressure on natural forests. Herbicides can accelerate growth of crop trees by suppressing competing vegetation, but little information is available about potential trade-offs with early seral biodiversity resulting from more intensive management. 2.Using data collected over five years immediately following stand-replacing disturbance (clear-felling), we used a large-scale experiment to test how environmental filtering influences dynamics of avian community assembly. We evaluated avian responses to three levels of plant cover reduction (Light, Moderate, and Intensive herbicide applications) in relation to a control without herbicide. Under the environmental filtering hypothesis, we expected reduced avian species richness and higher turnover as broadleaf plant cover decreases with increasing management intensity. We predicted that the most intensive treatments would exert strong negative effects on leaf-gleaning insectivores, including several species of conservation concern due to long-term population declines. 3.Richness of leaf-gleaning bird species was reduced by 23-52% over the five years on Moderate (standard practice) vs. control treatments, but effects were substantially smaller for the non-leaf-gleaner guild in years 1-4 (8-25%) and disappeared by year 5 (0%). Both leaf-gleaner and non-leaf-gleaner functional groups continued to colonize Moderate and Intensive treatments at higher probabilities than the control in Year 5 (range: 0.17-0.29), likely due to rapid vegetation recovery after herbicide applications ceased. Planted conifers were >35% taller and >70% larger in diameter in the two most intensive treatments, leading to substantially more wood volume produced per unit area than on stands without herbicide applications. 4.Synthesis and applications. Under current management regimes, stand-level trade-offs between conservation of avian diversity and production of wood commodities may be less severe than previously recognized. However, in landscapes where biodiversity conservation rather than wood production is the primary goal, managers can adjust the trade-off by making relatively small reductions in herbicide use that should have positive impacts on richness of leaf-gleaning insectivorous birds. This article is protected by copyright. All rights reserved.

Understanding how natural and anthropogenic disturbances affect sensitive species is critical to support conservation programs as land use activities and climatic conditions change. Forest management provides a range of ecosystem services to expanding human populations including production of substantial amounts of woody biomass, thereby reducing area under management and increasing opportunity for conservation designations. However, relatively little experimental information is available to describe how manipulating habitat at multiple scales may affect spatial and temporal variation in populations of climate-sensitive forest taxa. We conducted a Before-After Control-Impact experiment over seven years to evaluate responses of two species of Plethodontid salamanders in operational treatment (harvest, replanting, and herbicide application) and control units, Oregon, USA. In addition, we capitalized on existing variation in downed wood size and accounted for potential behavioral responses to evaluate the thermal refugia hypothesis. For Oregon slender salamanders (Batrachoseps wrighti), mean plot-level occupancy (90% CRI) was increased an estimated 11% (1.11; 0.62–2.1) and estimated mean abundance reduced 16% (0.84; 0.54–1.4) post-harvest. For Ensatina (Ensatina eschscholtzii), mean occupancy was reduced an estimated 80% (0.20; 0.08–0.47) and estimated mean abundance reduced 63% (0.37; 0.22–0.65) post-harvest. We found strong evidence of positive associations for both species with downed wood amount. As predicted, we found ambient temperatures to be higher in harvest than control units. Also, internal downed wood temperatures were warmer in harvested units, suggesting these structures may not have provided adequate thermal refugia. Application of an experimental framework provided evidence about both stand and structure level responses to active management. Habitat structures did not appear to buffer against substantial variation in local climate but evidence was equivocal about importance of these structures to population retention. Monitoring of recruitment and retention of downed wood through subsequent rotations can provide critical information to reduce trade-offs between wood production and conservation of climate sensitive taxa.

The ecological value of unmanaged early successional habitat created by disturbances has received considerable research attention. Less well studied is the capacity of tree plantations to contribute to local and regional biological diversity while subsidizing conservation strategies. We present a conceptual framework for describing variability in early successional forests and illustrate how the spatial pattern of this habitat may vary as a function of productivity, land ownership, and disturbance in the Pacific Northwest, USA. We posit that plantations will only increase in ecological and economic importance as the world addresses conservation and resource production challenges associated with climate change, altered disturbance regimes, increasing rates of global wood consumption, and evolving social, legal, and economic expectations. Researchers and managers can foster collaborative frameworks to encourage provisioning of non-timber services on private land, while prioritizing non-timber benefits of early successional habitat on public land to optimize biodiversity conservation and ecosystem services provided in managed forest landscapes.

Intensively-managed forest (IMF) ecosystems support environmental processes, retain biodiversity and reduce pressure to extract wood products from other forests, but may affect species, such as plethodontid salamanders, that are associated with closed canopies and possess limited vagility. We describe: (1) critical aspects of IMF ecosystems; (2) effectiveness of plethodontid salamanders as barometers of forest change; (3) two case studies of relationships between salamanders and coarse woody debris (CWD); and (4) research needs for effective management of salamanders in IMF ecosystems. Although plethodontid salamanders are sensitive to microclimate changes, their role as ecological indicators rarely have been evaluated quantitatively. Our case studies of CWD and salamanders in western and eastern forests demonstrated effects of species, region and spatial scale on the existence and strength of relationships between plethodontid species and a “critical” microhabitat variable. Oregon slender salamanders (Batrachoseps wrighti) were more strongly associated with abundance of CWD in managed second growth forests than ensatina salamanders (Ensatina eschscholtzii). Similarly, CWD was not an important predictor of abundance of Appalachian salamanders in managed hardwood forest. Gaining knowledge of salamanders in IMF ecosystems is critical to reconciling ecological and economic objectives of intensive forest management, but faces challenges in design and implementation.

As human demand for ecosystem products increases, managers of landscapes used for commodity production require information about effects of management regimes on biological diversity. Landscape attributes, however, may moderate ecological responses to local-scale conservation and management actions. As a result, uniform application of local management prescriptions may yield variable biodiversity responses. We examined how interactions between local habitat structure and landscape forest cover were associated with avian community composition in the Ouachita Mountains, Arkansas, USA, 1995–1998. We used Bayesian hierarchical models to estimate occupancy for 63 breeding bird species, while accounting for variable detection with data collected from 1941 temporally replicated point count stations. Specifically, we estimated how interactions of four local habitat covariates (canopy cover of mature coniferous and hardwood trees, number of snags, and shrub cover) with percentage of mature hardwood forest at the landscape scale were associated with species occupancy and richness. Average predictive comparisons indicated that snag count and shrub cover had the strongest associations with species richness. Estimated associations for each of the four local forest cover variables was similar across all levels of landscape forest cover, suggesting weak or negligible interactions between these local measures and the landscape covariate. We found little support for our main prediction that local/landscape habitat interactions would be strongest at low levels of landscape forest cover (1–20%). Consequently, we suggest that forest managers consider prescriptions that result in a broad spatial distribution of heterogeneous habitat structural conditions (e.g., variation in understory cover and composition), irrespective of landscape context, to maintain a diverse avian breeding assemblage on landscapes in this region.

Forest management guidelines for rare or declining species in the Pacific Northwest, USA, include both late successional reserves and specific vegetation management criteria. However, whether current management practices for well-studied species such as northern spotted owls (Strix occidentallis caurina) can aid in conserving a lesser known subspecies-Humboldt martens (Martes caurina humboldtensis)-is unclear. To address the lack of information for martens in coastal Oregon, USA, we quantified vegetation characteristics at locations used by Humboldt martens and spotted owls in two regions (central and southern coast) and at two spatial scales (the site level summarizing extensive vegetation surveys and regionally using remotely sensed vegetation and estimated habitat models). We estimated amount of predicted habitat for both species in established reserves. If predicted overlap in established reserves was low, then we reported vegetation characteristics to inform potential locations for reserves or management opportunities. In the Central Coast, very little overlap existed in vegetation characteristics between Humboldt martens and spotted owls at either the site or regional level. Humboldt martens occurred in young forests composed of small diameter trees with few snags or downed logs. Humboldt martens were also found in areas with very dense vegetation when overstory canopy and shrub cover percentages were combined. In the South Coast, Humboldt martens occurred in forests with smaller diameter trees than spotted owl sites on average. Coastal Humboldt martens may use stands of predicted high quality spotted owl habitat in the Pacific Northwest. Nonetheless, our observations suggest that coastal Humboldt martens exist in areas that include a much higher diversity of conifer size classes as long as extensive dense shrub cover, predominantly in the form of high salal and evergreen huckleberry, are available. We suggest that managers consider how structural characteristics (e.g., downed logs, shrub cover, patch size), are associated with long-term species persistence rather than relying on reserves based on broad cover types. Describing vegetation may partially describe suitability, but available prey or predation risk ultimately influence likelihood of individual Humboldt marten use. Guidelines for diversifying vegetation management, and retaining or restoring appropriate habitat conditions at both the stand level and regionally, may increase management flexibility and identify forest conditions that support both spotted owls and Humboldt martens.

Components of biodiversity in intensively managed forest stands may be reduced in comparison to naturally regenerated stands. Use of herbicides to suppress herbaceous and woody plant species that compete with planted seedlings has been implicated in negative impacts. We designed a large-scale experimental study to test the influence of intensive forest management on the abundance of early seral bird species in the Oregon Coast Range, US. Experimental applications consisted of ‘Intensive’ (i.e., heavy use of herbicides), ‘Moderate’ and ‘Light’ treatments, as well as controls with no herbicide application. In relation to the control, abundance of six out of thirteen bird species was significantly reduced in at least one of the three treatments. Leaf-gleaning insectivorous birds were more negatively affected by heavier herbicide treatments in general than bird species with other foraging behavior. Long-term bird population trends, derived from the Breeding Bird Survey, were correlated with the effect of intensive treatment; species more negatively associated with intensive treatments at the stand scale, were more likely to be in decline across the Pacific Northwest, US. Our results also indicate that reducing intensity of herbicide applications has positive effects on early seral bird abundance during the first 2 years of stand growth – particularly those species exhibiting negative population trends. To balance biodiversity conservation and timber production, research examining the tradeoffs between reduced application of herbicide and tree growth is required.

Parental roles in nestling provisioning and composition of prey brought to nestlings are not well-studied for North American woodpeckers (Picidae). We studied nestling diets and the role of adult Hairy (Picoides villosus) and White-headed woodpeckers (Picoides albolarvatus) in provisioning nestlings and nest sanitation during 2009–2011 in managed ponderosa pine (Pinus ponderosa) forests, Cascade Range, Washington, USA. Male White-headed Woodpeckers removed fecal material from cavities more frequently than females; a difference we did not observe between sexes in Hairy Woodpeckers. Male and female White-headed Woodpeckers, and female Hairy Woodpeckers, fed significantly more small (beak closed when holding prey) than large prey (beak unable to close when holding prey) to nestlings. We did not find differences in provisioning rates by sex of the parent, by nestling age, or by date of provisioning trip for either species. Morisita's Index (C) of diet overlap showed a large similarity in the nestling...

Harvest of forest biomass, specifically downed woody material (DWM), will increase to meet rising demand for alternative energy sources. Biomass harvest may reduce habitat quality, abundance, and regional diversity of forest-dependent species such as amphibians. We synthesize available literature conducted in landscapes managed for timber production to (1) assess the current state of knowledge regarding DWM management and amphibian population dynamics and (2) identify pertinent research gaps for future biomass studies. In general, the 25 studies we reviewed reported that amphibian counts were positively correlated with DWM levels. Although studies involving terrestrial salamanders often stressed the importance of retaining DWM in harvested systems, empirical support for this conclusion is uncertain due to study- and species-specific variation in responses. Lack of a DWM effect was often attributed to downed wood that was not well decayed or was too small for amphibian use. We identified several critical research needs, including: (1) understanding temporal dynamics of DWM (e.g., recruitment and decay rates) in regenerating forests and its influence on amphibian populations, (2) determining how amphibian use of harvest units relates to configuration and characteristics of DWM, (3) understanding how DWM management influences amphibian demographic rates, and (4) development of sampling and analytical techniques that support separation of sampling error and ecological effects. We suggest that future studies estimate effects of biomass harvest and identify, test, and refine operational harvest strategies that minimize impacts to amphibian populations. We emphasize research should be conducted at scales relevant to management; specifically, stand and landscape scales.

The dynamics of species interactions are critical to understanding community ecology. Although species co-occurrence models have long been available, recent methodological advances support extensions to incorporate temporal population dynamics with variation in the observation process. Contemporary dynamic co-occurrence models often focus on simple presence/absence despite evidence that the influence of interactions may extend beyond species presence to behaviors influencing fitness such as mating success or recruitment. Here, we propose a joint model of species interaction dynamics that extends to multistate processes for each species, while limiting the attendant combinatorial expansion in the number of parameters. In our model, one or more states of a subordinate species are assumed to depend on the state of a dominant species, but a reciprocal dependency does not exist. This model results in a more concise representation of dominant-subordinate species interactions compared with other approaches, which should aid in model setup, fitting, and interpretation. The basic framework we outline can be fit in either Bayesian or maximum-likelihood modes of inference, can include interaction lag effects, and deals efficiently with cases where data are missing for one species but not the other. We evaluate interactions between the northern spotted owl (Strix occidentalis caurina) and barred owl (Strix varia)—the latter species is considered to be dominant—using long-term empirical data collected in Oregon, USA. Our results suggest state-specific interactions between the two species where barred owls are associated with declines in spotted owl pairings, but not necessarily occupancy.

Conservation and management programs use populations of sentinel taxa, such as stream-associated amphibians, as indicator species due to their perceived sensitivity to environmental change. Estimating population size with traditional tools such as mark–recapture estimators may be impractical for forest-dwelling stream-associated amphibians, many of which are cryptic and have low detection probabilities. In addition, sampling techniques can alter habitat conditions, particularly with repeat sampling, and compromise inferences about management impacts. We used simulated and empirical data and N-mixture models to estimate detection probabilities and abundances for two amphibian genera, giant Dicamptodon and torrent Rhyacotriton salamanders, sampled with a less-invasive approach than other methods. We surveyed forested headwater streams located in western Washington, USA, for salamanders 7 July–27 August 2008. We assessed model sensitivity to changes in animal abundance (5 and 15) and detection probability (0.05–0.5), as well as study design alternatives including number of sample plots (50–150) and number of sampling visits (2–4). We also evaluated the effects of stream temperature and stream order on detection probability using data collected from forested streams in Washington, USA. Precision of detection probability estimates improved as the number of plots and sampling occasions increased. Variability of estimated population sizes decreased with higher detection probability, although species abundance had little effect on precision of detection probability estimates. Detection probability estimated from empirical data ranged from 0.07 to 0.65 for giant salamanders and 0.06–0.67 for torrent salamanders. Giant salamander detection probability was positively associated with stream temperature regardless of stream order, and was higher in second- and third-order streams than first-order streams. Detection probability for torrent salamanders varied with stream temperature, order, and the interaction of those covariates, with detection increasing with temperature for second- and third-order streams but showing a flat or decreasing trend for first-order streams. N-mixture models, paired with careful consideration of study design alternatives, can produce robust estimates of abundance and obviate the traditional reliance on indices of relative abundance for many rare and sensitive taxa. Use of a less invasive technique for sampling stream-associated amphibians resulted in sufficient animal captures for suitable model performance. Our simulation results can inform study design and direct efficient allocation of field effort.

Structure retention is a practice used in managed forests to assist the conservation of biological diversity, whereby green trees, dead trees (i.e. snags), and downed wood are retained during timber harvest. This activity is recognized as beneficial. However, there is little scientific support to guide the management prescriptions (e.g. patch sizes, distribution pattern). We quantified the short-term response of birds to structure retention in timber harvest areas located in the Pacific Northwest. We used a hierarchical community model to examine how attributes of retention sites (number of trees and snags, distance to forest edge) were associated with the species richness of birds using the sites. The modeling framework integrated multiple species-specific occupancy models that accounted for imperfect detection to produce estimates of species richness. We sampled a biogeoclimatic gradient by selecting harvest units within four separate regions (two in Washington, one each in Oregon and California) that support different forest types. Observations were conducted at a random selection of retention sites (e.g. patches, individual trees) within harvest units to record bird use during the breeding seasons of 2008 and 2009. Estimated occupancy and detection probabilities differed by species and region. Retained tree count was associated with an increased occupancy probability for all observed species. The community response to tree count was consistent across all study regions and years – species richness estimates increased with tree count and approximated a species–area curve. Snag count and edge distance did not significantly affect occupancy probability for any observed species, and therefore, had no relationship with species richness. These results suggest that the diversity of birds using structure retention in harvest units can be maximized at patches of >10–15 rotation-age trees. Forest managers are encouraged to group green-trees around high-quality snags and other unique wildlife trees where possible, and to vary prescriptions across stands to provide habitat heterogeneity at the landscape scale.

Managers of landscapes dedicated to commodity production require information about how alternative practices can promote retention of native biological diversity. Retaining or creating structural features (e.g., snags or downed logs) needed to fulfill life history requirements may benefit populations and communities. However, demographic responses of species to alternative practices have received little research attention. We tested nest survival of cavity-dependent birds in response to experimental structural enrichment by creating snags on 28 plots, Oregon, USA, 2008–2010. Each plot represented one of six combinations of created snag density (0.5, 1, and 2 snags/ha) and spatial dispersion (clumps of 5–7 snags or dispersed individual snags). We monitored 506 nests built by 10 species; three species nested in sufficient numbers for analysis. Chestnut-backed chickadee Poecile rufescens nest success was highest in the medium density clumped created snag treatment (average proportion of successful nests = 0.76; 95% CI = 0.61–0.87) and lowest in the low density clumped treatment (average proportion of successful nests = 0.39; 95% CI = 0.20–0.62). We did not find a response of either house wren Troglodytes aedon or northern flicker Colaptes auratus nest success to the experimental treatments. Period survival rates were 0.57 (95% CL: 0.39–0.72) for CBCH; 0.71 (95% CL: 0.51–0.84) for HOWR; and 0.59 (95% CL: 0.34–0.77) for NOFL. Our study suggests that creating snags in commercial harvest units is an effective practice for increasing structural complexity and supporting nesting communities of cavity-dependent birds. While leaving either clumped or dispersed created snags at a density of ∼1 ha should support nest survival rates that are similar to those reported from unmanaged forests, we emphasize that this type of structural enrichment is not a panacea for species that require very large snags or snags that occur under complex forest canopies. Retention of existing structural features in reserve areas may be an appropriate practice for conserving species with nesting requirements that differ from those we evaluated in our study.

Landscape composition may have a substantial influence on species use of habitat at local scales and effectiveness of structural enrichment practices (e.g., augmenting existing amounts of snags or downed logs). If sufficient mature (i.e., cavity containing) habitat exists at the landscape scale, cavity nester demand for nest sites could be reduced due to the surplus of existing sites ( habitat surplus hypothesis ). Alternatively, if mature forest acts as source habitat for cavity nesters, increased amounts of mature forest in the landscape will inflate the demand for snags in clearcuts ( habitat source hypothesis ). In Oregon, USA, we evaluated cavity nesting bird colonization of experimentally created snags distributed across a gradient in amount of mature forest at the landscape scale. We sampled 28 plots, each of which represented one of six combinations of created snag density (∼0.5, 1, and 2 snags/ha) and spatial dispersion (clumps of 5–7 snags or dispersed individual snags). We tested whether early successional and mature forest species groups responded differently to plot-level treatments and if the percentage of mature forest (>40 years old) within a 1000 m radius surrounding each experimental plot influenced this response. Mature forest species more readily colonized created snags as the percentage of mature forest declined in the landscape, supporting the habitat surplus hypothesis . Estimated use by mature forest species increased from 7% to 17% as percent mature forest in the landscape declined from 58% to 13% (estimated for average levels of created snag density, 0.4 snags/ha, and a spatial distribution of 45 m). Colonization of snags by early seral species also increased with decreasing mature forest (from 3% to 9%), which may support the habitat source hypothesis . Our study suggests that creating snags in commercial harvest units is an effective practice for increasing structural complexity and maintaining nesting communities of cavity-dependent birds. At the local level, created snags should be spaced as widely as possible within individual harvest units. However, our results indicate that effectiveness of snag creation will be highest in the most intensively managed landscapes where the amount of structurally diverse habitat is limited.

Recent evidence suggests that population declines of bird species associated with early-successional forest conditions may be associated with reduced quality of breeding habitat. Increasing intensity of forest management on private lands and decreased harvest rates on federal lands in the Pacific Northwest, USA, have resulted in a loss of diverse young forest stands, typically called early seral forest. Previous studies suggest that the amount of early seral broadleaf cover within conifer forests is linked to the composition of foliage-gleaning bird communities. However, information regarding productivity and juvenile use of post-breeding habitat in highly modified plantation habitat is lacking. We examined the relationship between vegetation structure resulting from intensive forest management practices and the abundance of five species of leaf-gleaning, neotropical migrants: orange-crowned warbler ( Oreothlypis celata (Say, 1823)), Wilson’s warbler ( Wilsonia pusilla (A. Wilson, 1811)), MacGillivray’s warbler ( Oporornis tolmiei (J.K. Townsend, 1839)), Swainson’s thrush ( Catharus ustulatus (Nuttall, 1840)), and black-headed grosbeak ( Pheucticus melanocephalus (Swainson, 1827)). All species, except MacGillivray’s warbler, showed positive associations with the amount of early seral hardwood cover as fledglings, breeding adults, or both. However, the relative magnitude of these associations varied, suggesting that other factors may also have influenced avian responses. Abundances of breeding pairs and young are likely to show positive responses to management practices that increase early seral hardwood cover in regenerating stands. If adopted at landscape and regional scales, such practices may positively influence population trends of several declining bird species.

Evaluating spatial and temporal variation in abundance due to anthropogenic and environmental disturbances is a central aspect of wildlife ecology and management. We conducted an experiment to evaluate the effects of salvage logging on the abundance of 22 avian species and 6 foraging guilds in lodgepole pine (Pinus contorta) forests affected by beetle outbreaks, south-central Oregon, USA, 1996–1998. Treatments consisted of the removal of lodgepole pine snags only; live trees and ponderosa pine snags were not harvested. Our hierarchical model requires replicated count data from multiple sample units across several time periods, during which the population is closed, to estimate abundance as a function of logging treatment and management district while accounting for imperfect and variable detection probability. We fit the model to point counts from 12 control and 12 treatment plots with 3 surveys during each breeding season, 1996–1998. We found evidence for a large, but imprecise, effect of salvage logging in all 3 years for only 1 species, the gray flycatcher (Empidonax wrightii). The abundance of the remaining species either did not change or displayed weak positive responses to the treatment. Although 3 foraging guilds increased in total abundance, 2 guilds did not change and the response of 1 guild changed direction in different years. Our results suggest that, unlike most postfire salvage logging prescriptions, selective harvesting after beetle outbreaks may meet multiple management objectives, including the maintenance of avian population sizes comparable to those found in unharvested stands. Future research should consider different sampling programs for those species with large home ranges (e.g., woodpeckers) that may not be sampled adequately using commonly employed programs (e.g., point count stations). © 2012 The Wildlife Society.

Northern spotted owls (Strix occidentalis caurina) have received intense research and manage- ment interest since their listing as a threatened species by the United States Fish and Wildlife Service in 1990. For example, public and private forest managers in the Pacific Northwest, USA, conduct surveys to determine presence or absence of spotted owls prior to timber harvest operations. However, although recently developed statistical methods have been applied to presence-absence data collected during research surveys, the effectiveness of operational surveys for detecting spotted owls and evaluating site occupancy dynamics is not known. We used spotted owl survey data collected from 1995 to 2009 on a study area in interior northern California, USA, to evaluate competing occupancy models from Program PRESENCE using Akaike's Information Criterion (AIC). During 1,282 individual surveys, we recorded 480 spotted owl detections (37.4%) and 13 barred owl (1.0%) detections. Average per visit detection probability (85% CL) for single and paired spotted owls was 0.93 (0.90-0.96) for informed daytime, stand-based searches and 0.47 (0.43-0.51) for nighttime, station-based surveys (estimated from the best model); the average per visit detection probability from the null model was 0.67 (0.64-0.70). Average pair-only detection probabilities were 0.86 (0.81-0.90) for informed daytime, stand-based searches and 0.23 (0.18-0.29) for nighttime, sta- tion-based surveys; the average per visit detection probability from the null model was 0.63 (0.58-0.68). Site occupancy for any owl declined from 0.81 (0.59-0.93) in 1995 to 0.50 (0.39-0.60) in 2009; pair occupancy declined from 0.75 (0.56-0.87) to 0.46 (0.31-0.61). Our results suggest that a combination of 1 informed stand and 2 station-based operational surveys can support determinations of spotted owl site status (either a single or a pair) at desired levels of confidence. However, our information was collected in an area where barred owls were rarely detected. Surveys conducted in areas that support well-established barred owl populations are likely to be less effective for determining presence or absence of spotted owls and may require more surveys and/or different survey methods to determine site status with confidence. 2012 The Wildlife Society.

Woodpeckers are particularly susceptible to habitat changes resulting from forest management because of their reliance on trees and snags for nesting and foraging. However, the influence of habitat variables on the reproductive success of woodpeckers has received less attention than it has in other avian taxonomic groups. We estimated nest-survival rates for the White-headed Woodpecker (Picoides albolarvatus), Hairy Woodpecker (P. villosus), and Northern Flicker (Colaptes auratus) in managed ponderosa pine (Pinus ponderosa) forests along the eastern slope of the Cascade Range in Washington, 2005–2010. Using a model-selection framework, we found that the most supported models included terms for a quadratic effect of date and habitat type for the Hairy Woodpecker, a negative effect of percent shrub cover for the White-headed Woodpecker, and a negative linear effect of date and habitat type, a negative linear effect of snag density, and a positive linear effect of tree density for the flicker. Surv...

Large-scale amphibian conservation often relies on remotely sensed data to describe spatial patterns in occupancy. Commonly used data include ownership, forest type, soil class, and proximity of wetlands. We evaluated the influence of these variables on terrestrial amphibian occupancy in southern Michigan. We trapped amphibians using drift-fence arrays in 82 forest patches and estimated detection probabilities for all captured species. Ten species were captured, but only three were detected at levels suitable for occupancy modeling. We concluded that drift-fence arrays alone were not sufficient for adequately detecting the majority of terrestrial amphibians. The best detection models for American Toad (Anaxyrus americanus), Wood Frog (Lithobates sylvaticus), and Spring Peeper (Pseudacris crucifer) consistently included a positive relationship with temperature and precipitation. Detection-adjusted occupancy models for the three anurans indicated relatively high occupancy (>0.43). Ownership, forest...

Snags are critical structural features for managing biological diversity in forests of the Pacific Northwest, USA. However, commercial forests in this region often contain reduced numbers of snags compared to unmanaged forests and managers require effective methods to augment snag numbers in harvest units. Therefore, we created snags by topping live trees with a mechanical harvester and studied foraging and nesting use by cavity-nesting birds of these snags in clearcuts in Douglas-fir ( Pseudotsuga mensezii ) forests along the west slope of the Cascade Mountain Range and east slope of the Coast Range in Oregon, USA. We used a completely randomized design to assign 6 different treatments (single or scattered distribution by 3 different densities) to 31 different harvest units. We created 1111 snags from February 1997 through April 1999 and monitored them from 2–5 years after harvest (1999–2002). Fraction of created snags with nest cavities in harvest units was generally low across all treatments and years of the study, although some individual stands demonstrated increased nesting use with snag age. While the highest fractions of snags with nest cavities were found in units with low density and scattered snags, the mean fraction of snags used for nesting did not differ among treatments. Treatment type, distribution of snags (i.e., scattered or clumped), and associated interactions did not influence fraction of snags used for foraging. However, fraction of created snags used for foraging in all harvest units increased with snag age. Fraction of snags used for foraging was greatest in the low density treatments. While this technique provides managers with a relatively economical option for creating snags, mechanical harvesters cannot be used to create tall, large snags upon which several cavity-dependent species rely and provides only a partial solution to a critical forest management issue.

Information about the immediate and potentially prolonged impacts of salvage logging is needed to develop prescriptions that maintain forest productivity, reduce the risk of catastrophic fires, and conserve biological communities. Most salvage logging studies have investigated post-fire salvage, often clearcutting, and impacts documented in these studies may be more severe than selective logging prescriptions applied to forests affected by beetle outbreaks. We evaluated the effects of selective salvage logging on avian nest survival in beetle-killed lodgepole pine ( Pinus contorta ) forests on the Fremont and Winema National Forests, south-central Oregon, USA, 1997–1999. Using logistic-exposure models, we found that nest survival for weak (period nest survival: 0.64; 95% CL: 0.50, 0.75) and strong (period nest survival: 0.71; 95% CL: 0.46, 0.87) cavity nesters was significantly higher than for ground nesters (period nest survival: 0.31; 95% CL: 0.18, 0.46), while nest survival for open cup nesting birds (period nest survival: 0.57; 95% CL: 0.47, 0.66) was intermediate. We did not find significant differences in nest survival for American robin ( Turdus migratorius ), chipping sparrow ( Spizella passerine ), dark-eyed junco ( Junco hyemalis ), dusky flycatcher ( Empidonax oberholseri ), mountain chickadee ( Poecile gambeli ), or yellow-rumped warbler ( Dendroica coronata ) (these six species comprised ∼80% of the sample). Our results suggest that, unlike post-fire salvage logging, selective harvesting prescriptions after beetle outbreaks may be suitable for meeting multiple management objectives, including generating a flow of commodities and maintaining avian nest survival rates.

Conservation and management of native species on landscapes managed for intensive wood production represents an ongoing challenge to forest managers. Previous research suggests that impacts of forest practices on stream-associated amphibians (SAA; giant [Dicamptodon spp.], torrent [Rhyacotriton spp.], and plethodontid [Plethodon spp.] salamanders and coastal tailed frogs [Ascaphus truei]) in Oregon and Washington, USA, vary spatially and temporally as a result of biotic and abiotic factors, some of which can be influenced by management treatments. Although individual harvest units can encompass multiple stream reaches and entire second-order basins, nearly all published research studies used stream reaches of various lengths as sample units. To address this discrepancy between research and operational scales, we sampled first-, second-, and third-order streams in 70 randomly selected third-order basins in Oregon and Washington in 2007 and 2008 to estimate detection and occupancy parameters for SA...

Northern spotted owls (Strix occidentalis caurina) have received intense research and management interest since their listing as a threatened species by the United States Fish and Wildlife Service in 1990. Several spotted owl (Strix occidentalis) response variables have been examined in various investigations, but recent advances in statistical modeling permit evaluations of temporal and spatial variability in site occupancy, local-extinction, and colonization probabilities while incorporating imperfect detection probabilities. Following recent work by other researchers on site occupancy dynamics of spotted owls in Oregon, USA, we evaluated temporal variability of detection, occupancy, local-extinction, and colonization probabilities for spotted owls, as well as potential influences of barred owl (Strix varia) presence on these parameters. We used spotted owl survey data collected from 1990 to 2003 on a study area in the eastern Cascades Mountains, Washington, USA, to compare competing occupancy ...

Effective management of forest wildlife requires information about habitat features that can be altered by operations, if those habitat features promote reproductive success and survival, and if changes in organism density influence reproductive success and survival. Habitat selection studies often provide the first type of information, although relatively few studies examine how different selection decisions or densities of organisms influence fitness measures or measure habitat features at relevant operational scales. We examined patterns of habitat selection and estimated how habitat use, territory size, and conspecific density were associated with territory success (probability of a territory producing one or more fledglings) for the dusky flycatcher in 2002–2003 on eight study plots in managed grand fir ( Abies concolor ) forests in Idaho, USA. Flycatchers selected territories with greater cover of deciduous vegetation in two different height strata (1–2 and 3–4 m) and reduced cover of conifers less than 4 cm dbh compared to what was available. While flycatchers selected habitat characteristics at the territory scale, model selection results did not support any associations between vegetation features and territory success. Territory success had weak positive associations, for a given territory size, with conspecific density, although the relationship was highly variable. An interaction between territory size and density was not supported. These results are consistent with the view that avian breeding habitat selection occurs at multiple scales, and that the nest site scale may explain more of the variance in reproductive success than larger scales. Our results suggest that operational management of vegetation features, which often occurs at the stand scale, may not influence variation in critical demographic metrics. Increasing total shrub cover of commonly used plant species should benefit the dusky flycatcher, as well as other shrub-nesting forest birds, but stand-level habitat alterations alone cannot be relied upon to increase reproductive success, an important component of population change.

Elevated landslide rates in forested landscapes can adversely impact aquatic habitat and water quality and remove and/or degrade soil resources required for forest regeneration. As a result, understanding the associations between management actions, natural factors, and landslide rates is important information needed for land managers. An unusual and powerful storm in early December, 2007, caused record flooding and thousands of landslides across southwest Washington and northwest Oregon, USA, and provided a rare opportunity to examine the effects of both natural factors and forest management practices on landslide density. Landslide inventory data were collected from both aerial photos and systematic field surveys to provide a broad survey database that was used to develop estimates of landslide density and to examine associations between landslide density, precipitation, topography, and forest stand age across a 152,000 ha forested landscape in the Willapa Hills, Washington. We estimated the probability of detecting landslides on aerial photos for six strata defined by forest stand age and a broad range of rainfall intensity, expressed as percent of the 100-year, 24-h, maximum rainfall. Key findings are that landslide detection probability decreased with increasing stand age, but was similar across rainfall intensities. The overall fraction of field-detected landslides that were not detected on 1:12,000-scale aerial photos was 39%. Very few landslides occurred in the 0–100% of 100-year rainfall category, regardless of stand age or slope gradient class. At higher rainfall intensities, significantly higher landslide densities occurred on steep slopes (>70% gradient) compared to lower gradient slopes, as expected. Above ∼150% of 100-year rainfall, the density of landslides was ∼2–3 times larger in the 0–5 and 6–10 year stand age categories than in the 11–20, 21–30, 31–40, and 41+ categories. The effect of stand age was strongest at the highest rainfall intensities. Our results demonstrate that ground-based landslide inventory data are required in order to correct for detection bias from aerial photos, develop reasonable estimates of landslide density across environmental gradients such as rainfall magnitude and topography, and make unbiased interpretations of relationships between forest management associations and landslide occurrence.

We examined the association of temporal and spatial factors with nest survival of Western Bluebirds (Sialia mexicana) nesting in tree cavities in ponderosa pine (Pinus ponderosa) forests along the east slope of the Cascade Mountains, Washington. All study areas were managed for timber production through planned harvests or postfire salvage logging. Bluebirds laid a mean clutch of 5.3 ± 0.1 (SE) eggs (n = 131), and successful nests fledged an average of 4.5 ± 0.2 young (n = 85). Using a model-selection framework, we found that nest survival was a function of clutch size and treatment and that there was a quadratic effect of nest age. Daily survival rates decreased after the onset of incubation, then increased through the nestling period, and were higher for clutches with ≥5 eggs and in stands that were burned and salvaged. Survivorship over the entire period for clutches (n = 131 nests) with ≤4, 5, and ≥6 eggs was 0.39 (95% CI: 0.11, 0.65), 0.61 (95% CI: 0.34, 0.80), and 0.71 (95% CI: 0.46, 0.85)...