In recent decades, dry ponderosa pine (Pinus ponderosa)-dominated forests of the eastern Cascades have experienced a dramatic increase in large, high-severity wildfires resulting in significant damage to natural resources. However, relatively little is known about long-term trends in postglacial fire activity in these forests. The purpose of this study was to reconstruct the fire and vegetation history of the Doheney Lake watershed, located in north-central Washington, using macroscopic charcoal and pollen analysis of a ca. 12,330-year-long lake sediment record. The results illustrate that regional climatic change, as well as climatically-controlled vegetation shifts, were the primary drivers of fire activity during much of the postglacial period. In particular, the establishment of the modern forest between ca. 7500 and 6000 cal yr BP due to cooler and moister conditions led to greater amounts of burnable biomass and generally higher levels of fire activity. The study results also suggest that greater interannual climate variability linked to drought may have played a role in the highly variable fire activity during much of the past 6,000 years. Additionally, it is likely that Indigenous cultural burning contributed to the fire activity at the site prior to Euro-American settlement, in particular during the past 4,000 years. Since ca. 125 cal yr BP (1825 CE), an almost complete absence of fire has allowed for the encroachment of shade-tolerant trees and has resulted in the potential for catastrophic wildfire, like that experienced at the site in 2015.

Riparian zones have unique microclimates that support distinct assemblages of aquatic and terrestrial species, which in recent decades have resulted in a regulatory emphasis on riparian protections. However, an understanding of the drivers of riparian microclimate is still lacking. This study examined drivers of variability in summer air temperature and vapor pressure deficit in the riparian zones of 10 drainage basins (31 to 789 ha) on the western Olympic Peninsula, Washington. Model selection analysis was used to explore hypotheses about the influences of 3 types of drivers on microclimate: regional climate gradients, proximity to stream, and solar radiation. Proximity to stream had the strongest influence on microclimate; the air became warmer and drier with increasing distance from the stream and with increasing steepness of the stream valley slope. Basins at lower elevations (range = 28 to 362 m) had cooler, more humid microclimates, a pattern attributed to marine influence. Variation in microclimate was also associated with variation in solar exposure, modeled as a function of topography. Testing of canopy closure influence on microclimate was hindered by uniformly high canopy closure across the study area (87 to 98%) as a result of unmanaged, primarily second-growth stream buffers. Each of the microclimate drivers identified in this study was a function of topography, across a range of scales. By understanding these relationships between topographic variation and riparian microclimate, managers and researchers will be able to more accurately and efficiently delineate the extent of riparian microclimate influence.

Beargrass (Xerophyllum tenax), an evergreen perennial herb of the northern Rocky Mountains, Pacific Northwest, and northern California, is used in Native American basketry and commercial floral greens. We studied beargrass size and biomass responses to crown removal by clipping or burning over three years in a coast Douglas-fir (Pseudotsuga menziesii var. menziesii) woodland with variable shrub cover in the southeastern Olympic Peninsula of Washington State. Clipping forested plants resulted in 28% mortality, mostly from smaller plants growing under 26% more total cover than the surviving plants; however, only 3% of completely crown-scorched open-grown plants died. Three years after treatment, crown width of surviving plants was only 61% of the pre-treatment size for clipped plants, compared to 88% for completely crown-scorched plants. Regression analyses indicated that the percentage of crown scorch accounted for only 16% and 27% of crown width and foliar height variation, respectively, one year post-burn, decreasing to 10% and 19% at three years post-burn. During the three years after burning, percentage flowering increased linearly to 64% of plants. Three years post-burn, foliar browse was higher on crown-scorched than on non-crown-scorched plants. Although shade tolerant, long-term survival of lowland beargrass is likely limited by combined competition from shrubs and trees. Stand density management is needed to maintain healthy, reproducing populations in the lowlands of western Washington.

Quantifying overwinter mass loss in bats is important for understanding hibernation energetics, habitat conservation, and the ability of bats to persist with novel pathogens. Townsend's big-eared bat (Corynorhinus townsendii) is a species of conservation concern. Little is known about overwinter mass loss of this bat in western North America. We conducted a retrospective analysis to quantify overwinter mass loss of 362 females and males during 1987 and 1988 in 5 caves in an important area for the conservation of this bat in western North America. Although body mass of 13 females in cave C62 averaged 1.1 g heavier than 12 females in cave C54 when captured in October, all those females recaptured in March lost similar percentages of body mass (x̄ = 22.6%) over winter. In cave C27, body mass of 6 females averaged 2.6 g heavier than 8 males when captured in October. Those females and males recaptured in March lost similar percentages of body mass (x̄ = 19.1%) over winter. In caves C27 and C54, mass of 96 male bats decreased by a mean of 21.1% between October and March. Across all five study caves, mass of 227 female bats decreased by a mean of 23.7% between October and March. Our results indicate that females are heavier than males when entering hibernation, and that females generally lose more mass than males during hibernation. Moreover, female bats entering hibernation in our study area weighed more than female bats of this species in other studies when entering hibernation. Our data provide researchers in western North America with mass loss estimates for female and male Townsend's big-eared bats.

We attempted to determine whether electrofishing removal estimates or single-pass snorkeling was a more reliable method for Oregon Department of Fish and Wildlife (ODFW) monitoring of juvenile coho salmon (Oncorhynchus kisutch) and steelhead (O. mykiss) abundance and occupancy trends. Based on 1997 to 2000 data, we assumed abundance estimates from the method that tracked more closely with parental abundance would better approximate true juvenile abundance. Parental abundance from spawning ground surveys and juvenile abundance metrics unique to each method were estimated from 2000 to 2004 and 2007 to 2008. Parental abundance did not explain the variation in juvenile abundance from either method (r² < 0.22), invalidating our assumption, but results had relevance for snorkel surveys used in ODFW monitoring. For both species, correlations between density (fish m^{2 -1}) and abundance (quantity, based on fish km^-1) estimates from snorkeling were weak (r < 0.379), but correlations between abundance estimates from both methods were strong (r > 0.846), implying abundance was more appropriate than density for ODFW monitoring. Neither method could sample all habitats, and annually variable proportions of coho salmon (15 to 47%) and steelhead (0 to 24%) abundance estimates obtained by electrofishing were in pools too shallow to meet the ODFW depth criterion for snorkeling. This resulted in lowering the criterion to ≥ 20 cm in 2010. The lower criterion, relative to original, has not shown differences in trends, but 30% more pools have been sampled, resulting in 23% higher abundance estimates with 10% proportionately smaller confidence intervals. These changes improved ODFW monitoring and related management decisions.

Aboveground pipelines (AGP) associated with in-situ oil sands may restrict mammal movement, potentially increasing extinction probability and decreasing reproductive success. Our 12-year study used winter track count techniques to assess the response of winter-active mammals to AGP in northern Alberta, Canada. The primary questions were: which species were most prone to movement obstruction by AGP, facilities or natural factor(s)?; and which factor exerted the strongest influence on crossing likelihood?

A total of 2,068 trails of 12 different species were observed. All species crossed more than half of the time. Focal species crossed on average 80% of the time. Crossing likelihood of white-tailed deer (Odocoileus virginianus), ermine (Mustela erminea), coyote (Canis latrans), lynx (Lynx canadensis), and fisher (Martes pennanti) were significantly influenced by predictors including pipeline height, pipeline corridor width, infrastructure age, vegetation type, and proximity to infrastructure. Deer and lynx crossing likelihood was positively affected by pipe height. Deer, coyote, and ermine crossing likelihood was positively affected by age of pipe. Fisher and deer crossing likelihood was negatively affected by pipeline corridor widths. Our investigations show that most species cross AGP with high crossing frequencies of pipe heights, ranging from 130 cm to 160 cm.

These findings are important for impact mitigation because of the scarcity of published studies of wildlife movement responses to AGP, our inclusion of small and mid-sized carnivores, and our investigation of multiple factors. We highlight mitigation and design improvements, effects of pipeline corridor widths, and challenges posed by coupling infrastructure with pipelines, serving to reduce movement barriers and fragmentation.

Natural disturbance shaped forest communities for millennia, but fire suppression and timber harvest declines have altered forest structure across the western United States, reducing the abundance of forage for ungulates. We evaluated quality and quantity of forage resources for lactating elk (Cervus canadensis) and their calves in relation to season, succession, and biogeoclimate, the latter indexed by potential vegetation (PV) zones, across 36,500 km² in Idaho's Clearwater and St. Joe River basins. In 0.2-ha macroplots (n = 359), we measured characteristics of forest overstory, biomass of current annual growth of undergrowth vegetation (kg ha^-1), and nutritional content of these plants. Using biomass, digestible energy (kJ g^-1), digestible protein (DP, g per100 g forage), and prior knowledge of elk diet selection and nutritional constraints, we developed 8 forage resource metrics. The greatest abundance of undergrowth vegetation (500 to 1,000 kg ha^-1) occurred during the first 20 years after stand-replacing disturbance and declined as the overstory closed in wetter PV zones. Digestible energy decreased, whereas DP increased as stands aged. Evidence of nutritional limitations for lactating elk increased markedly after mid-summer; early-seral, high-elevation spruce–fir forests on productive soils provided the best opportunity for lactating elk to satisfy their requirements in late summer. Our findings demonstrate the importance of disturbance regimes that maintain early-seral communities in mosaics with mid- and late-seral stages, and suggest that implementing stand-replacing disturbance in relatively moist forest zones at mid and high elevations provides the greatest improvement in forage resources for lactating elk and their calves in summer.

Leaf-litter-dwelling invertebrates serve an important role in ecosystem function by breaking down nutrients and potentially acting as indicators of habitat quality. However, this community is understudied due to difficulties related to sampling and taxonomic identification. To explore this community, we sampled leaf litter from the coastal and Cascade ranges of the Pacific Northwest of North America and searched > 200 samples for micro-invertebrates. We removed and photographed more than 400 invertebrate specimens, sequenced a portion of the mitochondrial gene cytochrome oxidase I (COI) for 60 samples, and used COI and the BLASTn database to identify invertebrates. Using these sequences and environmental data from the collection localities, we investigated the phylogeographic history of the two best-sampled species of microsnails, the toothless column snail (Columella edentula) and the conical spot snail (Punctum randolphii). Results suggest that populations of these species from the coastal and Cascade ranges may have survived in a single refugium during the Pleistocene glacial cycles and recolonized the coastal and Cascade ranges during the Holocene. Our results add to the knowledge of species responses to the Pleistocene glacial cycles in the Pacific Northwest and suggest that future studies should aim to increase representation of micro-invertebrates, perhaps using metabarcoding techniques.

Aboveground pipelines (AGP) associated with in-situ oil sands may restrict mammal movement, potentially increasing extinction probability and decreasing reproductive success. Our 12-year study used winter track count techniques to assess the response of winter-active mammals to AGP in northern Alberta, Canada. The primary questions were: which species were most prone to movement obstruction by AGP, facilities or natural factor(s)?; and which factor exerted the strongest influence on crossing likelihood?

A total of 2,068 trails of 12 different species were observed. All species crossed more than half of the time. Focal species crossed on average 80% of the time. Crossing likelihood of white-tailed deer (Odocoileus virginianus), ermine (Mustela erminea), coyote (Canis latrans), lynx (Lynx canadensis), and fisher (Martes pennanti) were significantly influenced by predictors including pipeline height, pipeline corridor width, infrastructure age, vegetation type, and proximity to infrastructure. Deer and lynx crossing likelihood was positively affected by pipe height. Deer, coyote, and ermine crossing likelihood was positively affected by age of pipe. Fisher and deer crossing likelihood was negatively affected by pipeline corridor widths. Our investigations show that most species cross AGP with high crossing frequencies of pipe heights, ranging from 130 cm to 160 cm.

These findings are important for impact mitigation because of the scarcity of published studies of wildlife movement responses to AGP, our inclusion of small and mid-sized carnivores, and our investigation of multiple factors. We highlight mitigation and design improvements, effects of pipeline corridor widths, and challenges posed by coupling infrastructure with pipelines, serving to reduce movement barriers and fragmentation.