The widespread declines of native bull trout (Salvelinus confluentus) and westslope cutthroat trout (Oncorhynchus clarkii lewisi) populations prompted researchers to investigate factors influencing their distribution and status in western Glacier National Park, Montana. We evaluated the association of a suite of abiotic factors (stream width, elevation, gradient, large woody debris density, pool density, August mean stream temperature, reach surface area) with the occurrence (presence or absence) of bull trout and westslope cutthroat trout in 79 stream reaches in five sub-drainages containing glacial lakes. We modeled the occurrence of each species using logistic regression and evaluated competing models using an information theoretic approach. Westslope cutthroat trout were widely distributed (47 of 79 reaches), and there appeared to be no restrictions on their distribution other than physical barriers. Westslope cutthroat trout were most commonly found in relatively warm reaches downstream of lakes and in headwater reaches with large amounts of large woody debris and abundant pools. By contrast, bull trout were infrequently detected (10 of 79 reaches), with 7 of the 10 (70%) detections in sub-drainages that have not been compromised by non-native lake trout (S. namaycush). Bull trout were most often found in cold, low-gradient reaches upstream of glacial lakes. Our results indicate that complex stream habitats in sub-drainages free of non-native species are important to the persistence of native salmonids in western Glacier National Park. Results from this study may help managers monitor and protect important habitats and populations, inform conservation and recovery programs, and guide non-native species suppression efforts in Glacier National Park and elsewhere.

Native prairie plant communities are among the most endangered habitats due to extensive agricultural use and exotic species invasion. Understanding how species composition, particularly of exotic species, varies with environment is essential for management and preservation of these communities. In semi-arid prairies, plant establishment is often heterogeneous across the landscape and depends on the patchy availability of resources across environmental gradients. We studied how soil geologic substrate, topography, and grazing history relate to patterns of native and exotic plant distribution in a semiarid Mima mound prairie in eastern Washington. We analyzed the relationship between native and exotic species richness and abundance on 61 Mima mounds in a prairie underlain by two types of soil geologic substrate (glacial alluvium and basalt) where half of each had been grazed recently. We found that exotic species richness and cover were lowest and native species cover was highest on mounds underlain by basalt bedrock that had experienced recent grazing; on sites underlain by glacial alluvium there was little difference between more and less recently grazed mounds. Moreover, we found that exotic abundance was greatest at the top of Mima mounds compared to the sides; the opposite was true for native species. Our findings indicate that geologic substrate and grazing history may interact to determine plant distribution in semi-arid prairie communities. This study demonstrates that land managers aiming to restore native plant communities need to consider the synergistic effects of multiple environmental factors in order to focus restoration funding and effort.

Pacific Northwest riparian forests occupy dynamic environments, host high biodiversity, and support important ecological services like nutrient storage/transformation, flood attenuation, and water quality protection. Lack of information on their historical condition and changes hinder effective ecosystem management. We combined archival records and contemporary field surveys to reconstruct historical riparian conditions and change in Hood Canal and the eastern Strait of Juan de Fuca, Washington. Historical riparian forest composition and structure varied by shoreline type and landform. Conifer species dominated all shoreline types, with hardwoods relatively abundant in estuaries and stream bottomlands. Older, more structurally diverse forests clustered in stream ravines, with the size of stream-riparian fir and redcedar dominants measuring 2.5 and 8 times larger than in upland stands, respectively. Over half (57.9%) of stream-riparian redcedar-spruce forest sites shifted to hardwood/mixed forest over the historical period, versus fir-hemlock, alder, and hardwood/mixed forest types which all showed ≤35.3% change. Classification and regression tree models highlighted historical forest type, elevation, and proximity to bottomlands as key predictors of vegetation change, with historical conifer sites in/near bottomlands two times more likely to undergo change than upland stands. Our findings provide spatially explicit historical context for ecosystem managers and modelers, and suggest new questions pertinent to riparian forest management.

Microclimate variables such as air temperature and relative humidity influence habitat conditions and ecological processes in riparian forests. The increased relative humidity levels within riparian areas are essential for many plant and wildlife species. Information about relative humidity patterns within riparian areas and adjacent uplands are necessary for the prescription of effective buffer widths. Relative humidity monitoring is more expensive than temperature monitoring due to greater sensor costs, and it is primarily conducted for research purposes. To make relative humidity monitoring in riparian areas more cost effective, we explored modeling relative humidity as a function of air temperature and other covariates using linear fixed and linear mixed effects models applied to two case studies. Localizing predictions for stream reaches using a linear mixed effects model or a linear fixed effects model with correction factor improved model predictions, especially when large variability among stream reaches was present. A minimum of three to five relative humidity measurements per stream reach seem sufficient to estimate the random stream reach effect or correction factor for the linear mixed and linear fixed effects models, respectively. Including covariates that describe distance to stream and canopy cover in addition to air temperature improved model performance. Although further model refinement is probably needed to allow detection of small changes in relative humidity associated with changes in stand structure from partial overstory removal, the models developed provide a means towards decreasing the costs of monitoring microclimates of importance to riparian area function.

The reproductive biology of the California floater (Anodonta californiensis), western ridged mussel (Gonidea angulata) and western pearlshell (Margaritifera falcata) was studied in the Middle Fork John Day River from May 2005 to July 2011. Anodonta californiensis was gravid from early May to late July. Mature A. californiensis glochidia were hooked, rust-colored, sub-triangulate, averaged 276 µm in length, and were similar in size to other glochidia of the genus Anodonta. Gravid G. angulata were found only in June. Mature G. angulata glochidia were hookless, white, sub-round, and averaged 171 µm in length, similar to the oval pigtoe (Pleurobema pyriforme). Margaritifera falcata were gravid in early May. Mature M. falcata glochidia were hookless, white, sub-round, and averaged 55 µm in length, a size and shape similar to the spectacle case (Cumberlandia monodonta). Anodonta californiensis glochidia were found attached to six wild-caught fish species from early June to late July. In contrast, G. angulata glochidia were found attached only to wild-caught sculpin (Cottus sp.) in late July. No M. falcata glochidia were observed on fish in the field. In laboratory experiments, speckled dace (Rhinichthys osculus) was a confirmed primary host and the longnose dace (R. cataractae), and margined sculpin (Cottus marginatus) served as unconfirmed primary hosts for A. californiensis. Margined and shorthead sculpin (C. confusus) were identified as unconfirmed primary hosts for G. angulata.