Treesearch

Landslides into valley bottoms can affect longitudinal profiles of rivers, thereby influencing landscape evolution through base-level changes. Large landslides can hinder river incision by temporarily damming rivers, but catastrophic failure of landslide dams may generate large floods that could promote incision. Dam stability therefore strongly modulates the effects of landslide dams and might be expected to vary among geologic settings. Here, we investigate the morphometry, stability, and effects on adjacent channel profiles of 17 former and current landslide dams in eastern Oregon. Data...

Batrachochytrium salamandrivorans (Bsal) is an emerging fungal pathogen that has caused recent die-offs of native salamanders in Europe and is known to be lethal to at least some North American species in laboratory trials [1]. Bsal appears to have originated in Asia, and may have been introduced by humans into wild populations in Europe through commercial trade of amphibians [1]. Since the first outbreaks of Bsal in the Netherlands, it has been the etiologic agent of mortality events in Belgium (wild) and Germany (captivity), and was recently found in imported salamanders in the United...

Sites containing winter browse species utilized by moose on the Copper River Delta of south-central Alaska were mechanically treated (hydraulic-axed) to counteract possible earthquake related increases in less-preferred forage species, and to measure treatment effects on biomass, height, nutritional quality (crude protein, lignin, and tannin), utilization, and snow burial on preferred (willow [Salix spp.]) and less-preferred forage species (sweetgale [Myrica gale], cottonwood [Populus trichocarpa], and alder [Alnus viridis sinuata]) within 3 winter scenarios (mild, moderate, and severe)....

Eelgrass (Zostera marina) is the dominant seagrass along the Pacific North American Coast, providing complex physical structure, high trophic productivity, and protection from predators (Phillips 1984; Simenstad 1994). Because of these multiple functions, many fish species and life stages use Eelgrass beds more than other nearshore habitat types (Dean and others 2000; Murphy and others 2000; Johnson and Thedinga 2005). Currently, there is growing evidence identifying nearshore habitats as places that may be regularly inhabitated by large-bodied fish, including sharks (Tobin and others...

Past studies have documented differences in epicuticular wax among several tree species but little attention has been paid to changes in accumulation of foliar wax that can occur during the year. We sampled current-year needles from the terminal shoots of Douglas-fir (Pseudotsuga menziesii var. menziesii) in late June/early July, late August and early November. Needles were sampled from two sites that differed in their climate and shoot phenology. Adaxial (upper), abaxial (lower) and cross-sectional surfaces were examined on scanning electron micrographs. Wax thickness increased significant...

Plant responses to ozone (O3) and water deficit (WD) are commonly observed, although less is known about their interaction. Stomatal conductance (gs) is both an impact of these stressors and a protective response to them. Stomatal closure reduces inward flux of O3 and outward flux of water. Stomatal measurements are generally obtained at midday when gas exchange is maximal, but these may not be adequate surrogates for stomatal responses observed at other times of day, nor for non-stomatal responses. Here, we find in Pima cotton that stomatal responses to O3 observed at midday do not...

Dam removal is reconnecting rivers, and lessons learned will help water-resource and river management, particularly as removals expand globally and choices become more challenging.

White-headed woodpeckers (Picoides albolarvatus) are important cavity excavators that recently have become the focus of much research because of concerns over population declines. Past studies have focused on nest site selection and survival but information is needed on factors influencing their space use when away from the nest. We examined space use by white-headed woodpeckers during the nesting (May–Jul) and post-nesting (Jul–Oct) periods and compared the role of environmental factors (e.g., landcover) and socio-demographic factors (e.g., age, breeding success) in home range size and...

Prevailing theory suggests that stream temperature warms asymptotically in a downstream direction, beginning at the temperature of the source in the headwaters and levelling off downstream as it converges to matchmeteorological conditions.However, there have been few empirical examples of longitudinal patterns of temperature in large rivers due to a paucity of data. We constructed longitudinal thermal profiles (temperature vs distance) for 53 rivers in the PacificNorthwest (USA) using an extensive data set of remotely sensed summertime river temperatures and classified each profile into...