Publications
Filter Total Items: 1990
The state of amphibians in the United States
More than 25 years ago, scientists began to identify unexplained declines in amphibian populations around the world. Much has been learned since then, but amphibian declines have not abated and the interactions among the various threats to amphibians are not clear. Amphibian decline is a problem of local, national, and international scope that can affect ecosystem function, biodiversity, and comme
Authors
E. Muths, M.J. Adams, E.H.C. Grant, D. Miller, P. S. Corn, L.C. Ball
Variability in expression of anadromy by female Oncorhynchus mykiss within a river network
We described and predicted spatial variation in marine migration (anadromy) of female Oncorhynchus mykiss in the John Day River watershed, Oregon. We collected 149 juvenile O. mykiss across 72 sites and identified locations used by anadromous females by assigning maternal origin (anadromous versus non-anadromous) to each juvenile. These assignments used comparisons of strontium to calcium ratios i
Authors
Justin S. Mills, Jason B. Dunham, Gordon H. Reeves, John R. McMillan, Christian E. Zimmerman, Chris E. Jordan
Burial increases seed longevity of two Artemisia tridentata (Asteraceae) subspecies
Premise of the study: Seed longevity and persistence in soil seed banks may be especially important for population persistence in ecosystems where opportunities for seedling establishment and disturbance are unpredictable. The fire regime, an important driver of population dynamics in sagebrush steppe ecosystems, has been altered by exotic annual grass invasion. Soil seed banks may play an active
Authors
Upekala C. Wijayratne, David A. Pyke
Individual condition and stream temperature influence early maturation of rainbow and steelhead trout, ncorhynchus mykiss
Alternative male phenotypes in salmonine fishes arise from individuals that mature as larger and older anadromous marine-migrants or as smaller and younger freshwater residents. To better understand the processes influencing the expression of these phenotypes we examined the influences of growth in length (fork length) and whole body lipid content in rainbow trout (Oncorhynchus mykiss). Fish were
Authors
John R. McMillan, Jason B. Dunham, Gordon H. Reeves, Justin S. Mills, Chris E. Jordan
Linking physical monitoring to coho and Chinook salmon populations in the Redwood Creek Watershed, California—Summary of May 3–4, 2012 Workshop
On Thursday, May 3, 2012, a science workshop was held at the Redwood National and State Parks (RNSP) office in Arcata, California, with researchers and resource managers working in RNSP to share data and expert opinions concerning salmon populations and habitat in the Redwood Creek watershed. The focus of the workshop was to discuss how best to synthesize physical and biological data related to th
Authors
Mary Ann Madej, Alicia Torregrosa, Andrea Woodward
Recent population trends of mountain goats in the Olympic Mountains, Washington
Mountain goats (Oreamnos americanus) were introduced in Washington's Olympic Mountains during the 1920s. The population subsequently increased in numbers and expanded in range, leading to concerns by the 1970s over the potential effects of non-native mountain goats on high-elevation plant communities in Olympic National Park. The National Park Service (NPS) transplanted mountain goats from the Oly
Authors
Kurt J. Jenkins, Patricia J. Happe, Katherine F. Beirne, Roger A. Hoffman, Paul C. Griffin, William T. Baccus, John Fieberg
N2-fixing red alder indirectly accelerates ecosystem nitrogen cycling
Symbiotic N2-fixing tree species can accelerate ecosystem N dynamics through decomposition via direct pathways by producing readily decomposed leaf litter and increasing N supply to decomposers, as well as via indirect pathways by increasing tissue and detrital N in non-fixing vegetation. To evaluate the relative importance of these pathways, we compared three-year decomposition and N dynamics of
Authors
Steven S. Perakis, Joselin J. Matkins, David E. Hibbs
Radio telemetry equipment and applications for carnivores
Radio-telemetry was not included in the first comprehensive manual of wildlife research techniques (Mosby 1960) because the first published papers were about physiological wildlife telemetry (LeMunyan et al. 1959) and because research using telemetry in field ecology was just being initiated (Marshall et al. 1962; Cochran and Lord 1963). Among the first uses of telemetry to study wildlife, however
Authors
Mark R. Fuller, Todd K. Fuller
Increasing synchrony of high temperature and low flow in western North American streams: double trouble for coldwater biota?
Flow and temperature are strongly linked environmental factors driving ecosystem processes in streams. Stream temperature maxima (Tmax_w) and stream flow minima (Qmin) can create periods of stress for aquatic organisms. In mountainous areas, such as western North America, recent shifts toward an earlier spring peak flow and decreases in low flow during summer/fall have been reported. We hypothesiz
Authors
Ivan Arismendi, Mohammad Safeeq, Sherri L. Johnson, Jason B. Dunham, Roy Haggerty
Summary of bird-survey and banding results at W.L. Finley National Wildlife Refuge, 1998-2008
With some of the best remaining examples of oak habitats in the Willamette Valley, the Willamette Valley National Wildlife Refuge Complex (WVNWRC) has been implementing restoration efforts to reverse the successional trend towards Douglas-fir and maple that is threatening existing oak woodlands. The restoration work has been considered a model for other public and private efforts within the Willam
Authors
Joan Hagar
Nitrogen limitation, 15N tracer retention, and growth response in intact and Bromus tectorum-invaded Artemisia tridentata ssp. wyomingensis communities
Annual grass invasion into shrub-dominated ecosystems is associated with changes in nutrient cycling that may alter nitrogen (N) limitation and retention. Carbon (C) applications that reduce plant-available N have been suggested to give native perennial vegetation a competitive advantage over exotic annual grasses, but plant community and N retention responses to C addition remain poorly understoo
Authors
Dana L. Witwicki, Paul S. Doescher, David A. Pyke, Nicole M. DeCrappeo, Steven S. Perakis
Arthropod prey for riparian associated birds in headwater forests of the Oregon Coast Range
Headwater riparian areas occupy a large proportion of the land base in Pacific Northwest forests, and thus are ecologically and economically important. Although a primary goal of management along small headwater streams is the protection of aquatic resources, streamside habitat also is important for many terrestrial wildlife species. However, mechanisms underlying the riparian associations of some
Authors
Joan C. Hagar, Judith Li, Janel Sobota, Stephanie Jenkins