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Publications

Below is a list of available NOROCK peer reviewed and published science. If you are in search of a specific publication and cannot find it below or through a search, please contact twojtowicz@usgs.gov.

Filter Total Items: 1192

Assessing climate change effects on mountain ecosystems using integrated models: A case study

Mountain systems are characterized by strong environmental gradients, rugged topography and extreme spatial heterogeneity in ecosystem structure and composition. Consequently, most mountainous areas have relatively high rates of endemism and biodiversity, and function as species refugia in many areas of the world. Mountains have long been recognized as critical entities in regional climatic and hy
Authors
Daniel B. Fagre, Steven W. Running, Robert E. Keane, David L. Peterson

Ecology of Florida black bears in the Okefenokee-Osceola ecosystem

The population status of the Florida black bear (Ursus americanus floridanus) is problematic within many portions of its range and its potential listing as a federally threatened species has been the subject of legal debate. We studied Florida black bears in 2 areas in the Okefenokee-Osceola ecosystem in southeast Georgia (i.e.,Okefenokee) and north Florida (i.e., Osceola) from 1995 to 1999 to eva
Authors
S. Dobey, D.V. Masters, B.K. Scheick, J. D. Clark, M.R. Pelton, M.E. Sunquist

Bait stations, hard mast, and black bear population growth in Great Smoky Mountains National Park

Bait-station surveys are used by wildlife managers as an index to American black bear (Ursus americanus) population abundance, but the relationship is not well established. Hard mast surveys are similarly used to assess annual black bear food availability which may affect mortality and natality rates. We used data collected in Great Smoky Mountains National Park (GSMNP) from 1989 to 2003 to determ
Authors
Joseph D. Clark, Frank T. van Manen, Michael R. Pelton

Topography and vegetation as predictors of snow water equivalent across the alpine treeline ecotone at Lee Ridge, Glacier National Park, Montana, U.S.A.

We derived and implemented two spatial models of May snow water equivalent (SWE) at Lee Ridge in Glacier National Park, Montana. We used the models to test the hypothesis that vegetation structure is a control on snow redistribution at the alpine treeline ecotone (ATE). The statistical models were derived using stepwise and “best” subsets regression techniques. The first model was derived from fie
Authors
C. A. Geddes, Daniel G. Brown, Daniel B. Fagre

Evaluating single-pass catch as a tool for identifying spatial pattern in fish distribution

We evaluate the efficacy of single-pass electrofishing without blocknets as a tool for collecting spatially continuous fish distribution data in headwater streams. We compare spatial patterns in abundance, sampling effort, and length-frequency distributions from single-pass sampling of coastal cutthroat trout (Oncorhynchus clarki clarki) to data obtained from a more precise multiple-pass removal e
Authors
Douglas S. Bateman, Robert E. Gresswell, Christian E. Torgersen

Spatial and temporal variability in the amount and source of dissolved organic carbon: Implications for ultraviolet exposure in amphibian habitats

The amount, chemical composition, and source of dissolved organic carbon (DOC), together with in situ ultraviolet (UV-B) attenuation, were measured at 1–2 week intervals throughout the summers of 1999, 2000, and 2001 at four sites in Rocky Mountain National Park (Colorado). Eight additional sites, four in Sequoia and Kings Canyon National Park/John Muir Wilderness (California) and four in Glacier
Authors
P. D. Brooks, C. M. O'Reilly, S. A. Diamond, K. Campbell, R. Knapp, D. Bradford, P. S. Corn, B. Hossack, K. Tonnessen

A simulation test of the effectiveness of several methods for error-checking non-invasive genetic data

Non-invasive genetic sampling (NGS) is becoming a popular tool for population estimation. However, multiple NGS studies have demonstrated that polymerase chain reaction (PCR) genotyping errors can bias demographic estimates. These errors can be detected by comprehensive data filters such as the multiple-tubes approach, but this approach is expensive and time consuming as it requires three to eight
Authors
David A. Roon, L.P. Waits, K.C. Kendall

Evaluating mixed samples as a source of error in non-invasive genetic studies using microsatellites

The use of noninvasive genetic sampling (NGS) for surveying wild populations is increasing rapidly. Currently, only a limited number of studies have evaluated potential biases associated with NGS. This paper evaluates the potential errors associated with analysing mixed samples drawn from multiple animals. Most NGS studies assume that mixed samples will be identified and removed during the genotyp
Authors
David A. Roon, M.E. Thomas, K.C. Kendall, L.P. Waits

Incisor wear and age in Yellowstone bison

Biologists commonly use tooth eruption and wear patterns or cementum annuli techniques to estimate age of ungulates. However, in some situations the accuracy or sampling procedures of either approach are undesirable. We investigated the progression of several quantitative measures of wear with age, using permanent first incisors from Yellowstone bison (Bison bison), and tested for differences betw
Authors
D.A. Christianson, P.J.P. Gogan, K.M. Podruzny, E.M. Olexa

A geostatistical approach for describing spatial pattern in stream networks

The shape and configuration of branched networks influence ecological patterns and processes. Recent investigations of network influences in riverine ecology stress the need to quantify spatial structure not only in a two-dimensional plane, but also in networks. An initial step in understanding data from stream networks is discerning non-random patterns along the network. On the other hand, data c
Authors
L.M. Ganio, C.E. Torgersen, R. E. Gresswell

Changing patterns in coastal cutthroat trout (Oncorhynchus clarki clarki) diet and prey in a gradient of deciduous canopies

We examined the influence of riparian vegetation patterns on coastal cutthroat trout Oncorhynchus clarki clarki diet and prey from the summer of 2001 through the spring of 2002. Benthic and drifting invertebrates, allochthonous prey, and fish diet were collected from deciduous, conifer, and mixed sections of three Oregon coastal watersheds. The nine sites were best characterized as a continuum of
Authors
N. Romero, R. E. Gresswell, J.L. Li

From the field: Brown bear habituation to people — Safety, risks, and benefits

Recently, brown bear (Ursus arctos) viewing has increased in coastal Alaska and British Columbia, as well as in interior areas such as Yellowstone National Park. Viewing is most often being done under conditions that offer acceptable safety to both people and bears. We analyze and comment on the underlying processes that lead brown bears to tolerate people at close range. Although habituation is a
Authors
Stephen Herrero, Tom Smith, Terry D. DeBruyn, Kerry Gunther, Colleen A. Matt