Digital Commons Network^™

Housing Development Erodes Avian Community Structure In U.S. Protected Areas, Eric M. Wood, Anna M. Pidgeon, Volker C. Radeloff, David Helmers, Patrick D. Culbert, Nicholas S. Keuler, Curtis H. Flather

USDA Forest Service / UNL Faculty Publications

Protected areas are a cornerstone for biodiversity conservation, but they also provide amenities that attract housing development on inholdings and adjacent private lands. We explored how this development affects biodiversity within and near protected areas among six ecological regions throughout the United States. We quantified the effect of housing density within, at the boundary, and outside protected areas, and natural land cover within protected areas, on the proportional abundance and proportional richness of three avian guilds within protected areas. We developed three guilds from the North American Breeding Bird Survey, which included Species of Greatest Conservation Need, land cover affiliates …

Temporal Fluctuation Scaling In Populations And Communities, Michael Kalyuzhny, Yishai Schreiber, Rachel Chocron, Curtis H. Flather, Ronen Kadmon, David A. Kessler, Nadav M. Shnerb

USDA Forest Service / UNL Faculty Publications

Taylor’s law, one of the most widely accepted generalizations in ecology, states that the variance of a population abundance time series scales as a power law of its mean. Here we reexamine this law and the empirical evidence presented in support of it. Specifically, we show that the exponent generally depends on the length of the time series, and its value reflects the combined effect of many underlying mechanisms. Moreover, sampling errors alone, when presented on a double logarithmic scale, are sufficient to produce an apparent power law. This raises questions regarding the usefulness of Taylor’s law for understanding ecological …

Nitrogen And Carbon Dynamics In Prairie Vegetation Strips Across Topographical Gradients In Mixed Central Iowa Agroecosystems, Marlin Perez-Suarez, Michael J. Castellano, Randall Kolka, Heidi Asbjornsen, Matthew J. Helmers

USDA Forest Service / UNL Faculty Publications

Reductions of nitrogen (N) export from agricultural lands because of changes in specific N stocks andfluxes by incorporation of small amounts of prairie vegetation strips (PVS) are poorly understood. Theprimary objective of this study was to evaluate the effect of the presence and topographical position of PVSon soil and plant carbon (C) and N stocks relative to annual crop and native prairie vegetation. The studywas implemented within three small adjacent watersheds, treated with one of the following cover types:(1) 100% row-crop agriculture (CROP); (2) 20% prairie vegetation (PVS) distributed along the contouracross three topographical positions: upslope, sideslope and footslope position; …

Recovery Of Wolverines In The Western United States: Recent Extirpation And Recolonization Or Range Retraction And Expansion?, Kevin S. Mckelvey, Keith B. Aubry, Neil J. Anderson, Anthony P. Clevenger, Jeffrey P. Copeland, Kimberley S. Heinemeyer, Robert M. Iman, John R. Squires, John S. Waller, Kristine L. Pilgrim, Michael K. Schwartz

USDA Forest Service / UNL Faculty Publications

Wolverines were greatly reduced in number and possibly extirpated from the contiguous United States (U.S.) by the early 1900s. Wolverines currently occupy much of their historical range in Washington, Idaho, Montana, and Wyoming, but are absent from Utah and only single individuals are known to occur in California and Colorado. In response, the translocation of wolverines to California and Colorado is being considered. If wolverines are to be reintroduced, managers must identify appropriate source populations based on the genetic affinities of historical and modern wolverine populations. We amplified the mitochondrial control region of 13 museum specimens dating from the late …

Performance Of Species Richness Estimators Across Assemblage Types And Survey Parameters, Gordon C. Reese, Kenneth R. Wilson, Curtis H. Flather

USDA Forest Service / UNL Faculty Publications

Aim A raw count of the species encountered across surveys usually underestimates species richness. Statistical estimators are often less biased. Nonparametric estimators of species richness are widely considered the least biased, but no particular estimator has consistently performed best. This is partly a function of estimators responding differently to assemblage-level factors and survey design parameters. Our objective was to evaluate the performance of raw counts and nonparametric estimators of species richness across various assemblages and with different survey designs.

Location We used both simulated and published field data.

Methods We evaluated the bias, precision and accuracy of raw counts and …

A New Metric For Quantifying Burn Severity: The Relativized Burn Ratio, Sean A. Parks, Gregory K. Dillon, Carol Miller

USDA Forest Service / UNL Faculty Publications

Satellite-inferred burn severity data have become increasingly popular over the last decade for management and research purposes. These data typically quantify spectral change between pre-and post-fire satellite images (usually Landsat). There is an active debate regarding which of the two main equations, the delta normalized burn ratio (dNBR) and its relativized form (RdNBR), is most suitable for quantifying burn severity; each has its critics. In this study, we propose and evaluate a new Landsat-based burn severity metric, the relativized burn ratio (RBR), that provides an alternative to dNBR and RdNBR. For 18 fires in the western US, we compared the …