Treesearch

A common approach used to estimate landscape resistance involves comparing correlations of ecological and genetic distances calculated among individuals of a species. However, the location of sampled individuals may contain some degree of spatial uncertainty due to the natural variation of animals moving through their home range ormeasurement error in plant or animal locations. In this study, we evaluate the ways that spatial uncertainty, landscape characteristics, and genetic stochasticity interact to influence the strength and variability of conclusions about landscapegenetics relationshi...

Little is known about how variation in landscape mosaics affects genetic differentiation. The goal of this paper is to quantify the relative importance of habitat area and configuration, as well as the contrast in resistance between habitat and non-habitat, on genetic differentiation. We hypothesized that habitat configuration would be more influential than habitat area in influencing genetic differentiation. Population size is positively related to habitat area, and therefore habitat area should affect genetic drift, but not gene flow. In contrast, differential rates and patterns of gene...

Deer mice (Peromyscus maniculatus) are the main reservoir host for Sin Nombre virus, the primary etiologic agent of hantavirus pulmonary syndrome in North America. Sequential changes in weather and plant productivity (trophic cascades) have been noted as likely catalysts of deer mouse population irruptions, and monitoring and modeling of these phenomena may allow for development of early-warning systems for disease risk. Relationships among weather variables, satellite-derived vegetation productivity, and deer mouse populations were examined for a grassland site east of the Continental...

We examined the cultural, social, and economic aspects of livestock operations of ranchers who have Federal grazing permits (called permittees) on the Santa Fe and Carson National Forests of northern New Mexico. This study was an expansion of the 2003 pilot study and was designed to provide much-needed information concerning the culture and economic practices of the northern New Mexico region for USDA employees, policy makers, social science researchers, and the general public. The research focused on both the economic and noneconomic contributions of livestock ownership to local families...

An important first step in managing forest roads for improved water quality and aquatic habitat is the performance of an inventory. The Geomorphic Roads Analysis and Inventory Package (GRAIP) was developed as a tool for making a comprehensive inventory and analysis of the effects of forest roads on watersheds. This manual describes the data collection and process of a GRAIP road inventory study using GRAIP v. 1.0.8 and the field data dictionary INVENT 5.0. The GRAIP model uses field data collected with a GPS and a specific data dictionary using drop-down menus that is designed to be...

An important first step in managing forest roads for improved water quality and aquatic habitat is the performance of an inventory. The Geomorphic Roads Analysis and Inventory Package (GRAIP) was developed as a tool for making a comprehensive inventory and analysis of the effects of forest roads on watersheds. This manual describes the data analysis and process of a GRAIP road inventory study using GRAIP v. 1.0.8 and the field data dictionary INVENT 5.0.GRAIP uses field data collected with a GPS and a specific data dictionary that is imported into ArcGIS as shapefiles. The data are...

Climate scenarios offer one way to identify and examine the land management challenges posed by climate change. Selecting projections, however, requires careful consideration of the natural resources under study, and where and how they are sensitive to climate. Selection also depends on the robustness of different projections for the resources and geographic area of interest, and possibly on what climate projections are available for a region. Rather than a misguided attempt to identify the "most accurate" climate scenario, managers are strongly encouraged to explore variability through...

Down logs provide important ecosystem services in forests and affect surface fuel loads and fire behavior. Amounts and kinds of logs are influenced by factors such as forest type, disturbance regime, forest man-agement, and climate. To quantify potential short-term changes in log populations during a recent global- climate-change type drought, we sampled logs in mixed-conifer and ponderosa pine (Pinus ponderosa) forests in northern Arizona in 2004 and 2009 (n = 53 and 60 1-ha plots in mixed-conifer and ponderosa pine forests, respectively). Over this short time interval, density of logs,...

Sound forest policy and management decisions to mitigate rising atmospheric CO2 depend upon accurate methodologies to quantify forest carbon pools and fluxes over large tracts of land. LiDAR remote sensing is a rapidly evolving technology for quantifying aboveground biomass and thereby carbon pools; however, little work has evaluated the efficacy of repeat LiDAR measures for spatially monitoring aboveground carbon pools through time. Our study objective was therefore to evaluate the use of discrete return airborne LiDAR for quantifying biomass change and carbon flux from repeat field and...

The mechanisms for range expansion in invasive species depend on how genetic variation is structured in the introduced range. This study examined neutral genetic variation in the invasive annual grass Bromus tectorum in the Intermountain Western United States. Patterns of microsatellite (SSR) genotype distribution in this highly inbreeding species were used to make inferences about the roles of adaptively signifi cant genetic variation, broadly adapted generalist genotypes, and facultative outcrossing in the recent range expansion of B. tectorum in this region.