Wild horse populations on western ranges can increase rapidly, resulting in the need for the Bureau of Land Management (BLM) to remove animals in order to protect the habitat that horses share with numerous other species. As an alternative to removals, BLM has sought to develop a long-term, perhaps even permanent, contraceptive to aid in reducing population growth rates. With long-term (perhaps even permanent) efficacy of contraception, however, comes increased concern about the genetic health of populations and about the potential for local extirpation. We used simulation modeling to examine the potential demographic and genetic consequences of applying a mare sterilant to wild horse populations. Using the VORTEX software package, we modeled the potential effects of a sterilant on 70 simulated populations having different initial sizes (7 values), growth rates (5 values), and genetic diversity (2 values). For each population, we varied the treatment rate of mares from 0 to 100 percent in increments of 10 percent. For each combination of these treatment levels, we ran 100 stochastic simulations, and we present the results in the form of tables and graphs showing mean population size after 20 years, mean number of removals after 20 years, mean probability of extirpation after 50 years, and mean heterozygosity after 50 years. By choosing one or two combinations of initial population size, population growth rate, and genetic diversity that best represent a herd of interest, a manager can assess the likely effects of a contraceptive program by examining the output tables and graphs representing the selected conditions.
An integrated model of environmental drivers of growth, carbohydrate balance, and mortality of Pinus ponderosa forests in the Southern Rocky Mountains
Climate-induced tree mortality is an increasing concern for forest managers around the world. We used a coupled hydrologic and ecosystem carbon cycling model to assess temperature and precipitation impacts on productivity and survival of ponderosa pine (Pinus ponderosa). Model predictions were evaluated using observations of productivity and survival for three ponderosa pine stands located across an 800 m elevation gradient in the southern Rocky Mountains, USA, during a 10-year period that ended in a severe drought and extensive tree mortality at the lowest elevation site. We demonstrate the utility of a relatively simple representation of declines in non-structural carbohydrate (NSC) as an approach for estimating patterns of ponderosa pine vulnerability to drought and the likelihood of survival along an elevation gradient. We assess the sensitivity of simulated net primary production, NSC storage dynamics, and mortality to site climate and soil characteristics as well as uncertainty in the allocation of carbon to the NSC pool. For a fairly wide set of assumptions, the model estimates captured elevational gradients and temporal patterns in growth and biomass. Model results that best predict mortality risk also yield productivity, leaf area, and biomass estimates that are qualitatively consistent with observations across the sites. Using this constrained set of parameters, we found that productivity and likelihood of survival were equally dependent on elevation-driven variation in temperature and precipitation. Our results demonstrate the potential for a coupled hydrology-ecosystem carbon cycling model that includes a simple model of NSC dynamics to predict drought-related mortality. Given that increases in temperature and in the frequency and severity of drought are predicted for a broad range of ponderosa pine and other western North America conifer forest habitats, the model potentially has broad utility for assessing ecosystem vulnerabilities.
Modeling mountain pine beetle disturbance in Glacier National Park using multiple lines of evidence
Assal, T.J., J. Sibold, and R. Reich
Updated Date (text):
Parent Publication Title:
Vegetation Dynamics II, Association of American Geographers 2013 Annual Meeting, Los Angeles, CA. April 13, 2013
Energy development is rapidly escalating in resource-rich Wyoming, and with it the risks posed to raptor populations. These risks are of increasing concern to the U.S. Fish and Wildlife Service, which is responsible for protecting the persistence of protected species, including raptors. In support of a Federal mandate to protect trust species and the wind energy industry’s need to find suitable sites on which to build wind farms, scientists at the USGS Fort Collins Science Center (FORT) and their partners are conducting research to help reduce impacts to raptor species from wind energy operations. Potential impacts include collision with the turbine blades and habitat disruption and disturbance from construction and operations. This feature describes a science-based tool—a quantitative predictive model—being developed and tested by FORT scientists to potentially avoid or reduce such impacts. This tool will provide industry and resource managers with the biological basis for decisions related to sustainably siting wind turbines in a way that also conserves important habitats for nesting golden eagles. Because of the availability of comprehensive data on nesting sites, golden eagles in Wyoming are the prototype species (and location) for the first phase of this investigation.
Development of a North American Bat Population Monitoring and Modeling Program
Loeb, S., J. Coleman, L. Ellison, P. Cryan, T. Rodhouse, T. Ingersoll, and R. Ewing
Updated Date (text):
Parent Publication Title:
North American Society for Bat Research (NASBR), 42nd Annual Symposium on Bat Research, San Juan, Puerto Rico, 24-27 October, 2012
Public Review Release—Feedback on this report will be accepted through August 1, 2012. To provide comments, please click below, then go to section marked "Offer your comments on our draft strategies": http://www.usgs.gov/start_with_science/
Core Science Systems is a new mission of the U.S. Geological Survey (USGS) that grew out of the 2007 Science Strategy, “Facing Tomorrow’s Challenges: U.S. Geological Survey Science in the Decade 2007–2017.” This report describes the vision for this USGS mission and outlines a strategy for Core Science Systems to facilitate integrated characterization and understanding of the complex earth system. The vision and suggested actions are bold and far-reaching, describing a conceptual model and framework to enhance the ability of USGS to bring its core strengths to bear on pressing societal problems through data integration and scientific synthesis across the breadth of science.
The context of this report is inspired by a direction set forth in the 2007 Science Strategy. Specifically, ecosystem-based approaches provide the underpinnings for essentially all science themes that define the USGS. Every point on earth falls within a specific ecosystem where data, other information assets, and the expertise of USGS and its many partners can be employed to quantitatively understand how that ecosystem functions and how it responds to natural and anthropogenic disturbances. Every benefit society obtains from the planet—food, water, raw materials to build infrastructure, homes and automobiles, fuel to heat homes and cities, and many others, are derived from or effect ecosystems.
The vision for Core Science Systems builds on core strengths of the USGS in characterizing and understanding complex earth and biological systems through research, modeling, mapping, and the production of high quality data on the nation’s natural resource infrastructure. Together, these research activities provide a foundation for ecosystem-based approaches through geologic mapping, topographic mapping, and biodiversity mapping. The vision describes a framework founded on these core mapping strengths that makes it easier for USGS scientists to discover critical information, share and publish results, and identify potential collaborations that transcend all USGS missions. The framework is designed to improve the efficiency of scientific work within USGS by establishing a means to preserve and recall data for future applications, organizing existing scientific knowledge and data to facilitate new use of older information, and establishing a future workflow that naturally integrates new data, applications, and other science products to make it easier and more efficient to conduct interdisciplinary research over time. Given the increasing need for integrated data and interdisciplinary approaches to solve modern problems, leadership by the Core Science Systems mission will facilitate problem solving by all USGS missions in ways not formerly possible...
Suitability modeling and the location of utility-scale solar power plants in the southwestern United States
As states and regions have begun prioritizing renewable energy at the legislative level, solar energy has started to play a noticeably larger role in the energy portfolio of certain regions in the United States. Decision making concerning the siting of new solar facilities can be complicated, and GIS-based suitability modeling is often employed to determine ideal candidate sites. These suitability models seek to evaluate a comprehensive set of relevant criteria (such as insolation values, topography, access, land designation status, etc.), often at different weights, to produce a classified map of all potential sites that will facilitate decisions of site location...
Consequences of cannibalism and competition for food in a smallmouth bass population: An individual-based modeling study