Photo: Cameron Aldridge, Colorado State University

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2013-3009

February 2013

Capabilities 

The Ecosystem Dynamics Branch of the Fort Collins Science Center 

offers an interdisciplinary team of talented and creative scientists with expertise in biology, botany, ecology, geology, biogeochemistry, physical sciences, 

geographic information systems (GIS), and remote-sensing, for tackling 

complex questions about natural resources. As demand for natural resources 

increases, the issues facing natural resource managers, planners, policy makers, industry, and private landowners are increasing in spatial and temporal 

scope, often involving entire regions, multiple jurisdictions, and long timeframes. Needs for addressing these issues include (1) a better understanding 

of biotic and abiotic ecosystem components and their complex interactions; 

(2) the ability to easily monitor, assess, and visualize the spatially complex 

movements of animals, plants, water, and elements across highly variable 

landscapes; and (3) the techniques for accurately predicting both immediate 

and long-term responses of system components to natural and human-caused 

change. The overall objectives of our research are to provide the knowledge, 

tools, and techniques needed by the U.S. Department of the Interior, state 

agencies, and other stakeholders in their endeavors to meet the demand for 

natural resources while conserving biodiversity and ecosystem services.

Ecosystem Dynamics scientists use field and laboratory research, data 

assimilation, and ecological modeling to understand ecosystem patterns, trends, and mechanistic processes. This information is used to predict the outcomes of changes imposed on species, habitats, landscapes, and climate across spatiotemporal 

scales. The products we develop include conceptual models to illustrate system structure and processes; regional baseline and 

integrated assessments; predictive spatial and mathematical models; literature syntheses; and frameworks or protocols for 

improved ecosystem monitoring, adaptive management, and program evaluation. The descriptions below provide snapshots of 

our three research emphases, followed by descriptions of select current projects.

FORT COLLINS SCIENCE CENTER

Ecosystem Dynamics Branch

Interdisciplinary Research for Addressing Complex Natural Resource 

Issues across Landscapes and Time

Photo: Steve Germaine, U.S. Geological Survey

Screen capture from an interactive map viewer 

showing oil and gas well density.

Energy Development and Changing Land Uses

Applied research and integrated regional assessments emphasize spatially 

explicit analyses of ecosystem components affected by energy development and 

land-use change in the western United States. Topics include sagebrush-steppe 

ecology; sagebrush habitat assessments; 

the effects of human activities (including energy development, transportation, and recreation) on habitats and 

wildlife behavior; habitat fragmentation 

and migration corridors; and technical 

assistance development for managers and 

decision makers.
Ecosystem Responses to Climate Change and Atmospheric Deposition

Research on Federal trust lands, especially in the mountains of western national parks and forests, 

addresses long-term ecosystem dynamics associated with climate change and atmospheric deposition of pollutants such as nitrogen. Studies include ecosystem biogeochemistry, nitrogen deposition, forest dieback, and 

assessment of forest biomes ranging from the Arctic to the desert Southwest. Our scientists are collaborating 

with researchers from around the world to describe and document global patterns of climate-induced forest 

dieback and the effects of atmospheric deposition on mountain ecosystems.

Selected Projects

Energy and Land Use—

Research and Technical Assistance

Exploration and development of domestic energy 

resources have become national priorities, yet the direct 

and indirect effects of energy development on surrounding 

ecosystems remain poorly understood. This poses a challenge 

for natural resource managers who must balance priorities 

that include maintaining healthy rangelands and wildlife 

habitats while providing for resource development and multiple public uses. In collaboration with other Fort Collins Science Center branches, several other USGS science centers, 

and partners from Federal, state, and local agencies, we are 

conducting interdisciplinary research to provide the information, techniques, and tools that resource managers and other 

stakeholders need to address these issues at regional levels 

in the western United States. This work contributes directly 

to the Wyoming Landscape Conservation Initiative, a longterm, landscape-scale 

science collaboration to ensure full 

consideration of and 

adaptive management for Wyoming’s 

wildlife and habitats 

as land-use pressures increase. Our 

energy and land-use 

work also involves 

(1) assessing and 

developing innovative tools for monitoring sagebrush 

habitat conditions; (2) developing targeted research and monitoring plans or frameworks; (3) identifying and assessing 

the ecological impacts of energy development, grazing, fire, 

roads and traffic, and climate change on sagebrush, aspen, 

and mountain shrubland ecosystems and species; (4) refining 

scientific understanding of sage-grouse population dynamics 

and genetics, pygmy rabbit demography and habitat use, and 

raptor habitat use; and (5) developing predictive models and 

maps that address management priorities.

Western Mountain Ecosystem Responses to 

Climate Change

The Ecosystem Dynamics Branch is participating in the 

Western Mountain Initiative, a cooperative effort to understand and predict the sensitivities, thresholds, resistance, 

and resilience of western mountain ecosystems to climatic 

variability and change. Our scientists are helping to develop 

comparative analyses of hydrological, ecological, and disturbance responses of watersheds in select mountain regions 

in Colorado, New Mexico, Montana, Oregon, Washington, 

and California to better understand current climate variability and predict future climate changes. Additionally, we are 

(1) continuing long-term ecological research and monitoring 

of the Loch Vale Watershed in Rocky Mountain National 

Park, Colo.; (2) studying the processes involved and the 

geographic extent of biogeochemical changes to headwaters ecosystems of the western United States in response to 

glacial melting and rock weathering; (3) conducting workshops for public land managers to help them develop and 

implement resource management measures that promote 

ecosystem resilience to climate change and reduce the risk of 

undesirable environmental outcomes; (4) continuing longterm ecological research and monitoring of ecohydrological 

responses in a semiarid watershed, as well as vegetation 

Photo: Steve Germaine, U.S. Geological Survey and tree growth along elevational gradients, in Bandelier 

Herbivore-Ecosystem Interactions

Data from these studies help inform management decisions regarding ungulates on public lands, typically in large, jurisdictionally complex 

landscapes. Recent work involves investigations on the effects of herd size 

and movements of elk, bison, and wild horses on various ecosystem components. Specifically, scientific efforts include (1) quantifying interactions 

among herbivores, plants, and soils; (2) determining the effects of ungulate 

herbivory on ecosystem processes and vegetation communities; (3) testing 

survey techniques for more accurate population estimates; and (4) evaluating 

contraceptive methods for managing wild horse populations. Photos: Bull elk, Gary Zahm, U.S. Fish and Wildlife Service; 

Elk herd, Kate Schoenecker, U.S. Geological Survey
National Monument, N. Mex.; 

(5) clarifying centennial- to 

millennial-length shifts in past 

vegetation and fire regimes; 

(6) elucidating responses of fire 

to short-term climatic variation; 

(7) determining long- and shortterm climatic controls of tree 

mortality, including thresholds 

for die-off; (8) documenting 

rapid and extensive climateinduced vegetation mortality, 

including global patterns of 

massive forest dieback; (9) determining the effects of climatic 

variability, fire, and land use on watershed runoff and erosion 

processes; and (10) supporting hydroecological model development as a tool for evaluating our understanding of the processes 

listed above and projecting future conditions under various 

climate-change scenarios. Our scientists also served as lead 

authors on several recent reports to the U.S. Congress by the 

U.S. Climate Change Research Program and the Subcommittee 

on Global Change Research.

Ecological Effects of Nitrogen and Sulfur Deposition

Disruption of the global nitrogen cycle is a major global 

change affecting ecosystems and the services they provide for 

society. We seek to understand the processes and fate of reactive nitrogen that is deposited on protected ecosystems, such as 

those in national parks and preserves. Five major approaches 

are routinely used to address questions about how excess reactive nitrogen influences biodiversity, nutrient cycling, water 

quality, and aquatic ecosystems: (1) long-term monitoring 

(especially in Loch Vale Watershed, Rocky Mountain National 

Park, Colo.), (2) field and laboratory experiments, (3) spatial 

comparisons, (4) paleoecological reconstructions of past conditions, and (5) ecosystem modeling. Results of the research and 

synthesis have been used to inform international policy dialogue 

for the Convention on Biological Diversity and the Convention on Long-Range Transboundary Air Pollution. At a national 

level, this work is helping to set critical loads, or thresholds, 

below which there are no discernable effects from atmospheric 

nitrogen deposition for lakes in the United States. We also 

provide state-of-the-art modeling on how climate change and 

nitrogen deposition interact to influence mountain ecosystems. 

The cumulative body of 

knowledge generated from 

the Loch Vale Watershed 

has been used to set emissions reduction policy for 

the State of Colorado, and 

the success of that policy 

will be determined from 

measurements collected 

over the next 20 years 

from Rocky Mountain 

National Park.

Elk and Bison Grazing Ecology in Great Sand 

Dunes National Park and Preserve

Ecosystem Dynamics scientists are conducting studies 

on bison and elk in the Great Sand Dunes National Park 

and Preserve to determine population status and movements, the effects of herbivory, and suitable habitat and 

population potential in the park and surrounding lands. 

Scientists are using these data to develop an elk and bison 

grazing model that treats grazing as a significant natural 

ecological process and incorporates protection of sensitive 

native-plant communities. Our scientists are using the study results to 

develop a predictive managementplanning model based on several 

potential management scenarios. 

These tools will provide direct 

support to park managers in developing and evaluating management 

alternatives for elk and bison.

Research for Management of 

America’s Wild Horses

Since the U.S. Congress passed The Wild FreeRoaming Horses and Burros Act of 1971, natural resource 

managers have sought effective tools for managing these 

animals on Federal lands. Wild horse populations can grow 

at rates of 18–25 percent per year, because they are largely 

unchecked by natural predators. This unregulated growth 

can overtax vegetation and affect native wildlife populations. Ecosystem Dynamics scientists, in collaboration with 

the Bureau of Land Management, National Park Service, 

U.S. Department of Agriculture’s Animal and Plant Health 

Inspection Service, and Colorado State University, are conducting research on fertility control for limiting population 

growth in wild horses. This research focuses on the immunocontraceptive vaccine, porcine zona pellucida (PZP), 

and investigates its effect on fertility, as well as potential 

side-effects, such as injection-site reactions, behavior modifications, and the temporal distribution of births. Additional 

research is being conducted on GonaCon, the gonadotropin-releasing hormone vaccine, and an alternative form of 

PZP called SpayVac*. We are also evaluating aerial survey 

techniques for estimating population size of wild horses 

and related species. This research focuses on synergistically combining several 

known abundance estimation techniques, such as 

simultaneous double-count, 

mark-resight, distance 

sampling, and sightability 

bias correction modeling, 

to alleviate shortfalls of the 

individual techniques and 

generate better estimates 

of population size with 

scientifically defensible 

confidence intervals.

Photo: Steve Hillebrand, 

U.S. Fish and Wildlife Service

Photo: Carrie English, U.S. Geological Survey

Photo: Jared Heath, Colorado State University

*Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Photo: Jared Heath, Colorado State University
Raptors and Wind Development—Developing ScienceBased Tools for Conservation Planning

Potential declines in Wyoming raptor 

populations have generated concern within 

the U.S. Fish and Wildlife Service (FWS), 

the agency responsible for ensuring compliance with the Migratory Bird Treaty Act 

and the Bald and Golden Eagle Protection 

Act. Also of concern are the limitations of 

standard FWS measures currently recommended for mitigating effects of development activities on raptors, because they 

(1) are applied during only one season, 

(2) focus only on known nest or roost sites, 

and (3) do not account for foraging areas, 

unknown roost and nest sites, and movement corridors. To address these limitations, priority raptor habitats 

in Wyoming need to be identified. The primary goal of this project 

is to develop a quantitative, predictive model that describes the 

relationship between available habitat and habitat use for four raptor 

species in Wyoming: Golden Eagle, Ferruginous Hawk, Northern 

Harrier, and Prairie Falcon. Our project will result in models and 

maps that identify priority raptor habitat areas. In turn, these products will promote effective raptor conservation by facilitating the 

prioritization of locations for strategic, focused conservation efforts. 

If proven effective, the models and techniques may be expanded to 

identify priority raptor habitats in other regions.

Contact Information 

Zachary Bowen, Branch Chief, Ecosystem Dynamics

U.S. Geological Survey 

Fort Collins Science Center

2150 Centre Avenue, Building C 

Fort Collins, Colorado 80526-8118

Tel. 970.226.9218 Fax 970.226.9230 

bowenz@usgs.gov

Learn more about FORT science, products, 

and resources at http://www.fort.usgs.gov

Learn more about the Ecosystem Dynamics Branch 

at: http://www.fort.usgs.gov/ED/

Photo: Natasha Carr, U.S. Geological Survey

Photo: Cameron Aldridge, 

Colorado State University

Staff

Ecosystem Dynamics research staff possess extensive education and experience in ecology, wildlife biology, 

botany, population ecology and dynamics, habitat and population modeling, climate change, natural and humancaused perturbations, biogeochemistry, geology, fire science, and spatial analysis. 

Branch Chief: Zachary Bowen, Ph.D., Supervisory Ecologist, bowenz@usgs.gov

Aldridge, Cameron, Ph.D., Scientist (Colorado State University contractor), 

 aldridgec@usgs.gov

Allen, Craig, Ph.D., Research Ecologist, craig_allen@usgs.gov

Anderson, Patrick, M.S., General Biologist, andersonpj@usgs.gov

Assal, Timothy, Ph.D. Candidate, Ecologist, assalt@usgs.gov

Baron, Jill, Ph.D., Research Ecologist, jill_baron@usgs.gov or jill@nrel.colostate.edu

Carr, Natasha, Ph.D., Ecologist, carrn@usgs.gov

Germaine, Stephen, M.S., Ecologist, germaines@usgs.gov

Hall, Edward, Ph.D., Research Biologist, ehall@usgs.gov

Manier, Daniel, Ph.D., Research Manager III (Cherokee Services Group contractor), 

 manierd@usgs.gov

Mask, Tracy, M.S. Candidate, Biological Science Technician, tmask@usgs.gov

McDougal, Robert, M.S., Geologist, rmcdougal@usgs.gov

Melcher, Cynthia, M.S., Wildlife Biologist, melcherc@usgs.gov

Ouren, Douglas, M.S., Physical Scientist, ourend@usgs.gov

Roelle, James, Ph.D., Supervisory Fish and Wildlife Biologist, roelleb@usgs.gov

Saher, Joanne, M.S., Scientist (Colorado State University contractor), saherj@usgs.gov

Schell, Spencer, B.S., Ecologist, schells@usgs.gov

Schoenecker, Kathryn, Ph.D. Candidate, Ecologist, schoeneckerk@usgs.gov

Tack, Jason, Ph.D. Candidate, Biologist, jtack@usgs.gov

Wann, Gregory, Ph.D. Candidate, Science Technician, wanng@usgs.gov

Zeigenfuss, Linda, M.S., Wildlife Biologist, linda_zeigenfuss@usgs.gov

Front page banner photos	MFGUUPSJHIU
: Gregor Auble, U.S. Geological Survey; Tracy Mask, U.S. Geological Survey; and Kate Schoenecker, U.S. Geological Survey