Effects of Climatic Variability and Land Use on American Drylands

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Project Overview

Statement of Problem

Objectives

Strategy

Project Tasks and Activities

• Task 1: Interactions among geology, biogeochemistry, and ecological biology - past, current, and future
• Task 2: Dust - climatic, geomorphic, and hydrologic factors and societal effects
• Task 3: Sand-dune dynamics - history and processes of eolian sand movement in American drylands
• Task 4: Valley Fever - determination of geological/ecological occurrence models for Coccidioides Immitis
• Task 5: Land-use change and water quality in the Tsezhin Bii' region, Navajo Nation
• Task 6: Sediment dynamics in dryland rivers - relations to climate, groundwater, and land use
• Measuring, modeling, and forecasting change

Statement of Problem

Arid and semi-arid lands compose about one half of the U.S. and are among the Nation's most sensitive regions to climatic variability and land-use practices (ref 1). Combinations of natural factors (such as short-term climatic variability) and vastly expanding population, especially in the Southwest, are placing unprecedented pressures on our dry landscapes and their ecological resources. The existing and potential impacts make American drylands a national priority for understanding environmental change and its effects on both human dominated and natural systems. In particular, interactions among land management, societal adjustment, and local to regional planning require contributions and collaborations across many arenas of natural and social sciences (refs 2, 3, 4). Examples of key problems include physical impacts of drought and wet periods, ecosystem health (e.g., invasive plant species), human health, water quality and quantity, carbon cycling, as well as fire frequency and impacts (refs 1, 5). This project addresses the urgent need to understand and measure physical landscape change and its influence on ecosystems and the human communities that depend on ecological services such as water, productivity, and landscape stability. On the scale of ecosystems to physiographic regions of American drylands, we will develop new understanding of interactions among physical, biogeochemical, and human systems, and responses of these systems to forcing from climate and demographic change. With this understanding, we will forecast expectable, near-term changes in physical and ecological landscapes. We will provide information, forecasts, and educational materials to federal, state, local, and Native American agencies and communities, for their land-use planning, management of resources, and protection of human health.

Objectives

1. Examine interactions among geologic, hydrologic, biologic, and atmospheric processes in drylands to (i) understand contemporary physical and ecological landscapes; (ii) determine how physical and ecological processes interact to influence ecosystem dynamics, including plant invasions; and (iii) document how sediment (soil) erosion and deposition by wind and water over time is affected by climatic variability and by geologic, physiographic, and land-use setting.
1. Understand landscape responses to changes in climate over different time scales (past seasons, decades, centuries, millennia) in terms of dust emission and deposition, sand-dune activity, and fluvial erosion & deposition.
2. Understand landscape responses to land uses in terms of dust emission and deposition, sand-dune activity, and fluvial erosion and deposition and evaluate these responses in a framework of climatic variability and how geologic properties influence ecosystem resilience.
3. Understand how geologic substrates and processes control vegetation distributions, plant invasions, soil moisture, water infiltration rates, plant-nutrient status.
4. Understand interactions among aeolian, fluvial, lacustrine, and groundwater processes in drylands that have produced or eroded surficial deposits; determine ages of these deposits, the environmental/climatic conditions under which they formed, and respective vulnerabilities of these deposits to future erosion.
2. Measure land surface and ecological changes in response to climate and human activity in several ecologically sensitive dryland areas, as a basis for (a) understanding surficial processes and (b) developing geologic and ecological response models.
3. Forecast the responses of dry landscapes to climatic variability using newly developed and established geologic, hydrologic, and biogeochemical models of landscape processes.
1. Forecast geo-ecological responses to environmental change from interactions among geologic substrates, hydrology, climate, land use, and biogeochemical cycling of carbon, nitrogen, phosphorus, and other nutrients (e.g., pathways of cheatgrass invasion).
2. Forecast future dust emissions and reactivated sand dunes by linking process-response models to empirical models and regional climate models.
4. Elucidate the effects of environmental change (natural and human-related) on human health, with focus on emissions of dust containing toxic metals and on the airborne transmission of the infectious agent for Valley Fever.
5. Provide information and educational materials to agencies and communities, for their land-use planning, management of resources, and protection of human health:
1. Federal land-management agencies (National Park Service, BLM, BoR, USDA)
2. Dept. of Defense
3. Health and environment agencies (e.g., EPA, CDC)
4. States and communities
5. Native American nations

Strategy and Approach

The approach involves: (1) examining past records of physical, biological, and landscape changes in response to climatic and human-mediated forces; (2) measuring these changes today, including emerging human health risks; (3) comparing observations of modern processes with the records of past changes; and (4) integrating the knowledge gained from (1), (2), and (3) to provide forecasts of future land-surface and ecological change under likely climatic and demographic conditions for time scales relevant for land-use decisions.

1. Determine and describe the physical characteristics of ecologically important geologic settings in American drylands:
1. Document chemical and mineralogic composition, texture, morphology, and origin of surficial deposits
2. Understand links among plant-community distributions, geologic setting and substrates, nutrient distributions, climatic variability, and land use
2. Measure climate and soil erosion at geologically dynamic sites having different land-use histories.
3. Measure plant physiological responses, biogeochemical fluxes, and soil moisture/water infiltration with respect to geologic substrates, climatic variability, and land-use history.
4. Measure changes in physical and ecological landscapes using remote sensing methods to assess vulnerability to climate and land use.
5. Evaluate the effects of geologic processes and change on selected ecosystems of American drylands.
6. Develop landscape models that link soil/weathering geochemistry, sediment erosion and deposition, hydrology, and ecosystem dynamics.
7. Develop geologic process models that describe dust emission and fluvial erosion in response to geologic, climatic, and land-use conditions.
8. Develop methods to detect and measure dust emission, determine dust transport pathways, recognize past and modern dust sources, and identify aeolian dust in soil and its role in ecosystem dynamics.
9. Develop, test, and apply wind-erosion and climate models for forecasts of dust emission under future climate.
10. Develop new methods to assess hazards of airborne dust to human and animal health.
11. Combine methods in mineralogy and reflection spectroscopy to determine the effects of dust on melting rates of snowpack.
12. Evaluate the potential for dust-borne infections of Valley Fever based on the wind-erosion vulnerability of soils that contain the fungus responsible for the disease.
13. Develop capability for regional climate modeling for forecasting wind erosion.

Project strengths and collaborations exist within and outside USGS in: (1) ecology for research on ecosystems, invasive species, ecosystem modeling; (2) climate and vegetation modeling; (3) paleoclimate and land-surface response to climate change; (4) aeolian processes and deposits; (5) dust-emission observation and modeling; (6) medical geology to assess health hazards from dust; (7) geologic and vegetation mapping to link surfaces with plant communities over large areas; (8) geochemical landscape study; (9) medicine for studies of Valley Fever; (10) air quality on federal lands; (11) snow-pack sampling and modeling for timing of snow melt; (12) application of results to management of public lands.

We are closely aligned with projects funded by Global Change Program (Climate, Land Use, and Environmental Sensitivity; Eolian History of North America; Navajo Nation Studies; Mojave Paleohydrology; Western Lake Catchment Systems) and with many other projects and Programs (e.g., Geochemical Landscapes; Earth Materials & Human Health; Salton Sea Ecosystem Restoration; SEM Microprobe Laboratories; Recovery and Vulnerability of Desert Ecosystems; Surficial Geologic mapping in the Southwest; U.S.-Mexico Environmental Health Initiative; Great Basin Integrated Landscape Monitoring; Land Cover Applications, Landscape Dynamics, and Global Change, working with each of the other USGS Disciplines).

Relevance and Impact

We address problems in: (1) conditions of dry landscapes, their vulnerability to degradation (e.g., cheatgrass invasion, soil loss), and their potential for recovery to sustain desirable functions; (2) sources, amounts, and composition of wind-eroded dust, including dust containing toxic metals or fungal spores, that cause disease in humans; (3) impacts of sand-dune activation on society; (4) effects of climatic variability (e.g., drought, flooding events) and land-use practices on arid landscapes, ecology, and communities (refs 1-7). We aim to anticipate societally important changes and effects that are likely to occur over the next few seasons, years, and decades.

Our research on how geological and ecological processes are linked to ecosystem dynamics is at the heart of our capability to interact with land managers. We have built strong influence in, and are commonly consulted by, the NPS, BLM, other agencies (local governments, public health services, non-governmental organizations) for management of lands and anticipating environmental change. We provide information about key national issues, such as plant invasion; carbon-storage; expected ecologic change; dust emission; effects of drought and flood damage related to erosion and alluviation in urban, grazed, and protected settings. We produce definitive results on urban flooding and erosion in Las Vegas Valley that carry lessons for land-use planning in other desert communities. We have responded to DoD requests, some urgent, with respect to landscape health and sustainability of training grounds, dust-emitting conditions of helicopter landing zones, and geologic conditions of global dust sources that affect operations. We have conducted laboratory measurements on dust from a war zone bearing on malfunctioning of weaponry.

The completed work on soil habitats for the pathogen causing Valley Fever, combined with new methods in mapping vulnerability to wind erosion, may lead to forecasts of disease outbreaks via atmospheric transport of biologic contaminants, with bearing on National security.

New methods developed by the project and adopted by other researchers include imaging and monitoring dryland surfaces and wind erosion, identification of aeolian dust in soil, detection of invasive plant species from space, development of new physical process models, as well as modeling of soil habitat for a pathogen. Some of our new imaging techniques have been adopted by other USGS projects (San Francisco Bay; Hawaiian coral reefs; Colorado River). Our studies also bear critically on interpreting results from the North American Landscape Geochemistry project (Minerals).

In 2010, we began to study effects of dust on the timing and rate of snow melt, linking mineralogy, texture, and reflection spectroscopy analyses to snow-melt modeling by collaborators. This issue bears on water-resource management, especially in the Colorado River system providing for >30 M inhabitants and critical agricultural areas in the Southwest. Our work in the American West can be applied to the problem in other mountain ranges (e.g., Himalayas).

We maintain strong associations with other drylands researchers and a variety of the earth-science research communities to advance understanding of issues facing the Nation's drylands and related problems of desertification (ref 8).

The project adheres to goals of USGS Science Strategy, USGCRP (ref 2), and the 2002 Climate Change Research Science Program (CCSP) and Initiative (CCRI; ref 3). Project activities contribute to USGS Science Strategy (ref 9) categories:

• Understanding Ecosystems and Predicting Ecosystem Change: Ensuring the Nation's Economic and Environmental Future
• Climate Variability and Change: Clarifying the Record and Assessing Consequences
• The Role of Environment and Wildlife in Human Health: A System that Identifies Environmental Risk to Public Health in America

References Cited

1. Meredith, R., Liverman, D., Bales, R., and Patterson, M., 1998, Climate Variability and Change in the Southwest: Impacts, Information Needs, and Issues for Policymaking: Udall Center for Studies in Public Policy, Univ. of Arizona, 81 p.

2. U.S. Global Change Research Program, 2002, Our Changing Planet: The FY2002 U.S. Global Change Research Program: National Science and Technology Council, 100 p.

3. U.S. Federal Administration, 2002, The U.S. Climate Change Research Initiative (CCRI): Survey of Research Strategies to Reduce Scientific Uncertainties: Dept of Commerce (Draft)

4. Intergovernmental Panel on Climate Change, 2001, Climate Change 2001: Impacts, Adaptation, and Vulnerability: Cambridge, Cambridge Univ. Press, 98 p.

5. National Assessment Synthesis Team, 2000, Climate Change Impacts on the United States: The Potential Consequences of Climate Variability and Change: Cambridge, Cambridge Univ. Press

6. Intergovernmental Panel on Climate Change, 2001, Climate Change 2001: The Scientific Basis: Cambridge, Cambridge Univ. Press, 98 p.

7. Woodward, F.I., 1992, Global Climate Change: The Ecological Consequences: London, Academic Press, 337 p.

8. Dregne, H. E. 1986. Desertification of arid lands. In Physics of desertification, ed. F. El-Baz and M. H. A. Hassan. Dordrecht, The Netherlands: Martinus, Nijhoff.

9. U.S. Geological Survey, 2007, Facing Tomorrow's Challenges-U.S. Geological Survey Science in the Decade 2007-2017: U.S. Geological Survey Circular 1309, 70 p.