Long-term Integrated Assessments

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Statement of the ProblemThe rate and magnitude of ecosystem responses to climatic warming, land-use change, and alterations of major biogeochemical cycles at the Earth’s surface are variable and uncertain, ranging from gradual to abrupt, from moderate to profound. The least understood and least predictable responses—those that are both abrupt and profound—are perhaps those of greatest importance to natural resource managers. Recent examples of such responses include ongoing, drought-induced tree mortality on millions of hectares of forest in New Mexico, Arizona, and southern California; increases in area burned by severe wildfires in the western United States during the late 1980s to the first years of the 21st century; and exceedance of thresholds for eutrophication from atmospheric deposition. In all cases, ecosystem thresholds were quickly exceeded, leading to large and often unexpected changes that will have long-term consequences for protected areas. 

ObjetivesProgram element and goal: Terrestrial, Freshwater, and Marine Ecosystems, Goal 3 - Develop indexes of ecosystem sensitivity to change and vulnerability to potential stressors, and tools to predict ecosystem responses to environmental change. Objectives for this program are to observe, conduct research, and synthesize knowledge gained about the function of ecosystems experiencing changes in climate, land use, and biogeochemical cycling. Specific goals are to address (1) how climatic variability and change, alterations in N and C cycles, and land use change are likely to affect spatial and temporal patterns of ecological disturbance, ecosystem processes, and biogeochemical cycles; (2) how changing climate, disturbance, and biogeochemistry are likely to affect the composition, structure, and productivity of terrestrial and aquatic vegetation; and (3) which mountain and arctic resources and ecosystems are likely to be most sensitive/vulnerable to future climatic or biogeochemical change, and what are the possible management responses.

Strategy and Approachhe Integrated Assessments Project incorporates and supports long-term monitoring, experimental studies, ecological and physical modeling, paleoecological reconstructions, remote sensing, and spatial surveys of similar processes. Tasks will be conducted by USGS scientists, their students and collaborators, and stakeholders where appropriate. The approach will be one of rigorous science at all stages, culminating in professional publications or graduate degrees, and knowledge transfer to stakeholders and decision-makers.

Relevance and ImpaceHumankind is one of the two or three major driving environmental forces on Earth today. Over the past several decades we have come to a global awareness of societal ability to affect major Earth system functions, including cycles of water, nutrients, and even climate. Our information on the consequences to both natural ecosystems and human-dominated systems has grown commensurately with our understanding of the human role in changing Earth processes. There is a good chance that some of the changes now occurring due to human actions are irrevocable, launching the Earth into excursions in biogeochemical and water cycling never seen before in the four billion year history of the planet. Society relies completely on natural ecosystem functions for economic and social well-being, and very life support. Integrated Assessments are tools to gather, evaluate, and synthesize information that is important to society and land managers. Thay can include physical and ecosystem research, economic and social science inputs, and collaborative efforts between scientists and decision makers.