Organization: Department of Agriculture (USDA)

Research Title: Agriculture and Rangeland Global Change

Funding Level (millions of dollars):

FY94	10.4
FY95	11.3
FY96	11.7

Committee on Environment and Natural Resources (CENR) Component:
(a) Subcommittee: Global Change Research Subcommittee (100%)
(b) Environmental Issue: Large-scale changes in land use, including deforestation, acidification, ecosystem migration (100%)
(c) Research Activity: System structure and function: Understanding (100%)

Organizational Component:
ARS National Program Staff
Bldg. 005, BARC-W
Beltsville, MD 20705

Point of Contact:
Jan van Schilfgaarde
Phone: 301-504-7987
E-Mail: a03adanrnps@attnmail.com

Research Goals:
To assess the impact of global change on agricultural and rangeland ecosystems and impact of management practices on global change. To provide scientific information to support wise decisions on agricultural policy and management in the face of current uncertainty surrounding global change issues.

Research Description:
Research emphasizes four main areas as follows:

• Assessment of biogeochemical cycling and partitioning of carbon, nitrogen, and other nutrients between agricultural and rangeland systems and the atmosphere. Research is focused on: (1) sequestering and release of carbon in terrestrial pools and its interaction with the atmosphere, (2) carbon, nitrogen, and other nutrient cycles as they are influenced by anthropogenic activities, and (3) exchange of carbon dioxide, methane, and N-containing gases between terrestrial ecosystems and the atmosphere including observation of interannual variation of these exchanges.
  
• Understanding of the hydrologic processes and the interactions between snow accumulation and melt, soil moisture and freezing, distribution of precipitation, evapotranspiration, groundwater recharge and stream flow.
  
• Addresses the critical problem of scale in modeling terrestrial hydrologic and atmospheric processes and their interactions at point, watershed, and regional scales (1 square m to 1000 square km) as well as at the mesoscale (greater than 1000 square km).
  
• Development of a suite of quantitative simulation models for predicting responses of the major agronomic crops and managed ecosystems to ensure a continued abundant supply of food and fiber. To enhance this program, the multi-agency Terrestrial Ecosystem Regional Research and Analysis (TERRA) Laboratory will aggregate models from the Ecosystem Modeling, Biogeochemical Dynamics, and Climate and Hydrologic Systems elements to provide input to holistic Earth systems models required for further development of Global Change Models (GCMs). As GCMs improve in their ability to predict regional climate, TERRA will disaggregate the GCMs results to provide realistic scenarios for analyses of effects of global climate change on terrestrial ecosystems. TERRA was initiated in FY92 by USGS of DOI and ARS, FS, and SCS of USDA with the intention that it should become a neutral, broadly-based institution to develop land models and analyses for the terrestrial component of the U.S. Global Change Research Program (USGCRP).

Program Interfaces:
The research is linked with USDA agencies (FS, CSRS, and SCS) and with other Committee on Environment and Natural Resources (CENR) agencies as opportunities present themselves. Benefits will primarily be scientific information on which to develop policies and aid decision making at local, regional, and national scales involving the impact of climate and global change on the sustainability of food and fiber supplies and the health of the natural resource base. The ramifications of climate and global change on the agricultural and rangeland production systems make it imperative that the program be linked across most of the ARS research program. This is particularly true for areas such IPM, plant and animal genetics and breeding, water and nutrient use efficiency, and field and crop management systems.

Program Milestones:
Results provide inputs to process models being concurrently developed from experimentally measured gas flux and nutrient cycling data. These models contribute toward the goal of providing global fluxes of gases from terrestrial systems integrated over scales consistent with Global processes by GCM's. Linkages between individual plant, field, watershed scale models with regional scale models are planned for completion at the end of FY 1996. Modular linkages to the GCM's will be completed in FY 1998. Research will improve the accuracy of deterministic hydrologic models through the use of fundamental knowledge of hydrologic processes, new weather generation techniques incorporating elevation and spatial dependence of climate variables, El Niño-Southern Oscillation, and other effects, and new technology including remote sensing, geographic information systems, and digital elevation data. Model improvements are accomplished by coupling results from additional field research and experiments with new technologies with new modeling approaches, and expanding cooperative efforts with other federal agencies. One such effort with the SCS is the modification of the NLEAP model to evaluate best management practices of N based upon estimation of N₂O production which will begin in FY 1995 and be completed by FY 1998.

Policy Payoffs:
The research benefits all of society through application of research results to insure food and fiber production for the Nation on a sustainable basis. The results are an integral part of several databases used in formulating farm policy and details of agricultural transfer and support systems.