Print PageAgro-ecosystems are major components of the earth’s overall spectrum of ecosystems. Many are intensely managed and these systems are expected to expand to meet growing demands for food and biofuels. It is critical that these systems be managed to provide an array of essential ecosystem services while minimizing negative impacts. The USDA Agricultural Research Service (ARS) and Forest Service (FS) currently maintain a continental scale network of over 90 Benchmark Watersheds, Experimental Ranges and Forests, and associated/related research facilities that collect long-term physical, chemical, and biological data on agricultural sustainability, climate change, ecosystem services, and natural resource conservation at the watershed or landscape scale with data records from 5 to over 100 years. Eight of these sites are also LTER sites and several of 20 core NEON sites are proposed to be located with these USDA sites. USDA is currently seeking input from the academic and Federal research communities, and its customers and stakeholders, regarding the organization of a select number of these existing research sites into a more formally organized Long-Term Agro-ecosystem Research (LTAR) Network. To illustrate the value of these long-term, continentally distributed, observations we identified and analyzed data from 81 of the USDA sites with data records of more than 20 years measuring important ecosystem dynamics such as variations in vegetation, precipitation, climate, runoff, water quality and soil moisture.
Results/Conclusions
Through a series of examples, we illustrate how USDA long-term data have been used to understand key ecohydrological and agro-ecosystem issues, including (1) time lag between cause and effects, (2) critical thresholds and cyclic trends, (3) context of rare and extreme events and (4) mechanistic feedbacks for simulation modelling. Analyses of network-wide, long-term data from USDA experimental sites were also used to illustrate the potential for multi-year, multi-site ecohydrological research. Three areas of investigation were identified to best exploit the unique spatial distribution and long-term data of USDA experimental sites: convergence, cumulative synthesis and autocorrelation. This review underscored the need for continuous, interdisciplinary data records spanning more than 20 years across a wide range of ecosystems within and outside the conterminous USA to address major crosscutting problems facing ecohydrology and agro-ecosystem and further underscores the important need for a more formalized Long-Term Agro-ecosystem Research (LTAR) network for coordinated research in support of enhancing the sustainability of agro-ecological goods and services, including the production of agricultural commodities.
