Coweeta Long Term Ecological Research (LTER) Program is the centerpiece of a cooperative
effort between the University of Georgia and the USDA Forest Service Coweeta Hydrologic Laboratory, funded by the National Science Foundation since 1980. Major university cooperators include Virginia Polytechnic Institute and State University, Duke University, University of Minnesota, Mars Hill College, University of Wisconsin - Madison, and Portland State University. The Coweeta LTER Program encompasses a broad array of cooperative studies averaging 30 projects annually with about 55 graduate and undergraduate students and senior investigators. Process-level studies at Coweeta are linked with reference watersheds for evaluating ecosystem responses to disturbance.

The goal of the Coweeta LTER Program is to integrate individual research efforts into a holistic concept of watershed response across a range of time and spatial scales.

Coweeta LTER research combines short-term (five years or less) with long-term (decades) studies
on the responses of forested watersheds and streams to natural and human-induced disturbances. Although much of the research takes place within the Coweeta basin, several studies are conducted in other ecosystems in the region such as the interdisciplinary study on the causes and consequences of land use change in the southern Appalachians. Current research emphases include: continuing analyses of long-term hydrology, nutrient cycling, and productivity responses to management practices and natural disturbances (drought, flood, wind, insects); the cumulative effects of land-use practices on water quality; assessment of prescribed burning effects on the forest environment; interdisciplinary, inter-institutional implementation of ecosystem management on national forests; interrelationships of forest litter on stream productivity, decomposition, and trophic levels; impacts of atmospheric deposition on forest ecosystems; physiological studies of forest carbon balance and competition; and biodiversity.

Disturbance as an Organizing Theme
The southern Appalachian mountains are highly erodable and subject to multiple disturbances. Natural disturbances include hurricanes, floods, droughts, insect and disease outbreaks, ice storms, windthrow, and fire whereas anthropogenic disturbances include two centuries of impacts from steep mountain agriculture, grazing, forest clearing, and rapidly expanding residential and recreational use. Streams and forests have
exhibited an ability to partially return to their original state following disturbance. Current research focuses on identifying and quantifying these long-term changes in stream and forest ecosystem structure and function.

Diversity
Southern Appalachian landscapes exhibit high species diversity relative to many regions in North America. For example, the southern Appalachians contain 345 fish species, and the Tennessee River has the highest fish diversity of any river in the United States. Favorable environmental conditions including moderate temperatures, high precipitation (1800 to 2300 mm year -1) distributed evenly throughout the year, deep soils, and continuously flowing streams provide ample resource availability
across the complex landscape.


Terrestrial research is organized across the landscape with elevations ranging from 678 to 1592 m along the complex environmental gradients created by abiotic factors including elevation, aspect, precipitation, and temperature. Terrestrial processes including productivity, decomposition, soil nitrogen mineralization, photosynthesis, respiration, herbivory, seed rain, and seedling demography are quantified along this gradient. This gradient approach allows the functional relationships between variables to be defined and also allows the variables to be extrapolated to the larger landscape of the southern Appalachians.



The exchange of water, sediment, carbon, and nutrients between terrestrial and aquatic ecosystems is regulated by riparian zones. More than 73 km of upland streams exist in the 2185 ha of forest at Coweeta Hydrologic Laboratory. Therefore, riparian zones constitute a large proportion of the landscape.

Most riparian zones in these forested areas are dominated by Rhododendron maximum, an evergreen shrub. This keystone species (i.e., it has a greater role than its coverage would suggest) is slow growing, but has increased in coverage since fire suppression began in the 1920s. To determine the effect of Rhododendron in riparian areas, soil water, groundwater, nutrients, and litter fluxes are being quantified in areas where Rhododendron has been removed, and compared to untreated control areas during a multi-year study.



Aquatic research at Coweeta is facilitated by the detailed characterization of hydrologic regimes in small (3 ha) to large (760 ha) watersheds, some of which have been monitored since 1934.  These catchments provide one of the longest continuous hydrologic records in the world.

Aquatic research has investigated the influences of water chemistry, decomposition, organic detritus dynamics, and stream bed morphology on the relationship of stream primary and secondary productivity, trophic levels, micro- and macro-arthropod populations, and fish abundance and diversity.



Socioeconomic research in our southern Appalachian regionalization study area has quantified both the past (1950s) and current land use patterns for selected study areas. These Geographic Information System (GIS) layers are the bases for both anthropological and economic studies to determine the causes and consequences of observed land use patterns and changes over time. In addition, our socioeconomic studies are predicting land use patterns for the year 2030, which will provide likely future scenarios depicting the consequences of present patterns of population growth and land use change. Current trends indicate that the largest land use shift is from marginal agricultural land back to successional forested areas, but increased home construction is causing the forested areas to become more fragmented.

Regional aquatic studies in the greater 56,000 km 2 southern Appalachian study area quantify the impact that historical and current land use has on the productivity and diversity of stream fauna. Even though terrestrial vegetation may have recovered from disturbance in most of a watershed, stream fauna reflect past disturbance conditions from as many as 50 years earlier, suggesting that recovery time may be greater for stream than terrestrial ecosystems.