Coweeta LTER

The complex interaction between projected changes in climate and land use across the 60,000 km2 Coweeta LTER study area led us to adopt a nested hierarchical framework to examine provisioning, regulating and preserving ecosystem processes and services. However, the research design gives recognition to how processes and services in southern Appalachia depend contextually on forces associated with the Piedmont Megapolitan Region (236,000 km2) in which it is imbedded. This larger region contains Atlanta and other major southeastern urban centers surrounding southern Appalachia. Sampling, experimental manipulations, and modeling are designed to capture interactions within a range of distinct landscapes reflecting the flowpaths, habitats, and human communities characteristic of southern Appalachia.

We work across a range of scales from coarse to fine consisting of (1) regional basins, (2) sub-basins, (3) headwater watersheds, and (4) hillslopes and riparian zones.

This flowpath network with intervening natural and built spaces extends upstream from the perennial stream system through transitional, intermittent and ephemeral phases terminating in unchannelized hillslopes. A critical aspect of the research is that study sites are co-located so that different groups of collaborating investigators can obtain complementary measures to produce comprehensive descriptions of local system status and dynamics. Hillslope and riparian zone responses are being characterized at a spatial resolution relevant to the targeted processes using observational and manipulative approaches. Socio-ecological gradients of sub-basins and headwater watersheds are being intensively sampled using instruments, observational, arms-length, and face-to-face procedures. Regional basin patterns and responses are being extensively sampled using direct measurements, remote sensing products, socioeconomic databases, and government sources. We synthesize and upscale observational and experimental research using a process-based approach designed to resolve cross-scale interactions among gradients in moisture, microclimate, settlement intensity, and regulatory environment.

The Coweeta LTER program consists of multi-scale process-oriented research on the consequences to the southern Appalachian socio-ecological system of the interaction between changing climate and land use. We expect landscapes in the southeastern U.S. to change profoundly in the next five decades as the socioeconomic factors driving the dramatic exurbanization of the past three decades persist, and the changes to the rates, frequencies, and intensities of important climatic factors occur. Climate and land use change will especially impact the rural and quasi-rural lands that still characterize much of southern Appalachia, which is both a ‘water tower’ to the Southeast and one of the most biodiverse temperate regions in the U.S. if not the world.

Our research program extends long-term measurements, field experiments and interdisciplinary modeling from small watershed studies to regional-scale analyses so as to account for increases in resource demand and competition from adjacent and more distant areas. Our focus is on the provisioning service of water quantity, the regulating service of water quality, and the supporting service of maintaining biodiversity. The overarching question that guides this research is: How will key ecosystem processes and the focal ecosystem services of water quantity, water quality, and biodiversity be impacted by the: (1) transition in land uses from wildland to urban and peri-urban; (2) changes in climate; and (3) interactions between changes in land use and climate including both on-site and off-site feedbacks?

Our research is organized into five components. These are designed to provide critical within-system knowledge across a range of temporal and spatial scales by examining processes associated with (1) Parcel-Level to Regional Decision Making, (2) Longitudinal Variation in Hillslope, Riparian, and Stream Ecology, (3) Impacts of Climate and Land Use Change on Biodiversity and (4) Baseline Data and Temporal Reconstruction. Data and analytical results from each component will be linked through (5) Synthesis & Scaled Integration. The research provides the foundation for comparative analyses, which are increasingly necessary for understanding the local manifestations of global change whether in climate or human settlement, in ways that advance knowledge of complexity about socio-ecological systems.

During the early 20th century, forested mountain lands in the southeast were extensively grazed, cleared and planted with corn, and logged. Erosion on worn out and abandoned lands was a region-wide concern, and the rank and file of professional foresters knew little about forest effects on climate and soil. With the goal of using research to improve understanding of the influences of forests on water yield, the Appalachian Station (now called the Southern Research Station) hired Charles R. Hursh in 1926 to direct the Station's Division of Forest Influences. Some of his earliest work dealt with erosion control and methods for stabilizing soil on road-banks and abandoned agricultural land. These early studies led to an examination of water movement through the soil profile and the recognized need for continuous measurements of stream flow and precipitation.

Charles Hursh sought a suitable area for complete watershed instrumentation for continuous measurements of stream flow and precipitation so as to conduct comprehensive watershed management studies. He selected the Coweeta drainage basin on the Nantahala National Forest near Franklin, NC, for this purpose. Three thousand nine hundred acres (later increased to 5,750 acres) were set aside in 1933 as the Coweeta Experimental Forest. The Civilian Conservation Corps and the Public Works Administration provided the manpower and funds for a major weir construction program that began in 1934. Combined with a network of 56 standard rain gages, numerous ground-water wells, and meteorological stations the stage was set for a comprehensive watershed management research program. After a period of standardizing the gaged watersheds, the first treatments and experiments were initiated in 1939. Since then, scientists have conducted a variety of watershed experiments at Coweeta. The early emphasis on how land management practices affect the hydrologic cycle has evolved into a broader interdisciplinary effort that couples hydrology to its ecosystem context.

The first 50 years of research at Coweeta were synthesized at a 1984 Symposium at the University of Georgia later published as a book, "Forest Hydrology and Ecology at Coweeta." The Coweeta LTER Research Program was established in 1980. Since then, the project has evolved from a site-based project centered on the Coweeta Hydrologic Laboratory to a site and region-based project that integrates ecological and socioeconomic components across 60,000 km2 of the southern Appalachian Mountains. The project nevertheless continues to build on the need recognized by Charles Hursh for using research to help unravel the impact humans have on varied environmental conditions in order to provide solid science to guide future land use planning.