Figure 3. Non-forested land declines from over 10% to less than 5% of the Little Tennessee watershed between 1950 and 1990.

We will be developing characterizations of land use and land cover on a detailed categorical level from 1800 to the present. Our 1800 onset date marks the beginning of significant Euro-american settlement in the southern Appalachian Mountains. This onset date allows us to evaluate the effects of critical turning points in the transformation of Appalachia (Salstrom 1994, Dunaway 1996, Yarnell 1998) including the start of market segmentation in 1820, the apogee in forest clearing after 1900, and the recreation and real estate boom beginning in 1970. By combining independently derived social, economic, and biophysical evidence (e.g. U.S. Census and State records of various kinds, historical cartography, aerial photography, eyewitness and personal accounts, satellite data, etc.), we will be able to map historic and current patterns across the region that address the following questions:

1. How does land use/land cover vary across spatial, temporal and measurement scales?
2. What are the spatial and temporal linkages between biogeophysical and socioeconomic processes?
3. How is previous transformation of a site linked to subsequent transformation of the same and surrounding sites?

Once these land-use trajectories are evaluated through information-theoretic techniques (Wear and Bolstad 1998) the results will then serve as the cartographic template for other research projects.

Previous Research on Topic

Available Educational Opportunities

Investigators
Ted Gragson, U of Georgia, Human disturbance processes
Paul Bolstad, U of Minnesota, Forest Processes
David Wear, USDA-USFS, Forest Economic Modeling

Environmental Gradients

One of the defining characteristics of the southern Appalachian Mountains is significant and predictable environmental heterogeneity over small spatial scales. Understanding how gradients influence the structure and function of watershed ecosystems has been a persistent focus of the Coweeta LTER (e.g. Knoepp et al. 2000). Along the environmental gradient, the physical template appears more important in regulating ecosystem structure (i.e., community assemblages) than function (i.e., biogeochemical cycling Knoepp et al.
2000).

Long-term measurements have been made on a wide array of environmental variables at
Coweeta (Table II.2), and the measurements represent one of the most comprehensive, long term
and best-studied environmental data sets in the world. We are continuing long-term
macro- and microclimatic measurements in the Coweeta basin and to characterize the larger
region from climate, atmospheric deposition, stream chemistry and stream flow measurements
obtained from the environmental monitoring network managed and operated by state and federal
agencies (e.g., USGS, National Park Service, NCDC network). Please see our current and past research page on Environmental Gradient Research. Long term measurements are critical to future research since it provides  baseline data to analyze temporal trends (e.g., Swank and Waide 1988, Swank and Vose 1997), identify driving variables (e.g., Swank and Vose 1990/91, Vose and Swank 1993), and develop and validate spatially-explicit models (e.g., Bolstad et al. 1998).

Previous Research on Topic

Available Research and Educational Opportunities

Investigators
Barry Clinton, USDA-USFS, Response to disturbance
Katherine Elliott, USDA-USFS, Plant community ecology
Brian Kloeppel, U of Georgia, Physiological gradients
Jennifer Knoepp, USDA-USFS, Soil Processes
Wayne Swank, USDA-USFS, Hydrological dynamics/cycling
James Vose, USDA-USFS, Forest Processes
 

Disturbance Regimes
Disturbance is an important driver of southern Appalachian ecosystem structure and function that interacts with human decision-making and environmental gradients. Much of our previous research on ecosystem responses to disturbance focused on a subset of important forces acting on large scales and/or short-time intervals (e.g., the pattern and magnitude of wind damage in the Coweeta Basin from Hurricane Opal, (Hunter and Forkner 1999, Wright and Coleman 2002). We will be developing a comprehensive understanding of disturbance regimes for the region through three linked research projects focused on deriving disturbance signatures, probabilistic decadal land-use choice functions, and quantifying fluvial sedimentation patterns.

Previous Research on Topic

Available Research and Educational Opportunities

Investigators
Barry Clinton, USDA-USFS, Response to disturbance
Katherine Elliott, USDA-USFS, Plant community ecology
Ted Gragson, U of Georgia, Human disturbance processes
Jennifer Knoepp, USDA-USFS, Soil Processes
James Vose, USDA-USFS, Forest Processes

Human-disturbance: Analyses of Land-use Choices

Human land-use choices are the primary disturbance on private lands, which cover approximately 55% of our study region. Typical studies evaluate land use choice probabilities as a function of physical measures of land quality (e.g., the Von Thünen model, Samuelson 1983, the Central Business District model, Capozza and Helsley 1989), but must assume that social variables remain constant across the landscape. Historical accounts of land use in the southern Appalachian Mountains (e.g., Silver 1990, Salstrom 1994, Davis 2000) are similarly incomplete because they seldom quantify impacts across time or evaluate their heterogeneity across space. A probabilistic model  of land-use choice across the region will be derived for each decade from 1800 to the present by using land use and property records, oral histories, geneology, population and agricultural census records, and remote imagery.  The following questions will be addressed:

1. What is the relation between land use choices and changing markets, institutions and environmental conditions?

2. How do economic transitions over time relate to the nature and the distribution of land conversion?

3. How do the costs and benefits of environmental policies affect the spatial dimensions of land use decisions across time, and therefore the storage of carbon or delivery of sediment to streams?

Previous Research on Topic

Available Research and Educational Opportunities

Investigators
Ted Gragson, U of Georgia, Human disturbance processes
David Newman, U of Georgia, Forest Economics/Policy
David Wear, USDA-USFS, Forest Economic Modeling
 

 

Impacts of Historic Land-use on River Channels and Floodplains Figure 4. Little Tennessee River cutbank showing historic and prehistoric strata, and the position of a radiocarbon date of 770 BC. Long-term average sedimentation rates in the prehistoric strata are about 0.5 mm/y versus 5.0 mm/y in the historic strata. The focus of the research will be on changes in river channel morphology and bottomland sedimentation patterns in the upper Little Tennessee and French Broad River systems. These rivers and their wide alluvial valleys underwent pronounced changes beginning in the late 1700s. The changes steadily increased through the mid to late 1800s as widespread agricultural and timber-harvesting activities accelerated erosion and sedimentation across the region (Ayres and Ashe 1905, Glenn 1911). Subsequent changes in land use played an equally important role in the ongoing and complex sequence of fluvial landscape response and recovery. Preliminary observations and a radiocarbon date from an exposed stream bank (Figure 4) indicate prehistoric sedimentation rates of 0.5 mm/y, and 5.0 mm/y since 1800. Preliminary calculations suggest major morphological changes in floodplains following European settlement. We anticipate these changes can be linked to flood frequency, and ecological interaction between the channel and its floodplain. We will address the following questions in our research: 1. What is the chronology, frequency, and magnitude of floods and their interactions with vegetation and land use? 2. What is the rate of sediment accumulation and related changes in channel morphology? 3. What are the impact signatures of distinct disturbance regimes? Previous Research on Topic Available Research and Educational Opportunities Investigators Paul Bolstad, U of Minnesota, Forest Processes Fred Benfield, Virgina Tech, Stream Processes Ted Gragson, U of Georgia, Human Disturbance Processes David S. Leigh, U of Georgia, Geomorphic Process Mark Riedel, USDA-USFS, Hydrology Bruce Wallace, U of Georgia, Stream Processes David Wear, USDA-USFS, Forest Economic Modeling Jack Webster, Virginia Tech, Stream Processes