People are being drawn to South Carolinaís coast in ever increasing numbers. Between the years 1960 and 2010, the population of coastal counties in the United States is projected to grow from 80 to 127 million people. Population growth creates a number of environmental problems, including nonpoint source pollution, nutrient enrichment, resource depletion, and habitat loss or fragmentation. Coastal zone managers are aware of the potential for increasing human-induced stress in our coastal ecosystems. They need information, in an accessible form, to determine how present and future land use can affect the conservation and protection of various habitats and their associated biological resources.
The Ashepoo-Combahee-Edisto (ACE) Basin of South Carolina has a largely undeveloped landscape consisting of extensive, diverse habitats, such as saltwater and brackish-water marshes, maritime forests, upland pines, and bottomland hardwoods. These ecologically important attributes, coupled with management goals that balance conservation of natural resources with economic development and population growth, have made the ACE Basin the focus of national attention. A number of organizations and local citizens have been instrumental in the conservation of the ACE Basin; these include the South Carolina Department of Natural Resources (SCDNR), The Nature Conservancy (TNC), Ducks Unlimited (DU), Colleton County, and the U.S. Fish and Wildlife Service (USFWS). Through these and other organizations, nearly 10 percent of the upland and wetland habitats in the Basin have been permanently protected by purchase and conservation easements. Local community leaders have been responsive to this effort and created the ACE Basin Economic Forum with these goals: establish a framework for responsible growth, enhance awareness and appreciation of the Basin, and promote environmentally compatible business development in the area. This is particularly important considering that a population increase in the ACE Basin will undoubtedly lead to human-induced stress on its ecosystem.
Residential and urban land use in the ACE Basin study area increased by over 4,940 ha (2,000 ac) between 1989 and 1994. Colleton County, in which the majority of the ACE Basin study area is located, is expected to increase from a 1990 population of 34,377 people to over 47,500 people by the year 2010. Stressors associated with population growth include habitat loss, resource depletion, nonpoint source pollution, and nutrient loadings to estuaries and coastal waters. Areas of rapid population growth are centered within an hourís drive north (Charleston) and south (Beaufort) of the ACE Basin study area, creating the potential for rapid urbanization within the area. People are attracted to the mild climate, rural character, affordable land prices, recreational opportunities, and natural settings available in the vicinity of the ACE Basin, yet population growth and urbanization may affect the very things that attract people to the area.
The ACE Basin Characterization Study is a joint effort between the SCDNR and the National Oceanic and Atmospheric Administrationís Coastal Services Center (NOAA CSC), with contributions from numerous other agencies. The study was developed to provide agencies, land managers, resource managers, conservation groups, scientists, and private citizens with an interdisciplinary synthesis of information about this ecologically important area of South Carolina. In particular, this study was designed to present technical information in a format that is understandable to resource managers and educators. The primary goal is to facilitate management and resource allocation in the ACE Basin and surrounding areas by assembling into one information resource much of the environmental, socioeconomic, and resource management information necessary to make cogent decisions. A major emphasis of the ACE Basin Ecological Characterization is to explore the linkages between land use within a watershed and the ecological and sociological changes that result.
The ACE Basin Characterization study area consists of approximately 320,000 ha (790,000 ac) and extends approximately 72 km (45 mi.) in a northwest to southeast orientation with an approximate width of 40 km (25 mi). The study area encompasses the Ashepoo, Combahee, and Edisto River basins from the Atlantic Ocean upstream to approximately 8-11 km (5-7 mi) northwest of Walterboro with portions located in Colleton, Charleston, Beaufort, and Hampton Counties. The boundaries of the study area are primarily based on Natural Resource Conservation Service hydrologic units or watersheds. This use of watershed units to define boundaries is consistent with an ecosystem approach to resource management and reduces emphasis on political boundaries such as those used to define cities or counties. Management activities that are planned and implemented from an ecosystem and watershed perspective are much more effective in protecting and restoring habitats and resources than strategies that are isolated from the watershed approach (Shabman, 1996).
Over the last 20 to 30 years, scientists and resource managers have begun to combine a wide variety of once independent disciplines into concepts of landscape ecology, ecosystem evaluation, and integrated resource management (Kineman and Parks 1996). Using this approach, habitats are now managed as a complex, integrated system based on assorted characteristics such as sediment type, water quality, water flow, contaminants, weather patterns, and social and economic factors. The renewed interest in managing natural resources using a comprehensive ecosystem-based framework recognizes humans as a dependent and integral component of the functioning ecosystem, rather than separate and independent of it (Meffe and Carroll 1994; Kineman and Parks 1996).
Existing information and data on the ACE Basin and its resources is largely fragmented, specific to certain technical disciplines, and not readily available. This characterization integrates and summarizes available information for the ACE Basin, providing both data and descriptive text in an accessible and understandable format. The characterization is published as a "Web page" on Compact Disk (CD-ROM) and the World Wide Web utilizing a digital, hypertext environment. Such a format allows navigation within and among components and facilitates updating of the product as new issues arise or new information becomes available. Combining information from a number of disciplines in an interactive format with analytical capabilities enhances the user's ability to access and manipulate data for temporal, spatial and thematic comparisons. Users of this product are encouraged to review the "About this CD-ROM"; and "Introduction" chapters in the General Information section to learn more about the purpose and structure of this product (including navigation tools).
Information is presented in three main components: (1) spatial data, (2) narrative text on specific aspects of the Basin, and (3) synthesis modules (these are described briefly in the introduction and more extensively elsewhere in the Executive Summary).
Spatial (geographic) data relevant to the ACE Basin Characterization are included in the digital characterization. Approximately 100 data layers include topography, wetlands, land use, wildlife populations, hypsography, hydrography, and census information and may be viewed independently or superimposed to compare relative spatial properties. Tabular data, such as water quality or sediment contaminants, are associated with some spatial data layers. The ability to display and manipulate spatial and tabular data provides a powerful tool for managers who must evaluate potential changes affecting resources in an area. The data can be displayed and manipulated using geographic information systems (GIS) software. ArcViewâ project files and shape files are included for those users with Environmental Systems Research Institute's (ESRI) ArcView software. ESRIís viewing tool, ArcExplorerâ is also available on the CD-ROM for those users without ArcView.
The narrative text provides the reader with a synthesis of the physical setting, biological setting, socioeconomic resources, and important ecosystem interactions in the ACE Basin and nearby coastal areas. Historical activities including land clearing for agriculture, impounding wetlands for rice cultivation, and harvesting timber resources are discussed to provide a record of past resource use. Descriptions of the environmental conditions in the ACE Basin include its geology, geomorphology, hydrology, climate, water quality, soil characteristics, biogeochemistry, and hydrochemistry and pollution. Information on the ecological community includes descriptions of representative ecosystems, faunal assemblages, and ecosystem processes within the study area. Current resource uses including agriculture, forestry, commercial and recreational fisheries, hunting, and upland development activities are described. A section on the socioeconomics of the ACE Basin provides information on its present and potential future social and economic makeup. Management of natural resources including both the wildlife and habitat is discussed in the resource management section. Tables, figures, and pictures are included in each text section to help summarize and display information.
The synthesis modules, the third major component of the ACE Basin Characterization, provide integrated summaries of two major concerns in the Basin: water quality and land use. The water quality and land use modules summarize relevant ecological and socioeconomic information (with links to narrative text sections) and discuss issues and management options.
In addition to the main components, supporting information and navigation tools are provided to enhance the ability of the audience to access, comprehend, and utilize the information contained in the product.
It is the goal of this characterization that it be a tool that agencies, local governments, land managers, conservation groups, and private citizens use to understand and conserve the unique character of the ACE Basin. By providing an overview of the ecosystem dynamics and issues of the ACE Basin, this characterization is also a valuable research, teaching, and educational tool. Finally, by providing insight into the past, present, and future of the ACE Basin, it is hoped that this characterization will contribute to science-based decision making within the Basinís watershed. (See related section: Introduction .)
The ACE Basin Characterization includes a geographic information system (GIS ) component. GIS is a computerized system for the collection, organization, analysis, and display of data with a spatial (geographic) reference. A GIS organizes spatial information for display as maps, tables, or graphs and empowers people to analyze the information for spatial relationships among multiple layers of data. The information in this product is provided to allow environmental professionals, land use planners, and the public to visualize and assess spatial relationships among important attributes of the ACE Basin.
A decision was made at the start of the ACE Basin Characterization project to base evaluations of the status and management options for the ACE Basin ecosystem on a comprehensive watershed approach. Much of the data collected in the ACE Basin extends beyond the boundaries agreed upon using the watershed approach. Because of this, all of the spatial data layers were clipped to the watershed boundaries, thus eliminating any data not contained within the project boundary. Data layers included on this product were chosen based on their integral relationships to the ACE Basin ecosystem. Spatial data sets available in this characterization are provided as ArcView shapefiles and accompanying data tables. The shapefiles include point, line, and polygon vector coverages representing a variety of spatial data themes. Examples include sediment sampling locations (point), elevation contours (line), and National Wetlands Inventories from 1989 and 1994 (polygon). These data layers can be viewed with the ArcExplorerÒ software provided on the CD-ROM or with ArcViewÒ software if it is available to the user.
There are many advantages to putting data into a GIS: It allows the user to investigate the spatial array of data; data can be manipulated by overlaying data layers and performing queries; the panning and zooming functions of GIS software allow the user to focus on particular areas of interest; additional, specialized customizations of the software allow the user increased analytical techniques and abilities. GIS software also provides the user with the ability to create maps displaying any combination of the data layers desired. These maps can be saved in digital form or can be printed out as hard copy. In addition, the user can modify the provided ACE Basin ArcViewÒ Project by adding or removing data layers, creating new views or layouts, and organizing view coverages or similar subject matter in a single view.
GIS will facilitate learning by allowing students of all levels to manipulate data in queries. Land use managers can use it to make management decisions. Scientists can use it to look for areas where historical studies have been done and where new studies are most needed. The GIS database can be added to existing databases or can be supplemented in the future to make a more comprehensive database. The dynamic qualities of a GIS open up numerous possibilities to its users.
For more information about using the spatial data provided on this CD-ROM, see the GIS Data section.
Next Section: Executive Summary: History
E. Wenner, SCDNR Marine Resources Research Institute