Wetlands

Wetlands research at the Jones Center.The Dougherty Plain of Southwest Georgia is a unique coastal plain region that is distinguished by a complex limestone geology interlaced with extensive subsurface aquifers and surface wetlands. Scientific knowledge and stewardship of these water resources are both essential to the future environmental and economic health of South Georgia.

A distinctive feature of the Dougherty Plain is the abundance of wetlands which range from small isolated ponds to large expansive swamps or narrow fringes along streams and rivers. In general, wetlands are known to provide a broad array of goods and services to society, such as habitat for wildlife, flood protection, clean water and recreation. However, the values and functions that are characteristic of these wetlands in the Dougherty Plain are poorly understood.

Limesink wetlands

Limesink wetlands are common in southwestern Georgia. They are shallow ponds isolated from stream and river drainages. Their vegetation varies from grassy meadows to forested swamps. The size and shape of limesink wetlands is also variable, ranging from small “sinkholes” with steep sides to large shallow basins of many acres. Geologists think that limesink wetlands form when limestone bedrock deep within the ground is dissolved by ground water and surface soils collapse.

Scientists speculate that newly formed sinkholes drain directly into underlying aquifers, rapidly transferring rainfall to the water table. The bottoms of older sinkholes appear to become sealed by silt and sediments, forming ponds during extended rains. The unique vegetation and animals associated with older sinkhole ponds results from their water holding ability.

Water managers are interested in the role limesink wetlands may play in resupplying groundwater and in potential contamination of groundwater from agricultural pesticides, waste disposal associated with chicken or dairy farming operations, or urban runoff.

Riparian wetlands

Riparian wetlands are wetlands associated with rivers and streams. They are formed as streams repeatedly overflow their banks, alternately eroding soils and depositing sediments. Similar to limesink wetlands, riparian wetlands support a diverse group of plant and animal species that can live in seasonally flooded conditions. Water managers are interested in the role of riparian wetlands in reducing the severity of floods and in maintaining water quality.

During floods, streams and rivers expand and overflow their banks. Floodplain vegetation slows the flow of water, reducing the size and rate of flooding downstream. Riparian wetlands also act as filters, absorbing nutrients and sediments that run off developed areas adjacent to stream corridors.

Ecological functions and values of wetlands

Answers to fundamental questions about the functional role of wetlands in the Dougherty Plain are particularly critical in southwest Georgia because of extensive agricultural land-use, growing regional developmental pressures, and the need to protect valuable surface and ground water quality.

Many limesink and riparian wetlands have been developed or converted to agriculture or are impacted by adjacent land uses. Others have been drained or altered by “flood control” projects.

Development of appropriate wetland protection systems, regional land-use planning, and land management decisions require an understanding of the wetlands functions in the Dougherty Plain and of encroaching threats to these systems.

At Ichauway, wetland research is focused on the following basic questions:

Research at Ichauway is unique in that the large number of undisturbed wetlands provides an opportunity to determine basic wetland function. It also permits comparison with surrounding areas more heavily influenced by humans.

Direct applications of wetlands research at Ichauway will result in protection of clean water and wildlife habitat, better regional land planning, the development of better decision making tools for natural resource policies, and in providing models for wetlands research.

By examining the effects of agriculture, forestry, and urbanization on the ability of wetlands to support plants and animals, and the degree to which current legal boundaries protect ecological functions, more effective, land management policies can be implemented within the region.

Ecology of Wetlands

The ecological functions of wetlands fall into three broad categories:

  1. hydrologic—sources of water, flowpaths, water cycles;
  2. biogeochemical—role in transformation and movement of nutrients, sediments, and pollutants;
  3. biological—contribution to food webs and role as habitat.

Many wetland functions are dependent on the movement of water between uplands, wetlands, groundwater and permanent stream drainages. Thus, the value of wetlands to society is best viewed in a regional context.