Coastal Forests and Groundwater: Using Case Studies to Understand the Effects of Drivers and Stressors for Resource Management

Abstract

Abstract:Forests are receiving more attention for the ecosystem goods and services they provide and the potential change agents that may affect forest health and productivity. Highlighting case examples from coastal forests in South Carolina, USA, we describe groundwater processes with respect to stressors and potential responses of a wetland-rich forested landscape, the roles that this area has served, and the need for water resource data to inform forest management decisions. Forested lands in the southeastern U.S. coastal plain provide a rich set of goods and services for the region, and in one case, the Francis Marion National Forest acts as a buffer to urbanization from the surrounding Charleston metropolitan area. Information from two decades of studies in the forested watersheds there may inform scientists and managers in other coastal forested systems. The common hydrological theme in this region, which has a higher average annual rainfall (1370 mm) than the annual potential evapotranspiration (PET = 1135 mm), is a shallow (<3 m) water table condition that supports a large range of natural wetlands and also creates management challenges across the region. Modest changes in the position of the water table can lead to either groundwater flooding and concomitant management challenges for forest services, or ecosystem stresses related to dry conditions in wetlands during times of below-normal precipitation or due to groundwater withdrawal. Development pressures have also stressed forest resources through the extraction of materials such as timber and sand mining, and the conversion to housing construction materials. These areas are also targeted for land development, to meet housing demands. In this paper, we discuss the role of groundwater in coastal forests and highlight opportunities for collaborative studies to better inform forest resource management.

Forest fire effects on groundwater in a coastal aquifer (Ravenna, Italy)

“…Vegetation, in fact, plays an important role in the water cycle. Forests have contrasting feedbacks on groundwater resources (Callahan, Amatya, & Stone, ) depending on the climate system and the morphology of the territory. A positive feedback is the shading of the canopy that prevents soil evaporation.…”

Stormwater Ponds in the Southeastern U.S. Coastal Plain: Hydrogeology, Contaminant Fate, and the Need for a Social-Ecological Framework

“…Average annual rainfall in the southeastern U.S. is about 110 cm in the upper (inner) coastal plain to about 130 cm in the lower coastal plain of South Carolina (Amatya et al, 2018) to 150 cm in northern Florida (NOAA, 2019). This water input has been, on average, approximately balanced by evapotranspiration (ET) of coastal plain forests (Harder et al, 2007;Callahan et al, 2017;Amatya et al, 2018). Freshwater runoff from any undeveloped uplands of the coastal plain is relatively small in volume because of the relative ease of water infiltration into the sandy upland soils, however, with land development in and around metropolitan areas, increased impervious surface coverage has led to larger volumes of stormwater runoff to receiving water bodies, including streams and rivers, tidal creeks and marshes, and the coastal ocean (Sanger et al, 2015).…”

Hydrometeorological Trends in a Low-Gradient Forested Watershed on the Southeastern Atlantic Coastal Plain in the USA

“…The main factor influencing recharge estimates was antecedent water table level, which in turn was influenced by landscape position and soil texture. The shallow water table conditions at this site support a large range of natural wetlands and create management challenges across the region [103]. Modest changes in the position of the water table can lead to either groundwater flooding and concomitant management challenges for silvicultural activities, or to ecosystem stresses related to dry conditions in wetlands during times of below-normal precipitation or because of groundwater withdrawal.…”

“…The Gordon Aquifer (hydrogeologically equivalent to the Floridan Aquifer) is locally confined by a low permeability unit in the form of the Parkers Ferry Formation in the western portion of the Turkey Creek watershed; this unit is absent beneath the eastern half of the watershed. Previous research showed an average of about 50-175 mm per year of recharge from analysis of groundwater level data in the eastern section [103]. Forested watersheds such as Turkey Creek serve as an important water reservoir and provide services to groundwater-dependent ecosystems [119].…”