Experiment B
Short Rotation Silvicultural Impacts on Water Resources
and Biodiversity: A Watershed-Scale Experiment

Current silvicultural practices in the southeastern US are not considered to have a deleterious effect on water resources, but they may affect biodiversity. However, assuming minimal impacts on water resources is less certain as the management intensity increases. There is a need for experiments that consider larger scale environmental implications of intensively managed SRWC systems.

Study Description: The study is located at the Savannah River Site on gently sloping ground in the sand hill region of South Carolina’s upper costal plain. Ten individual basins are defined to catch runoff and subflow leaving the site. Two irrigation treatments are used for characterizing the influences of added water to nutrient and chemical movement. Water was selected as the primary treatment due to its principal role in nutrient and chemical transport. Although fertilization levels influence nutrient lost, we have not included fertilization as a treatment, and have chosen to use one high rate as a way of “pushing” the site and testing our understanding of the mechanisms controlling nutrient retention and movement. We have also kept other silvicultural treatment factors constant.

The large plot size (5 to 10 acre) and the proximity to streams also provide an opportunity to study the impact of intensive management on invertebrate and avian diversity and buffer zone processes. Invertebrates are particularly important faunal components of forested landscapes, as well as the primary trophic link between plant production and higher vertebrates. Additionally, avian diversity varies with stand development and is affected, both positively and negatively, by various silvicultural practices. Intensity of management in short rotation stands may have a significant impact on associated avian communities.

Objectives:

• Test our understanding of the factors and processes controlling nutrient and chemical transport from forested catchments under intensive silvicultural prescriptions.
• Test if there are forest type interactions with ecosystem process affecting nutrient and chemical transport.
• Establish a carbon nutrient budget, including inputs and outputs, from intensively managed stands.
• Determine the influence of intensively cultivated plantations on invertebrate and bird diversity.

Status: Monitoring of all catchments, to calibrate in their current mature forest conditions, commenced during the 2003 growing season and will continue for at least one annual cycle. The irrigation system is planned and contracting has commenced for installation. Following calibration, eight of the ten catchments will be converted to intensively managed plantations and we will monitor water quality and faunal diversity during conversion to the new forest.