Potential for the use of GIS and spatial analysis techniques to integrate information and understanding of   microsite topography, soil attributes, surface hydrology, and tree growth

Yi-Jun Xu
Department of Forestry
Virginia  Polytechnic Institute and State University
Blacksburg, VA
James A. Burger
Department of Forestry
Virginia  Polytechnic Institute and State University
Blacksburg, VA
W. Michael Aust
Department of Forestry
Virginia  Polytechnic Institute and State University
Blacksburg, VA
Steven C. Patterson
Forest Science Laboratory
Westvaco Corporation
Summerville, SC

ABSTRACT

Microsite variables such as elevation, soil attributes, and surface water table in forested wetlands are heterogenous. The spatial heterogeneity is an inherent feature of site conditions with significant functional implications. This study proposes a scheme for combining microsite variables and tree growth data to address the following three questions: 1) can geostatistical analyses provide critical information on spatial associations among site conditions and tree growth at the stand level? 2) can GIS be used to generate maps of site variables and tree growth to present spatial and temporal trends? and 3) are GIS applications useful for stand-level dynamic modeling of soil water and tree growth? As a long-term study on maintaining productivity and functions of intensively-managed wetland forests in the southeastern US, three 20-ha wetland pine plantations on the coastal plain in South Carolina were chosen for establishing a sustainability monitoring system. Elevation, water table depth, soil attributes, and tree growth at age 23 were measured on each point of a 20m by 20m grid system laid out across the study sites (a total number of grid points: n=1409). Water table depth was measured monthly for 6 years. Results show that spatial patterns of site conditions are highly variable. Temporal fluctuations in the surface water tables of all sites were also highly variable. Analyses of the data show that GIS and geostatistical applications are powerful tools, not only for storing digital objects, but also for spatial and temporal analyses of the interrelationships among these objects.