PARENT SESSION
Oral Session #104: Plant Communities: Vegetation Analysis.
Presiding: S. Will-Wolf
Friday, August 9. 9:00 AM to 12:00 PM. Grand Ballroom West, Radisson.
The GLADES project: Tree demography and landscape analysis in a 16 Ha oak savanna grid.
DAVIS, MARK*,1, 1 Macalester College, Saint Paul, MN
ABSTRACT- In the late 1980s and early 1990s, a 16 ha grid (10 x 10 m cells) was established in an oak savanna/woodland at the Cedar Creek LTER site, thereby initiating a long term monitoring study, now referred to as GLADES (Grid for Landscape Analysis and Demographic Study) Project. The grid has been divided into three burn units, and the three units have experienced different fire regimes since 1987. In 1995 and 1996, all trees greater than 2 cm dbh (totaling more than 11,000 trees) were tagged and measured (dbh). The status of these trees (live or dead) has been recorded annually since then and dbh was remeasured five years after the initial measurement. A high resolution topographic data set was constructed for the site, and LAI, percent bare soil, and total soil carbon and nitrogen were measured in all 1600 cells. Aerial photographs of the site have been taken in 1988, 1993, and 1999, and reference photographs were taken of each cell in 2001. All data and photographs are managed using a GIS and are accessible on the Cedar Creek LTER website. Analysis to date shows distinctly different mortality and growth patterns among trees on the grid, with size, species, and burn unit being the three variables most strongly correlated with these patterns. Growth and/or mortality of some species was also found to be associated with landscape location involving differences in elevation, soil N, bare ground, and local tree density. We expect future data collection and analysis to help us evaluate the applicability of deterministic, stochastic, and neutral models in understanding the spatial and temporal distribution of tree species at this site.
KEY WORDS: oak savanna, landscape analysis, tree demography, long term monitoring