While large scale, long-term forest plots are best known in tropical forests, a number of forest dynamic plots have been established in temperate forest in recent years. These allow testing the same spatial mechanisms of species coexistence in temperate forests as have been found in tropical forests – namely that intraspecific clumping and interspecific segregation can allow species to coexist. We are constructing the first forest dynamics plot (FDP) in the Southeast. The 12 hectare plot is located at the State Botanical Gardens in Athens, Georgia. This oak-hickory forest is on land that has been recovering from agricultural use for approximately 80 years. For each tree greater than 5 cm in diameter, we have recorded the location, species information, and diameter at breast height (DBH). For this study, we looked at trees with a diameter of greater than 10 cm in four hectares of the FDP. We used Ripley’s K univariate and bivariate analysis to test for clumping of single species and spatial association between pairs of species.
Results/Conclusions
1,560 individuals >10 cm representing 31 species were found in the four-hectare plot. However, 11 species represented 90% of the trees, and 17 species accounted for just 5% of the individuals. We analyzed in detail the six most abundant species. In the univariate analysis, all species were found to be clumped at small and intermediate scales, two species were randomly distributed at scales 80-100 m. Most species were found to very highly clumped. In the bivariate analysis, 15 species pairs, nine showed highly significant spatial segregation and six showed significant aggregation; no species were found to shift from segregating to aggregating across varying distances. The segregation and aggregation was consistent across all scale (distance) in bivariate comparisons. The strongest segregation was found between Fagus grandifolia and Acer rubrum and the strongest aggregation was found between Fagus grandifolia and Carya spp. Very few results were found to be random at any distance. It was very rare for pairs of species to show random distribution relative to each other at any distance. Intraspecific clumping and interspecific segregation may be important mechanisms by which temperate forest tree species coexist.