PARENT SESSION
Oral Session #74: Spatial Ecology: Models and Methods. Presiding: C. Loehle.
Friday, August 10, 2001. 8:00 AM to 11:30 AM. Hall of Ideas E.
Soil heterogeneity changes over forest succession: Quantification using univariate and geostatistical procedures.
Selin, Steven1, Mou, Paul2, Jones, Robert3, 1 2 3
ABSTRACT- We sampled forest stands in upland forests of the Southeastern US along a chrono-sequence of a replicated successional forest sere (1, 6, 10, 25, and 80 years) to elucidate the temporal changes in soil spatial heterogeneity. These trends are characterized and compared to a conceptual model of pattern dynamics. Variability in soil properties (NO3, NH4, pH, Total N, Total C) at scales relevant to individual plants was quantified using univariate and geostatistical procedures. Samples were collected from loblolly pine plantations of known ages representing reorganization through aggradation phases of succession, and from one set of oak-hickory stands to signify the steady-state phase of the model. Samples were collected both systematically and randomly in each stand. For all soil variables, the spatial variations (determined by CV) were the greatest at year 1 and lowest at year 6 or 10 (coinciding with canopy closure). Strong autocorrelation was found to occur only on some plots and at distances from 2 to 30 meters. Results from univariate analyses support the conceptual model of pattern dynamics, while geostatistical results do not support nor discredit the model.
KEY WORDS: soil, heterogeniety, succession, nutrient