Soil legacies of past land use on the Domain

     Prior studies suggest that land use has persistent, multi-decadal effects on the spatial heterogeneity of soil resources and differences in nutrient distribution and supply could alter the composition and diversity of... [ view full abstract ]

     Prior studies suggest that land use has persistent, multi-decadal effects on the spatial heterogeneity of soil resources and differences in nutrient distribution and supply could alter the composition and diversity of forest ecosystems (Fraterrigo et al. 2005). In both temperate and tropical zones, we now know that belowground resource availability plays an important role in the formation of tree communities at local scales (John et al. 2007). At Sewanee, humans have lived on the landscape for over 9000 years, and there are several parts of the Domain that were occupied first by Native Americans and then by groups of settlers. To better understand the legacies of past land use on soil properties and forest composition on the Domain, we intensively sampled three abandoned home sites (>70 years) and adjacent forest controls on upland sites. At each home site, we sampled soils and artifacts in 41 soil test pits in a 40m radius circle that was centered on the home footprint. Inside this 40m sampling radius, we also measured and mapped all trees > 2cm diameter. Charcoal was found in surface soils at all three sites, and historic artifacts were common at all three sites as well. Pre-historic artifacts were found in 2 of the 3 sites. In the home sites, A horizon depth, pH, and concentrations of base cations, Na, Zn, As and P were statistically higher (p ≤ 0.05) in surface soils compared to adjacent forest. Thirty-three tree species were encountered at the home sites, and we used geospatial statistics (kriging) to estimate soil chemical properties under each tree that was encountered. This data was then analyzed through principal component analysis (PCA) to better understand how soil chemical properties contributed to the spatial distribution of the different tree species. Concentrations of K, N, As, Na, S, Ca and pH contributed most of the variation related to the spatial distribution of the different tree species growing on the abandoned sites.