PS 25-96
Parent material, N cycling, and foliar chemistry in northern hardwood forests
The weathering of parent material is the primary source of Ca, Mg, K, and P in soils and ecosystems. The influence of parent material on N cycling is less often investigated. The objective of this study was to examine foliar nutrients and soil mineralization in relation to parent material in 20 sites in the White Mountains of New Hampshire, USA. We measured concentrations of total Ca, Mg, K, and P in C horizon material collected in 1-3 soil pits per site. Nitrogen mineralization was measured in laboratory incubations of Oe horizon material. Leaf litter was collected and analyzed for N, P, Ca, Mg, and K by species: sugar maple (Acer saccharum Marsh.), American beech (Fagus grandifolia Ehrh.), yellow birch (Betula alleghaniensis Britt.), white birch (Betula papyrifera Marsh.), red maple (Acer rubrum L.), and pin cherry (Prunus pensylvanica). Hierarchical cluster analysis was applied to nutrients in the C horizon. A two-way ANOVA was used to investigate the effect of parent material type and tree species on foliar nutrient concentrations.
Results/Conclusions
Sites fell into two clusters corresponding to the underlying bedrock and presumably the glacial till parent material. One cluster was 5 sites located on Rangely schist; the other 15 sites were on Conway and Mt. Osceola granites. This distinction in parent material was reflected in foliar Mg and P concentrations, with higher foliar concentrations in sites on the schist than on the granites (p<0.0001). There was no difference in foliar Ca concentration on the two lithologies (p=0.30). Surprisingly, foliar N concentrations were higher in sites on the schist than the granites (p<0.0001). However, N mineralization rates were not significantly different between these two groups of sites (p=0.68). Parent material may deserve more attention as a control on N accumulation in ecosystem development.