Spatial Patterns of Forest Floor pH, Nitrate, and Ammonium Associated with Bigleaf Maple and Douglas-Fir in Conifer Forest.

Plants can contribute to the spatial variation of forest floor properties, as different plant species have different nutrient demands and produce litter of differing quality. This study aimed to detect the spatial characteristics of forest floor pH, nitrate, and ammonium related to bigleaf maple (Acer macrophyllum Pursh) and Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) within conifer forest.  Two 20 x 20 m plots, centered on an individual dominant bigleaf maple and Douglas-fir respectively were sampled at 100 systematic locations and tested for forest floor pH, and concentrations of nitrate and ammonium.  To visualize overall spatial patterns, an interpolation was performed using kriging. Significant spatial patterns were characterized using isotropic Moran's I correlogram.  Results showed that pH and ammonium near bigleaf maple had a strong spatial structure with a range of about 10 m while these properties near Douglas-fir had a weak spatial structure and were more likely to occur at random. The findings of this analysis suggest a high spatial influence of bigleaf maple as compared to Douglas-fir within a coniferous forest ecosystem.