Field-based Near-Infrared Reflectance Spectroscopy for Spatially Explicit Quatification of Forest Soil-site productivity relationships.

Studying the distribution of soil properties in the field is germane to understanding soil as a natural body in the landscape.  Soils usually exhibit non-random, spatial variation and increasingly geostatistics are being used to elucidate the soil processes behind these patterns. Using a field-portable near-infrared reflectance spectrophotometer we measured forest soil carbon, nitrogen, and clay content to 1 m depth in a 40 x 40 m grid across 4 ha of managed pine forest.  We correlated the spatial distributions in these soil attributes among themselves as well as with slope, tree height, and tree groundline diameter distributions.  Soil C, N, and clay content were well correlated across the landscape.  Slope attributes also demonstrated a significant relationship with clay content and  soil C.  Tree growth parameters were not strongly correlated with C, N, or clay content.