Eco-Geophysical Imaging of Watershed-Scale Soil Patterns Links with Plant Community Spatial Patterns

The extent to which soil moisture and nutrient availability control the structure, function, and diversity of plant communities has aroused considerable interest in the past decade and remains topical in light of global change. Numerous plant communities are controlled either by water or soil nutrient availability, and yet spatial patterns of soil properties affecting resource pools, such as texture, are often poorly delineated at the landscape level. Traditional soil survey methods, developed for land evaluation, remain largely qualitative, based on the subjective analysis of the soil surveyor and often using vegetation patterns to demarcate soil boundaries. To date, no independent method of determining the properties of soil root-zone spatial patterns has been developed for use at the landscape scale, resulting in a knowledge gap between observed aboveground vegetation patterns and the distribution of belowground soil properties. The objective of this work was to determine whether a quantitative link could be observed between bulk soil electrical conductivity, used as an indicator of soil texture, and the plant community spatial pattern using geophysics. By comparing the geophysical signal with plant community patterns, we have discovered distinct vegetation niches corresponding to distinct zones of bulk soil electrical conductivity. A hierarchical ranking of the mean bulk soil electrical conductivity for each plant community type follows a power-law structure.