Spatial structure of hydraulic properties from canopy to interspace in the Mojave Desert

Desert piedmonts are a mosaic of interspersed vegetation and bare soil, previously considered to be a binary system of canopy and interspace microsites. The spatial structure of soils and hydraulic properties in these microsites affects our ability to upscale or downscale observed processes. We determined variability and spatial correlation of hydraulic properties using high-resolution measurements of unsaturated hydraulic conductivity [ K(psi)] along linear transects radiating from canopies of perennial shrubs common to the Mojave Desert into bare soil interspaces. Hydraulic conductivity from -6 < Psi < 0 cm soil water pressures was lower under canopy. Spatial correlations to organic matter, particle-size, and K(Psi) were observed to approximately 1.4 times canopy diameter, beyond which random processes dominated. Results illustrate that a predictable spatial structure in K(Psi) exists between canopy and interspace microsites and suggest that scaling from the plant to field plot could exploit this relationship. Citation: Caldwell, T. G., M. H. Young, J. Zhu, and E. V. McDonald (2008), Spatial structure of hydraulic properties from canopy to interspace in the Mojave Desert, Geophys. Res. Lett., 35, L19406, doi: 10.1029/2008GL035095.