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Title: Soil Moisture Spatial Patterns in a Uniform Paulownia Tree Stand

item Cosh, Michael

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2007
Publication Date: 11/2/2007
Citation: Cosh, M.H. 2007. Soil moisture spatial patterns in a uniform Paulownia tree stand. In: Proceedings of the Second International Symposium on Soil Water Measurement using Capacitance, Impedance and Time Domain Transmission, October 28-November 2, 2007, Beltsville, Maryland. Paper No. 1.5, p. 1.5-1-10.

Interpretive Summary:

Technical Abstract: Soil moisture spatial patterns have been studied at length in agricultural fields and pasture/rangelands as part of the USDA soil moisture satellite validation program, but recent research has begun to address the distribution of soil beneath a forest canopy. Forests cover a significant portion of the land surface and as yet unexplored element of soil moisture satellite remote sensing. Starting in the summer of 2006, an active/passive microwave radiometer experiment (APEX) was conducted in Upper Marlboro, MD over three stands of Paulownia trees, each at a different spacing. Impedance (Dynamax Theta Probes) and gravimetric sampling of soil moisture for the top 6 cm were conducted at various spatial densities to determine the most efficient method of monitoring of sub-canopy moisture and temperature. Calibration equations were also developed for the Theta Probe in this specific soil type. Stevens Water Hydra probes also monitored soil moisture and temperature hourly for extrapolation of moisture throughout the day and between intensive experimental operations. The sub-canopy was very homogeneous with minor effects due to sun penetration at the edges of the tree stands. The coastal plain soils had high moisture content throughout the summer ranging from a high value of 45% volumetric soil moisture (vsm) to a low value of 27%. On average, the soil moisture content was approximately 40% with standard deviations of approximately 3.5% (vsm). Future investigations between forest canopies will be more efficient and accurate with the improved sampling techniques and calibration equations developed during this experiment.