System for computing multiple soil moisture regimes

点击翻译按钮获取中文摘要

The availability of water is often the single most important determinant of not only the distribution and abundance of individual plant species but also of terrestrial plant diversity in a locality or region.  Unfortunately, the water available to individual plants is not easily quantified.  Adjacent soils can differ in the way they retain and release water from a precipitation event, and precipitation itself has high spatiotemporal variability. Plants also vary in their capacity to extract water from soil at differing water contents. One can fairly easily make continuous or intermittent measurements of soil water content, but it is soil water potential (a measure of the energy required to extract water from the soil), not simply water content, that determines the water a plant can acquire. The relationship between soil water potential and the volumetric water content of soil is referred to as the soil-water release curve or soil moisture characteristic (SMC). Different types of soil have distinctive SMCs, so simply measuring soil moisture content will not yield a useful estimate of the range of water availability in which a given plant species can survive and grow.  The measured soil moisture contents need to be converted to soil water potentials, which are not readily measured directly under field conditions. the requested Decagon WP4-T dewpoint potentiameter can be used in the laboratory to determine the SMC for individual soil samples collected in the field. By determining the SMC for soil in the root zone of individual plants we can better characterize and compare measured soil moisture regimes among different plant species, and additionally the mathematical parameters describing the shape of the SMC in soils where a plant species is found can be considered a meaningful characteristic of the environmental niche occupied by a species.  Analysis of these data can tell us quite a lot about controls on the distribution and abundance of species. This knowledge in turn can help predict the impacts of climate change on patterns of plant distribution and diversity in regions where precipitation regimes are predicted to shift in coming decades.