System for computing multiple soil moisture regimes

水的可利用性往往是一个地方或区域中不仅是单个植物物种的分布和丰度而且也是陆生植物多样性的唯一最重要的决定因素。 不幸的是，单个植物可用的水不容易量化。 相邻土壤在降水事件中保持和释放水分的方式可能不同，降水本身具有很高的时空变异性。植物从不同含水量的土壤中提取水分的能力也各不相同。人们可以相当容易地连续或间歇地测量土壤含水量，但土壤水势（从土壤中提取水分所需能量的量度），而不仅仅是含水量，决定了植物可以获得的水分。土壤水势与土壤体积含水量之间的关系称为土壤水分释放曲线或土壤水分特征（SMC）。不同类型的土壤具有不同的SMC，因此简单地测量土壤水分含量不会产生对给定植物物种可以生存和生长的水可用性范围的有用估计。 测得的土壤含水量需要转换为土壤水势，这是不容易直接在现场条件下测量。所要求的Decagon WP 4-T露点电位仪可在实验室中用于确定野外采集的单个土壤样品的SMC。通过确定单个植物根区土壤的SMC，我们可以更好地表征和比较不同植物物种之间测量的土壤水分状况，此外，描述植物物种所在土壤中SMC形状的数学参数可以被认为是物种所占据的环境生态位的有意义的特征。 对这些数据的分析可以告诉我们很多关于物种分布和丰度的控制。这方面的知识反过来又有助于预测气候变化对未来几十年降水状况预计将发生变化的地区的植物分布和多样性模式的影响。

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.