Dynamics of Coupled Soil Moisture and Plant Capacitance Systems from Daily to Interannual Scales

Abstract

Plant water storage capacity can be a major component in the water balance between soil and plant life, but there are challenges to analytically predicting the distribution of soil moisture and plant water values under stochastic rainfall. Existing analytical models of soil moisture under stochastic rainfall in plants with negligible capacitance have improved understanding of plant stress, productivity, and hydrology. In this study, we use a resistance-capacitance model of plant hydraulics coupled with photosynthetic mechanisms to study the relationship between soil moisture and plant water storage capacity under stochastic rainfall. By varying rainfall and storage volume, we identify changing characteristics of the plant-soil water system under different conditions. This study finds that non-uniqueness in the relationship between plant water and soil water can be closed in some cases at longer time scales. Plant water storage dynamics may also play a role in actively modulating soil moisture at large storage volumes.