On Entropy, Plant Water Stress, and Water Use Strategies

Applications of thermodynamic principles to ecology have a relatively long and varied history. These applications may rest on the concepts of non-equilibrium thermodynamics developed by Prigogine and others or even on a basic analogy between thermodynamic and ecological systems. We evaluate the potential of thermodynamic entropy minimization as an organizing principle in the ecohydrology of water-limited ecosystems. In particular, an entropy budget is derived and related to plant water stress for the idealized case of a single plant. Water use strategies of individual plants are then discussed in relation to entropy generation subject to a stochastic soil moisture process, including dependence on parameters such as rooting depth and maximum evaporation. Possible implications of the entropy model for temporal and spatial patterns of vegetation occurrence are then examined.