Vezzoli R, De Michele C, Pavlopoulos H, Scholes R J
DIIAR, Politecnico di Milano, Milan, Italy.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 May;77(5 Pt 1):051908. doi: 10.1103/PhysRevE.77.051908. Epub 2008 May 13.
In drylands the soil water availability is a key factor ruling the architecture of the ecosystem. The soil water reflects the exchanges of water among soil, vegetation, and atmosphere. Here, a dryland ecosystem is investigated through the analysis of the local interactions between soil water and vegetation forced by rainfall having seasonal and stochastic occurrence. The evolution of dryland ecosystems is represented by a system of two differential equations, having two steady states, one vegetated and the other unvegetated. The rainfall forcing is described by a diffusion process with monthly parameters. In each of the two possible steady states, the probability density functions of soil water and vegetation are derived analytically in terms of the rainfall distribution. The results show how the seasonality of rainfall influences the oscillation of the ecosystem between its vegetated steady state during the wet season and its unvegetated steady state during the dry season.
在干旱地区，土壤水分有效性是决定生态系统结构的关键因素。土壤水分反映了土壤、植被和大气之间的水分交换。在此，通过分析降雨引发的土壤水分与植被之间的局部相互作用来研究干旱地区生态系统，降雨具有季节性和随机性。干旱地区生态系统的演化由一个包含两个微分方程的系统表示，该系统有两个稳态，一个是植被覆盖状态，另一个是无植被状态。降雨强迫由具有月度参数的扩散过程描述。在两种可能的稳态中的每一种状态下，根据降雨分布解析得出土壤水分和植被的概率密度函数。结果表明降雨的季节性如何影响生态系统在雨季的植被覆盖稳态和旱季的无植被稳态之间的振荡。
