Guttal Vishwesha, Jayaprakash C
Department of Physics, The Ohio State University, 191 W Woodruff Ave, Columbus, OH 43210-1117, USA.
J Theor Biol. 2007 Oct 7;248(3):490-500. doi: 10.1016/j.jtbi.2007.05.020. Epub 2007 May 26.
Spatial self-organization including striking vegetation patterns observed in arid ecosystems has been studied in models with uniform rainfall. In this paper, we present a fully seasonal rainfall model that produces vegetation patterns found in nature by including the natural adaptation of plants to scarcity of water and the consequent seasonal variation in their growth and metabolic rate. We present results for the mean-field and spatially extended versions of the model. We find that the patterns depend on the duration of the wet season even with fixed total annual precipitation (PPT) showing how seasonality affects spatial self-organization. We observe that the productivity can vary for fixed PPT as a function of the duration thereby providing another source of observed variations. We compute the maximum vegetation cover as function of PPT and find that the behavior is consistent with observations. We comment on the implications for regime shifts due to increased interannual fluctuations caused by climatic changes. Our specific model calculations provide more general conclusions for ecosystems with competition for scarce resources due to seasonal variations in the resource, especially for self-organization and productivity.
在均匀降雨的模型中，已经对包括干旱生态系统中显著植被模式在内的空间自组织进行了研究。在本文中，我们提出了一个完整的季节性降雨模型，该模型通过纳入植物对缺水的自然适应以及随之而来的生长和代谢率的季节性变化，产生了自然界中发现的植被模式。我们给出了该模型的平均场和空间扩展版本的结果。我们发现，即使年总降水量（PPT）固定，模式也取决于雨季的持续时间，这表明季节性如何影响空间自组织。我们观察到，对于固定的PPT，生产力会随着持续时间而变化，从而提供了另一个观察到的变化来源。我们计算了最大植被覆盖度作为PPT的函数，发现其行为与观测结果一致。我们评论了气候变化导致的年际波动增加对生态系统状态转变的影响。我们的具体模型计算为因资源季节性变化而竞争稀缺资源的生态系统提供了更普遍的结论，特别是关于自组织和生产力方面。
