ISAC-CNR, C.so Fiume 4, 10133 Torino, Italy.
Proc Biol Sci. 2010 Jun 7;277(1688):1771-6. doi: 10.1098/rspb.2009.2208. Epub 2010 Feb 4.
Two major forms of vegetation patterns have been observed in drylands: nearly periodic patterns with characteristic length scales, and amorphous, scale-free patterns with wide patch-size distributions. The emergence of scale-free patterns has been attributed to global competition over a limiting resource, but the physical and ecological origin of this phenomenon is not understood. Using a spatially explicit mathematical model for vegetation dynamics in water-limited systems, we unravel a general mechanism for global competition: fast spatial distribution of the water resource relative to processes that exploit or absorb it. We study two possible realizations of this mechanism and identify physical and ecological conditions for scale-free patterns. We conclude by discussing the implications of this study for interpreting signals of imminent desertification.
具有特征长度尺度的近乎周期性模式，以及具有广泛斑块大小分布的无定形、无标度模式。无标度模式的出现归因于对有限资源的全球竞争，但这一现象的物理和生态起源尚不清楚。使用一个用于水限制系统中植被动态的空间显式数学模型，我们揭示了一个用于全球竞争的一般机制：相对于利用或吸收水资源的过程，水资源的快速空间分布。我们研究了这个机制的两种可能实现，并确定了无标度模式的物理和生态条件。最后，我们讨论了这项研究对解释即将发生的荒漠化信号的意义。
