Institut Català de Ciències del Clima (IC3), C/Dr. Trueta 203, 08005 Barcelona, Catalonia, Spain.
Ecol Lett. 2010 Jul;13(7):793-802. doi: 10.1111/j.1461-0248.2010.01497.x. Epub 2010 Jun 7.
We test for two critical phenomena in Amazonian ecosystems: self-organized criticality (SOC) and critical transitions. SOC is often presented in the complex systems literature as a general explanation for scale invariance in nature. In particular, this mechanism is claimed to underlie the macroscopic structure and dynamics of terrestrial ecosystems. These would be inextricably linked to the action of fire, which is conceived as an endogenous ecological process. We show that Amazonian savanna fires display the scale-invariant features characteristic of SOC but do not display SOC. The same is true in Amazonian rainforests subject to moderate drought. These findings prove that there are other causes of scale invariance in ecosystems. In contrast, we do find evidence of a critical transition to a megafire regime under extreme drought in rainforests; this phenomenon is likely to determine the time scale of a possible loss of Amazonian rainforest caused by climate change.
自组织临界性（SOC）和临界转变。SOC 在复杂系统文献中常被作为自然界中尺度不变性的一般解释。具体来说，这种机制据称是陆地生态系统宏观结构和动态的基础。这些将与火的作用紧密相关，火被认为是一种内生的生态过程。我们表明，亚马逊稀树草原火灾表现出 SOC 的特征，但没有表现出 SOC。在受到中度干旱影响的亚马逊雨林中也是如此。这些发现证明，生态系统中存在其他导致尺度不变性的原因。相比之下，我们确实在雨林中极端干旱下发现了向大火模式临界转变的证据；这种现象可能决定了气候变化可能导致亚马逊雨林消失的时间尺度。
