A theoretical foundation for multi-scale regular vegetation patterns
A theoretical foundation for multi-scale regular vegetation patterns
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DOI：
10.1038/nature20801
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发表时间：
2017-01-19
期刊：
影响因子：
64.8
通讯作者：
Pringle, Robert M.
中科院分区：
文献类型：
--
作者：
Tarnita, Corina E.;Bonachela, Juan A.;Pringle, Robert M.
自组织的规则植被模式广泛存在(1)，并被认为调节生态系统功能，如生产力和稳健性（2-4），但其起源和维持的机制仍存在争议。特别有争议的是过度分散（均匀间隔）元素的景观，如北美的Mima土丘，巴西的murundus，南非的heuweltjies，以及著名的纳米比亚仙女圈（5-13）。目前有两种相互竞争的假设在争论。一方面，尺度依赖反馈模型，即植物在与远处个体竞争的同时促进邻居，可以再现卫星图像中识别的各种规则模式（1,14,15）。由于其深厚的理论基础和明显的普遍性，尽管缺乏经验证据（18），但尺度依赖反馈被广泛视为规则模式形成的统一和近乎普遍的原则（1,16,17）。另一方面，世界范围内许多过度分散的植被模式被归因于地下生态系统工程师，如白蚁、蚂蚁和啮齿动物（3,4,7,19-22）。尽管这种解释可能与领土竞争相一致（19-21,23,24），但在理论上和经验上都受到了挑战（11,17,24-26），而且（与依赖尺度的反馈不同）缺乏统一的动力学理论，这使人们对其合理性和普遍性产生了怀疑（5,9-11,16-18,24-26）。本研究为群居昆虫群体的自组织提供了一般性的理论基础，并通过四大洲的数据验证了这一理论的有效性，证明了领地动物之间的种内竞争可以产生这些模式的大规模六边形规则。然而，这种机制与依赖于尺度的反馈并不相互排斥。以纳米布沙漠仙女圈为例，我们提供的实地数据表明，这些景观呈现出多尺度模式——以前在该系统中没有记录——不能单独用任何一种机制来解释。在我们的理论框架中，这些多尺度模式和其他突发性特性，如增强的抗旱性和从干旱中恢复，是由两种机制耦合的动态相互作用产生的。潜在的全球范围内动物诱导的植被规律——它可以以重要的功能方式调节其他模式过程——强调了整合多种生态自组织机制的必要性（27）。
Self-organized regular vegetation patterns are widespread(1) and thought to mediate ecosystem functions such as productivity and robustness(2-4), but the mechanisms underlying their origin and maintenance remain disputed. Particularly controversial are landscapes of overdispersed (evenly spaced) elements, such as North American Mima mounds, Brazilian murundus, South African heuweltjies, and, famously, Namibian fairy circles(5-13). Two competing hypotheses are currently debated. On the one hand, models of scale-dependent feedbacks, whereby plants facilitate neighbours while competing with distant individuals, can reproduce various regular patterns identified in satellite imagery(1,14,15). Owing to deep theoretical roots and apparent generality, scale-dependent feedbacks are widely viewed as a unifying and near-universal principle of regular-pattern formation(1,16,17) despite scant empirical evidence(18). On the other hand, many overdispersed vegetation patterns worldwide have been attributed to subterranean ecosystem engineers such as termites, ants, and rodents(3,4,7,19-22). Although potentially consistent with territorial competition(19-21,23,24), this interpretation has been challenged theoretically and empirically(11,17,24-26) and (unlike scale-dependent feedbacks) lacks a unifying dynamical theory, fuelling scepticism about its plausibility and generality(5,9-11,16-18,24-26). Here we provide a general theoretical foundation for self-organization of social-insect colonies, validated using data from four continents, which demonstrates that intraspecific competition between territorial animals can generate the large-scale hexagonal regularity of these patterns. However, this mechanism is not mutually exclusive with scale-dependent feedbacks. Using Namib Desert fairy circles as a case study, we present field data showing that these landscapes exhibit multi-scale patterning-previously undocumented in this system-that cannot be explained by either mechanism in isolation. These multi-scale patterns and other emergent properties, such as enhanced resistance to and recovery from drought, instead arise from dynamic interactions in our theoretical framework, which couples both mechanisms. The potentially global extent of animal-induced regularity in vegetation-which can modulate other patterning processes in functionally important ways-emphasizes the need to integrate multiple mechanisms of ecological self-organization(27).