Complex spatial patterns are common in coastal marine systems, but mechanisms underlying their formation are disputed. Most empirical work has focused on exogenous spatially structured disturbances as the leading cause of pattern formation in species assemblages. However, theoretical and observational studies suggest that complex spatial patterns, such as power laws in gap-size distribution, may result from endogenous self-organized processes involving local-scale interactions. The lack of studies simultaneously assessing the influence of spatially variable disturbances and local-scale interactions has fuelled the idea that exogenous and endogenous processes are mutually exclusive explanations of spatial patterns in marine ecosystems. To assess the relative contribution of endogenous and exogenous processes in the emergence of spatial patterns, an intertidal assemblage of algae was exposed for two years to various combinations of intensity and spatial patterns of disturbance. Localized disturbances impinging at the margins of previously disturbed clearings and homogenous disturbances without any spatial pattern generated heterogeneous distributions of disturbed gaps and macroalgal patches, characterized by a power-law scaling. Spatially varying disturbances produced a spatial gradient in the distribution of algal patches and, to a lesser extent, also a power-law scaling in both patch- and gap-size distributions. These results suggest that exogenous and endogenous processes are not mutually exclusive forces that can lead to the formation of similar spatial patterns in species assemblages.

中文翻译：

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外源性干扰和内源性自组织过程并不是大型藻类组合空间模式的相互排斥的驱动因素

复杂的空间模式在沿海海洋系统中很常见，但其形成的机制存在争议。大多数实证工作都集中在外源性空间结构干扰作为物种组合模式形成的主要原因。然而，理论和观察研究表明，复杂的空间模式，例如间隙大小分布的幂律，可能是由涉及局部尺度相互作用的内生自组织过程引起的。缺乏同时评估空间变量扰动和局部尺度相互作用的影响的研究助长了外源和内源过程是海洋生态系统空间模式相互排斥的解释的观点。评估内生和外生过程在空间模式出现中的相对贡献，潮间带藻类组合暴露于各种强度和空间干扰模式的组合中两年。冲击先前受干扰空地边缘的局部干扰和没有任何空间模式的同质干扰产生了受干扰间隙和大型藻类斑块的异质分布，以幂律标度为特征。空间变化的干扰在藻类斑块的分布中产生空间梯度，并且在较小程度上也在斑块和间隙大小分布中产生幂律缩放。这些结果表明，外源和内源过程并不是相互排斥的力量，可以导致在物种组合中形成相似的空间模式。