van de Koppel Johan, van der Wal Daphne, Bakker Jan P, Herman Peter M J
Centre for Estuarine and Marine Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 140, 4400 AC Yerseke, The Netherlands.
Am Nat. 2005 Jan;165(1):E1-12. doi: 10.1086/426602. Epub 2004 Nov 9.
Complexity theory predicts that local feedback processes may strongly affect the organization of ecosystems on larger spatial scales. Whether complexity leads to increased resilience and stability or to increased vulnerability and criticality remains one of the dominant questions in ecology. We present a combined theoretical and empirical study of complex dynamics in mineralogenic salt marsh ecosystems that emerge from a positive feedback between clay accumulation and plant growth. Positive feedback induces self-organizing within the ecosystem, which buffers for the strong physical gradient that characterizes the marine-terrestrial boundary, and improves plant growth along the gradient. However, as a consequence of these self-organizing properties, salt marshes approach a critical state as the edge of the salt marsh and the adjacent intertidal flat becomes increasingly steep and vulnerable to wave attack. Disturbance caused, for instance, by a storm may induce a cascade of vegetation collapse and severe erosion on the cliff edge, leading to salt marsh destruction. Our study shows that on short timescales, self-organization improves the functioning of salt marsh ecosystems. On long timescales, however, self-organization may lead to destruction of salt marsh vegetation.
复杂性理论预测，局部反馈过程可能会在更大的空间尺度上强烈影响生态系统的组织。复杂性究竟会导致恢复力和稳定性增强，还是会导致脆弱性和临界性增加，仍然是生态学中的主要问题之一。我们对成矿盐沼生态系统中的复杂动态进行了一项理论与实证相结合的研究，这种复杂动态源于粘土积累与植物生长之间的正反馈。正反馈在生态系统内引发自组织，这种自组织缓冲了表征海陆边界的强烈物理梯度，并沿着该梯度改善了植物生长。然而，由于这些自组织特性，随着盐沼边缘和相邻潮间带滩涂变得越来越陡峭且易受海浪侵袭，盐沼接近临界状态。例如，风暴引起的干扰可能引发一连串的植被崩塌以及悬崖边缘的严重侵蚀，导致盐沼遭到破坏。我们的研究表明，在短时间尺度上，自组织改善了盐沼生态系统的功能。然而，在长时间尺度上，自组织可能导致盐沼植被遭到破坏。
