Material Cycling and the Stability of Ecosystems
Material Cycling and the Stability of Ecosystems
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物质循环与生态系统的稳定性
DOI：
10.1086/285616
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
M. Loreau
中科院分区：
文献类型：
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作者：
M. Loreau
以营养物形式存在的物质循环，如氮或磷，是每个生态系统不可或缺的一部分。因此，它通常包含在描述性生态系统模型中。然而，在大多数启发式理论模型中，它被忽视了，这些模型关注的是群落而不是生态系统（见，例如，1974年5月）。然而，关于养分循环对生态系统稳定性的影响，目前已经进行了大量的理论研究（Jordan等，1972; Austin和Cook，1974;韦伯斯特等，1975; Nisbet和Gurney，1976; Harwell等，1977，1981; Sjoberg，1977;帕克，1978; Harwell和Ragsdale，1979; DeAngelis，1980; Harrison and Fekete 1980; Nisbet et et al. 1983; DeAngelis et al. 1989 a; Nakajima and DeAngelis 1989）。DeAngelis及其同事最近对这些研究以及许多实证调查进行了广泛的综述（DeAngelis et al. 1989 b; DeAngelis 1992）。他们得出了以下结论：在物质封闭的模型生态系统中，物质循环增加了这些系统局部稳定的可能性，但物质循环程度的增加（即，在开放系统中，系统的封闭性增加会降低它们的弹性，也就是说，在扰动之后，它们返回到局部稳定的稳定状态的速率（DeAngelis等，1989 b）。DeAngelis（1980年）提供了一个特别清晰和普遍的证据，证明随着回收的加强，弹性会下降。然而，后一个结论似乎在某种程度上与前一个结论相矛盾：如果弹性随着更严格的回收而下降，封闭系统如何稳定？这似乎也与先驱生态学家的观点相矛盾，他们假设生态系统演替过程中更紧密的物质循环可能会增加体内平衡（Odum 1969）。这一悖论的部分解决方案在于这样一个事实，即弹性的下降可能伴随着阻力的增加（韦伯斯特等人，1975;哈里森和费克特，1980）。对干扰的抵抗力确实比恢复力更接近稳态的概念。我在这里的目的是更进一步，在封闭系统和开放系统的结论之间架起一座桥梁，并澄清迄今为止所研究的弹性的含义。我重新审视了DeAngelis（1980）使用的一般非线性模型，并表明弹性仅在有限意义上随着物质循环的加强而降低;也就是说，降低的只是生态系统内物质总量的弹性，而不是其内部结构的弹性。然后，我讨论了这一事实的含义。
The cycling of matter in the form of nutrients, such as nitrogen or phosphorus, is an integral part of every ecosystem. As such, it is usually included in descriptive ecosystem models. Yet it has been ignored in most heuristic theoretical models, which have focused on communities rather than ecosystems (see, e.g., May 1974). A number of theoretical studies, however, have now been carried out on the effect of nutrient cycling on ecosystem stability (Jordan et al. 1972; Austin and Cook 1974; Webster et al. 1975; Nisbet and Gurney 1976; Harwell et al. 1977, 1981; Sjoberg 1977; Parker 1978; Harwell and Ragsdale 1979; DeAngelis 1980; Harrison and Fekete 1980; Nisbet et al. 1983; DeAngelis et al. 1989a; Nakajima and DeAngelis 1989). These studies, as well as many empirical investigations, have recently been reviewed extensively by DeAngelis and colleagues (DeAngelis et al. 1989b; DeAngelis 1992). They have led to the following conclusions: material cycling in model ecosystems that are closed with respect to matter increases the probability that these systems will be locally stable, but an increased degree of material cycling (i.e., an increased closure of the system) in open systems decreases their resilience, that is, the rate at which they return to their locally stable, steady state following a perturbation (DeAngelis et al. 1989b). An especially clear and general demonstration of this tendency toward decreased resilience with tighter recycling was provided by DeAngelis (1980). The latter conclusion, however, seems to some extent to contradict he former: if resilience decreases with tighter recycling, how can closed systems be stable? It seems also to contradict the view of pioneer ecologists, who hypothesized that the tighter material cycling during the course of ecosystem succession might increase homeostasis (Odum 1969). A partial resolution of this paradox lies in the fact that a decrease in resilience may be accompanied by a concomitant increase in resistance (Webster et al. 1975; Harrison and Fekete 1980). Resistance to perturbations indeed approaches the concept of homeostasis much more than does resilience. My purpose here is to go further by laying a bridge between the conclusions from closed and open systems and clarifying the meaning of resilience as it has been investigated so far. I reexamine the general nonlinear model used by DeAngelis (1980) and show that resilience decreases with tighter material cycling only in a restricted sense; that is, what decreases is only the resilience of the total quantity of matter within the ecosystem, but not the resilience of its internal structure. I then discuss the implications of this fact.