Geomorphic Complexity as a Disturbance Modifier

目前的理论表明，生态系统的稳定性是物理和生物复杂性的函数。频繁的扰动可能会降低这种复杂性，从而破坏生态系统的稳定，使它们更容易受到未来扰动的影响。理论预测，具有大尺度物理(即地貌)复杂性的生态系统在受到灾难性扰动的影响时，能够有效地保持结构的完整性。该项目将开发一个量化模型，将干扰导致的生态系统结构复杂性的变化与稳定性联系起来。由于河流受景观地貌的影响很大，对干扰的反应相对较快，因此将使用河流生态系统。将根据伐木影响、山体滑坡和洪水对一般河流生态系统动态的干扰-稳定性关系进行评估，特别强调鱼类种群的反应。为了解决大小尺度物理复杂性的重要性，模型将采用分层结构(即包含流域、河流段和河道单元尺度)，并侧重于考察河流段尺度上的采伐影响。利用该模型开发和评估的假说应该为地貌复杂性如何与干扰生态系统结构相互作用提供新的见解，并为生物成分的成功或失败奠定基础。

Current theory suggests that ecosystem stability is a function of physical and biological complexity. Frequent disturbances may reduce this complexity and thereby destabilize ecosystems, making them more susceptible to future perturbations. Theory predicts that ecosystems with large scale physical (i.e. geomorphic) complexity can effectively maintain structural integrity when impacted by catastrophic disturbances. This project will develop a quantitative model that links changes in ecosystem structural complexity resulting from disturbances, to stability. Because streams are strongly influenced by landscape geomorphology and respond relatively quickly to disturbances, stream ecosystems will be used. Disturbance-stability relationships will be assessed in terms of logging impacts, landslides, and floods on general stream ecosystem dynamics, with special emphasis on fish population responses. To address the importance of large and small scale physical complexity, the model will be hierarchically structured (i.e. contain basin, stream reach, and channel unit scales), and focus on examination of logging impacts at the stream reach scale. Hypotheses developed and evaluated with this model should provide new insights into how geomorphic complexity interacts with disturbance to structure ecosystems and set the stage for the success or failure of biotic components.