COLLABORATIVE RESEARCH: Temporal stability of riverine communities in dendritic networks at multiple spatial scales

了解物种群落如何随时间变化是生态学的基本目标之一。要理解自然系统是如何运作的，关键的一步是回答两个问题：1)为什么有些群落比其他群落对干扰更敏感？2)一个群落的敏感度可以根据它在景观中的位置来预测吗？这项研究试图了解社区是如何在河流中发展和维持的。具体地说，该项目将探索河流群落的敏感性如何受到环境特征的影响，这些环境特征决定了生物如何在景观中移动。这些环境特征的例子包括盛行的风流、森林碎片之间的联系以及河流的形状和分水岭中流入河流的小溪(即河流网络)。该项目使用河网中的溪流无脊椎动物作为模型系统。这项工作涉及三个主要任务：1)利用现有数据分析河网形状如何影响河流无脊椎动物群落的可变性水平。2)实验测试河网结构如何影响无脊椎动物群落对干扰的反应。这项任务将使用实验流来完成，通过实验诱导扰动，并跟踪响应。3)建立一个计算机模型，以探索考虑不同形状的网络、不同类型的生物和无法使用现有数据或实验探索的新干扰的情景。这项工作将直接向科学家和管理人员通报河流系统对干扰的反应。这项研究还将创造一个工具，用于探索新的河流系统中的网络。这项研究将为研究生和本科生提供生态学和数学建模方面的培训。将群落稳定性与可变环境中的空间过程联系起来是生态学剩余的巨大挑战之一，对生物多样性的管理和保护具有重要意义。研究人员将重点放在了对河流生态系统中无脊椎动物群落稳定性的控制上，因为他们发现，树枝状河流网络中的一个地点位置可以影响当地的生物多样性和时间稳定性。因此，这个项目解决了一个一般性的问题：一个群落在扩散网络中的位置如何与物种特征相互作用，以影响聚集和组成群落的稳定性？这项工作将建立在现有项目的基础上，包括河网生态、社区时间稳定性分析、河网建模以及模型与现场数据之间的相互作用。该项目将采用几种技术来解决这一问题，包括对存档的长期河流监测数据进行荟萃分析、现场实验和机械建模，以实现对观察到的成分和聚集稳定性背后的过程的理解，同时提供可移植到其他背景和系统的一般理论基础。最终，这项工作将针对三个具体问题：(1)在扩散网络中，位置如何影响群落的时间稳定性？(2)网络中不同位置的群落的弹性有多大？(3)局部稳定性和扩散网络的结构如何影响区域尺度上的稳定性，即整个扩散网络？

Understanding how communities of species change through time is one of the fundamental goals of ecology. A key step toward understanding how natural systems function is answering two questions: 1) Why are some communities more sensitive to disturbance than others? and 2) Can the sensitivity of a community be predicted based on its location in a landscape? This study seeks to understand how communities develop and are maintained in rivers. Specifically, the project will explore how sensitivity of river communities is affected by environmental features that dictate how organisms move about the landscape. Examples of these environmental features include prevailing wind currents, connections between forest fragments, and the shape of a river and the small streams feeding the river (i.e. river network) in a watershed. This project uses stream invertebrates in river networks as a model system. The work involves three major tasks: 1) To analyze how the shape of a river network affect the level of variability of stream invertebrate communities using existing data. 2) To experimentally test how the structure of river networks affects the response of invertebrate communities to disturbances. This task will be accomplished using experimental streams, experimentally inducing a disturbance, and following the response. 3) To produce a computer model to explore scenarios considering different shapes of networks, different types of organisms and novel disturbances that cannot be explored using existing data or experiments. This work will directly inform scientists and managers about the responses of river systems to disturbance. The study will also create a tool for exploration of networks in new river systems. This study will provide training for graduate and undergraduate students in ecology and mathematical modeling.Linking community stability to spatial processes in variable environments is one of ecology's remaining great challenges, with implications for the management and conservation of biodiversity. The researchers focus on controls over invertebrate community stability in riverine ecosystems because they have found that a site location in a dendritic stream network can influence both local biodiversity and temporal stability. Therefore, this project addresses the general question: How does location of a community within a dispersal network interact with species traits to affect aggregate and compositional community stability? The work will build on existing projects including the ecology of river networks, analysis of community temporal stability, river network modeling, and the interaction between models and field data. The project will employ several techniques to address the question, including a meta-analysis of archived long-term stream monitoring data, field experiments, and mechanistic modeling to achieve an understanding of processes behind observed compositional and aggregate stability while simultaneously providing a general theoretical underpinning that is transferable to other contexts and systems. Ultimately this work will be directed at three specific questions: (1) Within a dispersal network, how does location affect the temporal stability of communities? (2) How resilient are communities at different locations within a network? (3) How does local stability and structure of the dispersal network affect stability at the regional scale, i.e., across the entire dispersal network?