Institute for Fisheries Research, Michigan Department of Natural Resources, University of Michigan, 1109 N University, Ann Arbor, MI 48109, USA.
Environ Manage. 2012 Nov;50(5):875-87. doi: 10.1007/s00267-012-9938-y. Epub 2012 Sep 8.
Identifying appropriate spatial scales is critically important for assessing health, attributing data, and guiding management actions for rivers. We describe a process for identifying a three-level hierarchy of spatial scales for Michigan rivers. Additionally, we conduct a variance decomposition of fish occurrence, abundance, and assemblage metric data to evaluate how much observed variability can be explained by the three spatial scales as a gage of their utility for water resources and fisheries management. The process involved the development of geographic information system programs, statistical models, modification by experienced biologists, and simplification to meet the needs of policy makers. Altogether, 28,889 reaches, 6,198 multiple-reach segments, and 11 segment classes were identified from Michigan river networks. The segment scale explained the greatest amount of variation in fish abundance and occurrence, followed by segment class, and reach. Segment scale also explained the greatest amount of variation in 13 of the 19 analyzed fish assemblage metrics, with segment class explaining the greatest amount of variation in the other six fish metrics. Segments appear to be a useful spatial scale/unit for measuring and synthesizing information for managing rivers and streams. Additionally, segment classes provide a useful typology for summarizing the numerous segments into a few categories. Reaches are the foundation for the identification of segments and segment classes and thus are integral elements of the overall spatial scale hierarchy despite reaches not explaining significant variation in fish assemblage data.
确定适当的空间尺度对于评估河流的健康状况、归因数据以及指导管理行动至关重要。我们描述了一种为密歇根州河流确定三级空间尺度层次结构的过程。此外，我们对鱼类出现、丰度和集合度量数据进行方差分解，以评估三个空间尺度可以解释多少观测到的变异性，以此衡量其在水资源和渔业管理中的效用。该过程涉及开发地理信息系统程序、统计模型、经验丰富的生物学家的修改以及简化，以满足政策制定者的需求。总共有 28889 个河段、6198 个多河段段和 11 个河段类别从密歇根河流网络中确定。在鱼类丰度和出现方面，段尺度解释了最大的变异，其次是段类别和河段。在 19 个分析的鱼类集合指标中，有 13 个指标的段尺度解释了最大的变异，而另外 6 个鱼类指标的段类别解释了最大的变异。段似乎是一个有用的空间尺度/单位，用于测量和综合管理河流和溪流的信息。此外，段类别为将众多段概括为几个类别提供了有用的分类法。河段是识别段和段类别的基础，因此尽管河段不能解释鱼类集合数据的显著变化，但它们仍然是整个空间尺度层次结构的组成部分。
