Using macroinverteb rates to identify biota-land cover optima at multiple scales in the Pacific Northwest, USA
Using macroinverteb rates to identify biota-land cover optima at multiple scales in the Pacific Northwest, USA
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DOI：
10.1899/0887-3593(2004)023
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发表时间：
2004-06-01
影响因子：
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通讯作者：
Plotnikoff, RW
中科院分区：
文献类型：
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作者：
Black, RW;Munn, MD;Plotnikoff, RW
对美国华盛顿州普吉特海湾盆地的 45 个溪流地点的大型无脊椎动物群落和环境变量进行了评估。环境变量在 3 个空间尺度上进行测量：范围、局部和整个流域。使用典型对应分析将大型无脊椎动物分布与环境变量相关，以确定哪些变量和空间尺度最能解释观察到的群落组成，并确定生物群-土地覆盖最佳值。生物群-土地覆盖最佳值的计算过程分为两步。首先，通过对所有地点该分类单元的丰度加权该土地覆盖的平均值来估计特定土地覆盖的单个分类单元的最佳值。其次，生物群-土地覆盖最佳值被确定为特定土地覆盖在计算出的最佳值下出现最大数量的类群的点。采样河段位于流域内的溪流上，具有不同程度的森林、农业和城市/郊区土地覆盖，代表了普吉特湾溪流中常见的全部物理条件。在河段尺度上，类群组成与电导率和平均速度相关。在局部和整个流域尺度上，类群组成分别与森林和农业土地覆盖百分比以及森林和基岩土地覆盖百分比相关。对于所有尺度，主要的环境变量代表了人为梯度。每个空间尺度解释的变异量几乎没有差异。在当地流域范围内，确定了类似于 80% 至 90% 的森林土地覆盖的最佳生物群土地覆盖。随着当地范围内的林地覆盖率下降到80％至90％以下，最佳时的类群总数迅速下降。在整个流域尺度上，确定了 70% 至 80% 森林土地覆盖的最佳生物群土地覆盖。随着整个流域内的森林土地覆盖率下降到 70% 至 80% 以下，最佳状态下的类群总数迅速下降。我们的结果表明，大型无脊椎动物既可以用作多个尺度环境条件的定量指标，也可以用作土地覆盖最佳指标。对这些最佳方案的进一步检查可用于确定保护和恢复工作的优先事项。
Macroinvertebrate assemblages and environmental variables were evaluated at 45 stream sites throughout the Puget Sound Basin, Washington, USA. Environmental variables were measured at 3 spatial scales: reach, local, and whole watershed. Macroinvertebrate distributions were related to environmental variables using canonical correspondence analysis to determine which variables and spatial scales best explained the observed community composition and to identify biota-land cover optima. The calculation of a biota-land cover optimum was a 2-step process. First, an individual taxon's optimum was estimated for a particular land cover by weighting the mean value for that land cover by the abundance of that taxon at all sites. Second, the biota-land cover optimum was determined as the point at which the greatest numbers of taxa, at their calculated optima, appeared for a particular land cover. Sampling reaches were located on streams in watersheds with varying levels of forest, agriculture, and urban/suburban land cover that represented the full range of physical conditions typically found in Puget Sound streams. At the reach scale, taxa composition was correlated with conductivity and mean velocity. At the local and whole-watershed scales, taxa composition was correlated with % forest and agricultural land cover and % forest and bedrock land cover, respectively. For all of the scales, the dominant environmental variables represented an anthropogenic gradient. There was little difference in the amount of variability explained by each spatial scale. At the local-watershed scale, a biota-land cover optimum of similar to80 to 90% forest land cover was identified. The total number of taxa at their optima declined rapidly as forest land cover within the local scale declined below 80 to 90%. At the whole-watershed scale, a biota-land cover optimum of 70 to 80% forest land cover was identified. The total number of taxa at their optima declined rapidly as forest land cover within the whole watershed declined below 70 to 80%. Our results suggest that macroinvertebrates can be used both as quantitative indicators of environmental conditions at multiple scales and indicators of land cover optima. Further examination of these optima could be used to establish priorities for conservation and restoration efforts.