Paavola Riku, Muotka Timo, Virtanen Risto, Heino Jani, Jackson Donald, Maki-Petäys Aki
Department of Zoology, University of Toronto, Toronto, Ontario M5S 3G5 Canada.
Ecol Appl. 2006 Feb;16(1):368-79. doi: 10.1890/03-5410.
Owing to the lack of information about the distribution patterns of many taxonomic groups, biodiversity conservation strategies commonly rely on a surrogate taxa approach for identifying areas of maximum conservation potential. Macroinvertebrates or fish are the most likely candidates for such a role in many freshwater systems. The usefulness of the surrogate taxa depends largely on community concordance, i.e., the degree of similarity in community patterns among taxonomic groups across a set of sites. We examined the effect of the spatial scale of a. study on the strength of community concordance among macroinvertebrates, bryophytes, and fish by comparing the concordance between ordinations of these groups in 101 boreal stream sites. We specifically asked if communities spanning several drainages are more concordant than those originating from a single drainage system. Our results indicate that community concordance is affected by spatial extent, being variable and generally weak at the scale of individual drainages, but strong across multiple drainage systems and ecoregions. We attribute this finding to different taxonomic groups responding to similar environmental factors and sharing a similar latitudinal gradient of community structure when viewed across large spatial scales. We also identified a "gradient of concordance," with sites contributing disproportionately to community concordance being in relatively large streams with high microhabitat variability. Overall, our results suggest that the degree of community concordance among freshwater organism groups depends critically on the spatial extent of the study, and surrogate groups at the scale of single river systems should be used with caution.
由于缺乏许多分类群分布模式的信息，生物多样性保护策略通常依靠替代分类单元方法来确定具有最大保护潜力的区域。在许多淡水系统中，大型无脊椎动物或鱼类最有可能充当这一角色。替代分类单元的有效性在很大程度上取决于群落一致性，即一组地点的分类群之间群落模式的相似程度。我们通过比较101个北方溪流地点这些类群的排序之间的一致性，研究了研究空间尺度对大型无脊椎动物、苔藓植物和鱼类群落一致性强度的影响。我们特别询问跨越多个排水区域的群落是否比源自单一排水系统的群落更具一致性。我们的结果表明，群落一致性受空间范围的影响，在单个排水区域尺度上是可变的且通常较弱，但在多个排水系统和生态区域中较强。我们将这一发现归因于不同的分类群对相似环境因素做出反应，并且在大空间尺度上观察时共享相似的群落结构纬度梯度。我们还确定了一个 “一致性梯度”，对群落一致性贡献不成比例的地点位于具有高微生境变异性的相对较大溪流中。总体而言，我们的结果表明，淡水生物类群之间的群落一致性程度严重取决于研究的空间范围，并且在单一河流系统尺度上使用替代类群时应谨慎。
