Finnish Environment Institute, Natural Environment Centre, Ecosystem Change Unit, PO Box 413, FI-90014 Oulu, Finland.
Biol Rev Camb Philos Soc. 2013 Feb;88(1):166-78. doi: 10.1111/j.1469-185X.2012.00244.x. Epub 2012 Sep 3.
Most bioassessment programs rest on the assumption that species have different niches, and that abiotic environmental conditions and changes therein determine community structure. This assumption is thus equivalent to the species sorting perspective (i.e. that species differ in their responses to environmental variation) in metacommunity ecology. The degree to which basing bioassessment on the species sorting perspective is reasonable is likely to be related to the spatial extent of a study and the characteristics of the organism groups (e.g. dispersal ability) with which the effects of anthropogenic changes are assessed. Recent findings in metacommunity research have stressed that community structure is determined not only by local abiotic environmental conditions but also by biotic interactions and dispersal-related effects. For example, dispersal limitation may prevent community structure recovery from the effects of a putative stressor, as organisms may not be able to disperse to all sites in a region. Mass effects (i.e. the presence of species in environmentally suboptimal sites due to high dispersal rates from environmentally suitable sites) may, in turn, obscure the effects of a stressor, as dispersal from source sites (e.g. an unaltered site) allows persistence at sink sites (e.g. an anthropogenically altered site). Better bioassessment should thus take both niche- and dispersal-related processes simultaneously into consideration, which can be accomplished by explicitly modelling spatial location as a proxy for dispersal effects. Such an integrated approach should be included in bioassessment programs using general multivariate approaches, predictive modelling, and multimetric indices.
大多数生物评估计划都基于这样一种假设，即物种具有不同的生态位，生物环境条件及其变化决定了群落结构。因此，这一假设相当于后生境生态学中的物种分类观点（即物种对环境变化的响应存在差异）。基于物种分类观点进行生物评估的合理性程度可能与研究的空间范围以及所评估的生物体组（例如扩散能力）的特征有关。后生境研究的最新发现强调，群落结构不仅由当地的生物环境条件决定，还由生物相互作用和扩散相关的影响决定。例如，扩散限制可能会阻止群落结构从假定的胁迫因素的影响中恢复，因为生物可能无法扩散到一个区域的所有地点。大量效应（即由于高扩散率而导致物种存在于环境不利的地点）可能会掩盖胁迫因素的影响，因为源地点（例如未改变的地点）的扩散允许在汇地点（例如人为改变的地点）的持续存在。因此，更好的生物评估应该同时考虑与生态位和扩散相关的过程，可以通过明确将空间位置建模为扩散效应的代理来实现。这种综合方法应该包含在使用通用多元方法、预测模型和多指标指数的生物评估计划中。
