Upstream river morphology and riparian land use overrule local restoration effects on ecological status assessment
Upstream river morphology and riparian land use overrule local restoration effects on ecological status assessment
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上游河流形态和河岸土地利用推翻了当地恢复对生态状况评估的影响
作者：
A. Lorenz;C. Feld
河流恢复是当今流域管理的中心问题。不幸的是，许多研究表明有限的生态改善，假设集水区的影响和供体人口的缺失是主要的阻碍因素。根据上游汇水影响，对46条河段修复后的生态状况进行了评价。研究了三组环境参数：(i)河岸土地利用；（ii）恢复上游不同长度的自然生境质量；（iii）整个流域上游的土地利用。以标准化鱼类、无脊椎动物和大型植物样品的生态质量比作为响应变量。结果表明，子流域变量对生态状况的影响大于局部栖息地改善。其中，鱼类和无脊椎动物生态状况与上游落叶林百分比呈正相关，而大型植物生态状况与上游落叶林百分比呈正相关。此外，我们还发现，在修复上游5 km范围内，站点尺度的生态状况与自然栖息地质量之间存在很强的联系；上游河岸土地利用和河流生境质量越自然，恢复河段生态质量越好。我们的结论是，如果上游的子集水区物理栖息地退化，则站点尺度的恢复措施可能会失败。
River restoration is a central issue of present-day River Basin Management. Unfortunately, many studies have shown limited ecological improvements, hypothesizing catchment influences and missing donor populations as main impeding factors. This study evaluates the ecological status after restoration at 46 river reaches in light of catchment influences upstream. Three groups of environmental parameters were investigated: (i) riparian land use and (ii) physical habitat quality in different lengths upstream of the restorations and (iii) land use in the whole catchment upstream. Ecological quality ratios of standardized fish, invertebrate and macrophyte samples were used as response variables. The results imply that sub-catchment variables influence the ecological status more than local habitat improvements. In particular, fish and invertebrate ecological status was positively linked to percent deciduous forest upstream of restored sites, while macrophytes revealed an opposite trend. Furthermore, we found a strong linkage of site-scale ecological status and physical habitat quality up to 5 km upstream of the restorations; the more natural were riparian land use and river habitat quality upstream, the higher was the chance of a good ecological quality in restored reaches. We conclude that site-scale restoration measures are likely to be unsuccessful, if the sub-catchment physical habitat upstream is degraded.