Department of Aquatic Ecology, University of Duisburg-Essen, 45117 Essen, Germany.
INRAE, UR RiverLy, EcoFlowS, F-69625 Villeurbanne, France.
Sci Total Environ. 2022 Apr 10;816:151590. doi: 10.1016/j.scitotenv.2021.151590. Epub 2021 Nov 12.
Woody riparian vegetation along rivers and streams provides multiple functions beneficial for aquatic macroinvertebrate communities. They retain fine sediments, nutrients and pesticides, improve channel hydromorphology, control water temperature and primary production through shading and provide leaves, twigs and large wood. In a recent conceptual model (Feld et al., 2018), woody riparian functions were considered either independent from large-scale landuse stressors (e.g. shading, input of organic matter), or dependent on landuse at larger spatial scales (e.g. fine sediment, nutrient and pesticide retention). We tested this concept using high-resolution data on woody riparian vegetation cover and empirical data from 1017 macroinvertebrate sampling sites in German lowland and mountain streams. Macroinvertebrate metrics indicative for individual functions were used as response variables in structural equation models (SEM), representing the hierarchical structure between the different considered stressors at different spatial scales: catchment, upstream riparian, local riparian and local landuse cover along with hydromorphology and water quality. The analysis only partly confirmed the conceptual model: Biotic integrity and water quality were strongly related to large-scale stressors as expected (absolute total effect 0.345-0.541), but against expectations, fine sediments retention, considered scale-dependent in the conceptual model, was poorly explained by large-scale stressors (absolute total effect 0.027-0.231). While most functions considered independent from large-scale landuse were partly explained by riparian landuse cover (absolute total effect 0.023-0.091) they also were nonetheless affected by catchment landuse cover (absolute total effect 0.017-0.390). While many empirical case studies at smaller spatial scales clearly document the positive effects of restoring woody riparian vegetation, our results suggest that most effects of riparian landuse cover are possibly superimposed by larger-scale stressors. This does not negate localized effects of woody riparian vegetation but helps contextualize limitations to successful restoration measures targeting the macroinvertebrate community.
河流和溪流的河岸植被提供了多种有益于水生大型无脊椎动物群落的功能。它们可以滞留细颗粒物质、养分和农药，改善河道形态，控制水温并通过遮荫进行初级生产，还可以提供叶子、树枝和大木头。在最近的概念模型中（Feld 等人，2018 年），河岸植被功能被认为要么独立于大规模土地利用压力源（如遮荫、有机质输入），要么依赖于更大空间尺度上的土地利用（如细颗粒物质、养分和农药的截留）。我们使用德国低地和山地溪流中 1017 个大型无脊椎动物采样点的高分辨率河岸植被覆盖数据和实证数据来检验这一概念。结构方程模型（SEM）中的响应变量是指示单个功能的大型无脊椎动物指标，代表不同空间尺度上不同考虑因素之间的层次结构：集水区、上游河岸、当地河岸和当地土地利用覆盖以及水力学形态和水质。分析结果仅部分证实了概念模型：生物完整性和水质与预期的大规模压力源密切相关（绝对总效应 0.345-0.541），但与预期相反，概念模型中认为依赖于尺度的细颗粒物质截留，被大规模压力源解释得很差（绝对总效应 0.027-0.231）。虽然大多数被认为独立于大规模土地利用的功能部分由河岸土地利用覆盖来解释（绝对总效应 0.023-0.091），但它们也受到集水区土地利用覆盖的影响（绝对总效应 0.017-0.390）。虽然在较小空间尺度上的许多实证案例研究清楚地记录了恢复河岸植被的积极影响，但我们的结果表明，河岸土地利用覆盖的大多数影响可能被更大规模的压力源所叠加。这并没有否定河岸植被的局部效应，而是有助于了解针对大型无脊椎动物群落的成功恢复措施的局限性。
