1. Landscape homogenization and the removal of riparian areas have altered stream ecosystems worldwide. Numerous conservation programmes attempt to improve water quality and increase instream habitat heterogeneity to elicit desired biological responses. However, the effectiveness of many conservation efforts on isolated stream fragments remains unknown, especially in grassland regions.
2. The effects of grassland conservation practices and the re-establishment of riparian corridors in the James River basin, South Dakota (USA) on stream water quality, habitat availability and aquatic macroinvertebrate and fish assemblages were studied in an agriculturally dominated prairie landscape.
3. Grassland conservation efforts may have repaired riparian condition, reduced turbidity and created more diverse instream habitat complexes at conservation sites based on comparisons with paired reference reaches. Reference sites were relatively homogeneous, with prevalent siltation, bank erosion and disturbances to the riparian vegetation. Owing to significant riparian vegetation development, overhanging and aquatic vegetation, benthic detritus and woody materials were significantly more common at conservation reaches.
4. Restoration efforts that assume ‘if you (re-)build it, they will come’ (i.e. the ‘field of dreams’ hypothesis) underestimate other important barriers to biodiversity restoration in dynamic, grassland riverscapes. Although aquatic organisms in grassland ecosystems are adapted to rapidly inhabit available habitats, the development of niche space at conservation reaches did not directly result in colonization by aquatic life.
5. Grassland management actions did not address stream connectivity issues or overcome land use influences elsewhere in the riverscape that may govern the responses of aquatic macroinvertebrates and fish. Stream fragmentation and continuing, damaging land use patterns seemed to exceed the positive effects of restoring isolated stream reaches in these heavily degraded catchments. Catchment-scale management strategies that combine reach-level restoration actions with efforts to improve connectivity are likely to be more successful in degraded riverscapes.

中文翻译：

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水生生态系统对邻近草原保护的局部反应：在退化的河流景观中能否存在梦想之流？

1. 景观同质化和河岸地区的移除改变了全世界的河流生态系统。许多保护计划试图改善水质并增加河内栖息地的异质性，以引发所需的生物反应。然而，许多对孤立河流片段的保护工作的有效性仍然未知，尤其是在草原地区。
2. 在以农业为主的草原景观中，研究了草原保护做法和重建南达科他州詹姆斯河流域河岸走廊对溪流水质、栖息地可用性以及水生大型无脊椎动物和鱼类组合的影响。
3. 根据与成对参考河段的比较，草原保护工作可能已经修复了河岸状况，降低了浊度，并在保护地点创造了更多样化的河内栖息地复合体。参考地点相对均质，具有普遍的淤积、河岸侵蚀和对河岸植被的干扰。由于河岸植被显着发育，悬垂和水生植被、底栖碎屑和木质材料在保护区更为常见。
4. 假设“如果你（重新）建造它，他们就会来”（即“梦想领域”假设）的恢复工作低估了动态草原河流景观中生物多样性恢复的其他重要障碍。尽管草原生态系统中的水生生物适应了快速栖息于现有的栖息地，但保护区内生态位空间的发展并没有直接导致水生生物的定居。
5. 草地管理行动没有解决河流连通性问题或克服河流景观其他地方的土地利用影响，这些影响可能控制水生大型无脊椎动物和鱼类的反应。在这些严重退化的集水区，河流破碎和持续的破坏性土地利用模式似乎超过了恢复孤立的河流河段的积极影响。将河段恢复行动与改善连通性的努力相结合的流域规模管理策略在退化的河流景观中可能会更成功。