Abstract Riparian land use is a key driver of stream ecosystem processes but its effects on water quality are still a matter of debate when proposing measures to improve freshwater quality. The aim of this study was to examine the influence of riparian land use on stream habitat and water chemistry, and to assess in what extent stream habitat also affects water quality. To that end, we selected eight reaches in the Ave River basin (northwestern Portugal) and compared longitudinal variations in water chemistry and stream habitat between reaches with different land use (urban, agricultural and natural), and between reaches with natural riparian areas and different habitats. Stream habitat was assessed using the Fluvial Functional Index, the HABSCORE, and the Riparian Forest Quality Index. Longitudinal variations in water chemistry were determined measuring differences in concentrations of ammonium, nitrate, phosphate and oxygen, and conductivity, pH and temperature between the downstream and the upstream ends of each reach. Nitrate concentration tended to decrease along reaches with more natural riparian areas and to increase along reaches with more urban and agricultural land uses. Longitudinal variations in water chemistry also differed between reaches with natural riparian areas, suggesting that water quality also depends on stream habitat. Moreover, longitudinal variation in water chemistry was proven a simple, useful and low-cost approach to assess the influence of land cover and stream habitat on water quality. Overall results demonstrated that both riparian land use and stream habitat influence water quality and that riparian forests are essential to reduce nutrient export to downstream ecosystems.

中文翻译：

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河岸土地利用和河流栖息地调节水质

摘要 河岸土地利用是河流生态系统过程的关键驱动因素，但在提出改善淡水质量的措施时，其对水质的影响仍然存在争议。本研究的目的是检查河岸土地利用对河流栖息地和水化学的影响，并评估河流栖息地对水质的影响程度。为此，我们选择了 Ave 河流域（葡萄牙西北部）的八个河段，并比较了不同土地利用（城市、农业和自然）河段之间以及具有自然河岸区和不同河段的河段之间水化学和河流栖息地的纵向变化。栖息地。河流栖息地使用河流功能指数、HABSCORE 和河岸森林质量指数进行评估。水化学的纵向变化是通过测量铵、硝酸盐、磷酸盐和氧气的浓度差异以及每个河段下游和上游端之间的电导率、pH 值和温度的差异来确定的。硝酸盐浓度倾向于随着自然河岸地区的增加而降低，而随着城市和农业用地使用量的增加而增加。水化学的纵向变化在具有自然河岸地区的河段之间也不同，这表明水质还取决于溪流栖息地。此外，水化学的纵向变化被证明是一种评估土地覆盖和河流栖息地对水质影响的简单、有用和低成本的方法。