Loss of native vegetation cover in the watershed is known to affect stream fish communities. However, community response may not occur immediately after land cover change, and may become apparent only years later. In this study, we investigated how a c.a. 30-year (1985–2017) historical trajectory of native vegetation loss affected fish communities in 47 streams of southern Brazilian grasslands. We tested whether current species richness and composition would be more related to past or to recent natural vegetation cover. We then defined trajectories of vegetation loss and tested whether different attributes (frequency, magnitude and duration of disturbance) affected particular species and functional groups. We found that current species richness and composition were more related to past than to current vegetation cover. However, we also observed that responses of particular species and functional groups were dependent on specific trajectory attributes. We concluded that present fish community characteristics may respond not only to past watershed conditions but also to how watershed conditions have changed over the time. Exploring land use trajectories seems a promising approach for improving our understanding of landscape effects on stream ecosystems, as well as the predictability of present landscape management and planning on freshwater communities.

中文翻译：

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评估土地利用轨迹对巴西南部河流鱼类群落的影响

众所周知，流域中原生植被的丧失会影响溪流鱼类群落。然而，社区反应可能不会在土地覆盖变化后立即发生，并且可能在几年后才变得明显。在这项研究中，我们调查了大约 30 年（1985-2017）原生植被损失的历史轨迹如何影响巴西南部草原 47 条河流中的鱼类群落。我们测试了当前的物种丰富度和组成是否与过去或最近的自然植被覆盖更相关。然后，我们定义了植被损失的轨迹，并测试了不同的属性（干扰的频率、幅度和持续时间）是否影响了特定的物种和功能群。我们发现当前的物种丰富度和组成与过去的关系比与当前的植被覆盖有关。然而，我们还观察到特定物种和功能组的反应取决于特定的轨迹属性。我们得出的结论是，目前的鱼类群落特征可能不仅对过去的流域条件做出反应，而且对流域条件随时间的变化做出反应。探索土地利用轨迹似乎是一种很有前途的方法，可以提高我们对景观对河流生态系统影响的理解，以及对淡水社区当前景观管理和规划的可预测性。