Fragility of stream ecosystem functioning in response to drought: an experimental test

预计气候变化和人类活动将改变进入河流和溪流的水量，对生活在这些生态系统中的动植物产生潜在的巨大影响。在许多地区，气候变化预计将减少降雨并带来干旱条件，而取水和河流改道也可能减少河流和溪流的流量。迄今为止，在确定水文干旱对水生生物多样性的影响方面所做的工作相对较少，对影响水质和水生生物生产力的重要过程，如分解和养分循环的影响所知较少。我们的研究将采用新颖的实验来了解河流水文干旱的生态效应，以期预测未来的变化。我们将使用一系列人工河道来直接操纵流量，从而模拟干旱事件，并测量动植物的反应，以及一系列反映生态系统生态健康的过程。我们将建立一系列在流量减少程度上不同的实验性干旱处理，从不变的参考条件到导致栖息地丧失的极低流量。我们还将研究河床的物理性质如何影响动物和植物承受干旱时期的程度，以及这些群落从这些事件中恢复的速度。与一名项目学生一起，我们将调查水的抽取是如何影响生物多样性和英格兰西南部一系列低地河流的功能的，这是导致河流干旱的主要人为原因。总之，这些结果将对环境对人类活动带来的变化的反应方式和气候变化的可能影响提供有价值的见解。

Climate change and human activities are expected to change the quantity of water entering rivers and streams, with potentially dramatic impacts on animals and plants resident in these ecosystems. In many regions, climate change is expected to reduce rainfall and bring about drought conditions, and water abstraction and river diversions may also reduce flows in rivers and streams. To date, relatively little work has been done to determine the effect of hydrologic droughts on aquatic biodiversity, and less is known about impacts on important processes, such as decomposition and nutrient cycling, that affect water quality and productivity of aquatic life.Our study will use novel experiments to understand the ecological effects of hydrologic droughts in streams, with a view to predicting future change. We will use a series of artificial stream channels to directly manipulate flows, thereby simulating drought episodes, and measure the responses of flora and fauna, and a series of processes that reflect the ecological health of the ecosystem. We will establish a series of experimental drought treatments which differ in the extent of flow reduction, from unaltered reference conditions to extreme low flows that cause habitat loss. We will also examine how the physical nature of the stream bed affects the extent to which animals and plants can withstand periods of drought, and how quickly these communities recover from these events. With a project student, we will investigate how water abstraction, a leading anthropogenic cause of stream drought, affects biodiversity and functioning across a suite of lowland streams in south west England. Together, the results will give valuable insights into the ways in which the environment responds to change brought about through human activities and the likely effects of climate change.