Vulnerability of stream community composition and function to projected thermal warming and hydrologic change across ecoregions in the western United States
Vulnerability of stream community composition and function to projected thermal warming and hydrologic change across ecoregions in the western United States
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DOI：
10.1111/gcb.13437
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发表时间：
2017-01
影响因子：
11.6
通讯作者：
Matthew I. Pyne;N. L. Poff
中科院分区：
文献类型：
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作者：
Matthew I. Pyne;N. L. Poff
溪流生态系统中生物多样性和生态过程对快速气候变化的反应将取决于数量和功能上占优势的水生昆虫物种对溪流温度和水文变化的反应。在美国西部的8个生态区的253个最小扰动流，我们模拟了88个昆虫类群的分布与现有的最高夏季温度，平均年径流量的组合，以及它们之间的相互作用。我们使用了热图方法沿着与缩小尺度的大气环流模型（GCM）预测变暖和径流变化，以估计每个分类群的特定地点灭绝可能性，从而可以估计这些生态区溪流中的整个群落变化。保守的气候变化预测表明，30-40%的物种损失在温暖，干燥的生态区和10-20%的损失在凉爽，潮湿的生态区，物种相对缓冲从预计的变暖和水文变化。在处理基础资源方面具有关键功能觅食作用的类群的差异脆弱性表明，气候变化有可能改变河流营养结构和功能（例如，改变碎屑分解和藻类消耗的速度），特别是在温暖和干燥的生态区。我们表明，径流变化是同样重要的预测风险流社区组成的变暖，这两个基本的驱动程序所构成的相对威胁各不相同，根据预测的温度梯度和水文变化的生态区。结果还表明，直接人类修改流通过行动，如取水可能会进一步加剧损失的类群和生态系统的改变，特别是在干燥的气候。由于昆虫敏感性的地理差异以及对预计的热变暖和水文变化的暴露，减轻气候变化对河流生态系统的影响或积极适应这些影响的管理行动将需要区域校准。
Shifts in biodiversity and ecological processes in stream ecosystems in response to rapid climate change will depend on how numerically and functionally dominant aquatic insect species respond to changes in stream temperature and hydrology. Across 253 minimally perturbed streams in eight ecoregions in the western USA, we modeled the distribution of 88 individual insect taxa in relation to existing combinations of maximum summer temperature, mean annual streamflow, and their interaction. We used a heat map approach along with downscaled general circulation model (GCM) projections of warming and streamflow change to estimate site‐specific extirpation likelihood for each taxon, allowing estimation of whole‐community change in streams across these ecoregions. Conservative climate change projections indicate a 30–40% loss of taxa in warmer, drier ecoregions and 10–20% loss in cooler, wetter ecoregions where taxa are relatively buffered from projected warming and hydrologic change. Differential vulnerability of taxa with key functional foraging roles in processing basal resources suggests that climate change has the potential to modify stream trophic structure and function (e.g., alter rates of detrital decomposition and algal consumption), particularly in warmer and drier ecoregions. We show that streamflow change is equally as important as warming in projected risk to stream community composition and that the relative threat posed by these two fundamental drivers varies across ecoregions according to projected gradients of temperature and hydrologic change. Results also suggest that direct human modification of streams through actions such as water abstraction is likely to further exacerbate loss of taxa and ecosystem alteration, especially in drying climates. Management actions to mitigate climate change impacts on stream ecosystems or to proactively adapt to them will require regional calibration, due to geographic variation in insect sensitivity and in exposure to projected thermal warming and hydrologic change.