Bowler Diana, Böhning-Gaese Katrin
Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany.
Institute of Ecology, Evolution & Diversity, Goethe University Frankfurt, Frankfurt am Main, Germany.
PLoS One. 2017 Sep 12;12(9):e0184275. doi: 10.1371/journal.pone.0184275. eCollection 2017.
Climate change indicators are tools to assess, visualize and communicate the impacts of climate change on species and communities. Indicators that can be applied to different taxa are particularly useful because they allow comparative analysis to identify which kinds of species are being more affected. A general prediction, supported by empirical data, is that the abundance of warm-adapted species should increase over time, relative to the cool-adapted ones within communities, under increasing ambient temperatures. The community temperature index (CTI) is a community weighted mean of species' temperature preferences and has been used as an indicator to summarize this temporal shift. The CTI has the advantages of being a simple and generalizable indicator; however, a core problem is that temporal trends in the CTI may not only reflect changes in temperature. This is because species' temperature preferences often covary with other species attributes, and these other attributes may affect species response to other environmental drivers. Here, we propose a novel model-based approach that separates the effects of temperature preference from the effects of other species attributes on species' abundances and subsequently on the CTI. Using long-term population data of breeding birds in Denmark and demersal marine fish in the southeastern North Sea, we find differences in CTI trends with the original approach and our model-based approach, which may affect interpretation of climate change impacts. We suggest that our method can be used to test the robustness of CTI trends to the possible effects of other drivers of change, apart from climate change.
气候变化指标是用于评估、可视化和传达气候变化对物种及群落影响的工具。可应用于不同分类群的指标尤为有用，因为它们能进行比较分析，以确定哪些种类的物种受影响更大。基于实证数据的一个普遍预测是，在环境温度不断升高的情况下，相对于群落中适应凉爽环境的物种，适应温暖环境的物种数量应随时间增加。群落温度指数（CTI）是物种温度偏好的群落加权平均值，已被用作总结这种时间变化的指标。CTI具有简单且可推广的优点；然而，一个核心问题是CTI的时间趋势可能不仅反映温度变化。这是因为物种的温度偏好通常与其他物种属性相关，而这些其他属性可能会影响物种对其他环境驱动因素的反应。在此，我们提出一种基于模型的新方法，该方法将温度偏好的影响与其他物种属性对物种丰度进而对CTI的影响区分开来。利用丹麦繁殖鸟类和北海东南部底层海鱼的长期种群数据，我们发现原始方法和基于模型的方法在CTI趋势上存在差异，这可能会影响对气候变化影响的解读。我们建议，除了气候变化外，我们的方法可用于检验CTI趋势对其他变化驱动因素可能影响的稳健性。
