Padfield Daniel, Lowe Chris, Buckling Angus, Ffrench-Constant Richard, Jennings Simon, Shelley Felicity, Ólafsson Jón S, Yvon-Durocher Gabriel
Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, TR10 9EZ, UK.
Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9FE, UK.
Ecol Lett. 2017 Oct;20(10):1250-1260. doi: 10.1111/ele.12820. Epub 2017 Aug 29.
Gross primary production (GPP) is the largest flux in the carbon cycle, yet its response to global warming is highly uncertain. The temperature dependence of GPP is directly linked to photosynthetic physiology, but the response of GPP to warming over longer timescales could also be shaped by ecological and evolutionary processes that drive variation in community structure and functional trait distributions. Here, we show that selection on photosynthetic traits within and across taxa dampens the effects of temperature on GPP across a catchment of geothermally heated streams. Autotrophs from cold streams had higher photosynthetic rates and after accounting for differences in biomass among sites, biomass-specific GPP was independent of temperature in spite of a 20 °C thermal gradient. Our results suggest that temperature compensation of photosynthetic rates constrains the long-term temperature dependence of GPP, and highlights the importance of considering physiological, ecological and evolutionary mechanisms when predicting how ecosystem-level processes respond to warming.
总初级生产力（GPP）是碳循环中最大的通量，但其对全球变暖的响应高度不确定。GPP对温度的依赖性直接与光合作用生理相关，但在更长的时间尺度上，GPP对变暖的响应也可能受到驱动群落结构和功能性状分布变化的生态和进化过程的影响。在这里，我们表明，在一个地热加热溪流集水区内，对不同分类群内部和之间光合性状的选择减弱了温度对GPP的影响。来自寒冷溪流的自养生物具有较高的光合速率，并且在考虑了不同地点生物量的差异之后，尽管存在20°C的热梯度，但特定生物量的GPP与温度无关。我们的结果表明，光合速率的温度补偿限制了GPP对温度的长期依赖性，并突出了在预测生态系统水平过程如何响应变暖时考虑生理、生态和进化机制的重要性。
