Department of Biology, MSC03-2020, University of New Mexico, Albuquerque, New Mexico, 87131, USA.
Ecology. 2018 Mar;99(3):576-582. doi: 10.1002/ecy.2136.
Understanding controls on net primary production (NPP) has been a long-standing goal in ecology. Climate is a well-known control on NPP, although the temporal differences among years within a site are often weaker than the spatial pattern of differences across sites. Climate sensitivity functions describe the relationship between an ecological response (e.g., NPP) and both the mean and variance of its climate driver (e.g., aridity index), providing a novel framework for understanding how climate trends in both mean and variance vary with NPP over time. Nonlinearities in these functions predict whether an increase in climate variance will have a positive effect (convex nonlinearity) or negative effect (concave nonlinearity) on NPP. The influence of climate variance may be particularly intense at ecosystem transition zones, if species reach physiological thresholds that create nonlinearities at these ecotones. Long-term data collected at the confluence of three dryland ecosystems in central New Mexico revealed that each ecosystem exhibited a unique climate sensitivity function that was consistent with long-term vegetation change occurring at their ecotones. Our analysis suggests that rising temperatures in drylands could alter the nonlinearities that determine the relative costs and benefits of variance in precipitation for primary production.
了解净初级生产力（NPP）的控制因素一直是生态学中的一个长期目标。气候是对 NPP 的一个众所周知的控制因素，尽管一个地点内各年之间的时间差异通常比各地点之间的空间差异模式弱。气候敏感函数描述了生态响应（例如 NPP）与其气候驱动因素（例如干旱指数）的平均值和方差之间的关系，为理解随着时间的推移，NPP 与气候平均值和方差的趋势如何变化提供了一个新的框架。这些函数中的非线性预测了气候方差的增加对 NPP 是会产生积极影响（凸非线性）还是消极影响（凹非线性）。如果物种达到了在这些生态过渡带产生非线性的生理阈值，那么这些函数中的非线性可能会在生态系统过渡带产生特别强烈的影响。在新墨西哥州中部三个旱地生态系统的交汇处收集的长期数据表明，每个生态系统都表现出独特的气候敏感函数，与它们生态过渡带的长期植被变化一致。我们的分析表明，干旱地区的气温升高可能会改变决定降水方差对初级生产力的相对成本和收益的非线性。
