Widespread seasonal compensation effects of spring warming on northern plant productivity
Widespread seasonal compensation effects of spring warming on northern plant productivity
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DOI：
10.1038/s41586-018-0555-7
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发表时间：
2018-10-04
期刊：
影响因子：
64.8
通讯作者：
Richardson, Andrew D.
中科院分区：
文献类型：
--
作者：
Buermann, Wolfgang;Forkel, Matthias;Richardson, Andrew D.
气候变化正在改变植物的物候周期（1），从而改变生态系统的功能，这反过来又会引起对气候系统的反馈（2）。在北方（北纬30度以北）的生态系统中，温暖的春天通常会导致生长季节的提前开始（3，4），并在季节早期增加生态系统的生产力（5）。原位（6）和区域（7-9）研究也提供了证据，证明春季温暖对随后的夏季和秋季植物生产力的滞后影响。然而，我们目前对这些滞后效应的了解，包括其方向（有利或不利）和地理分布，仍然非常有限。在这里，我们分析了1982年至2011年期间的卫星，实地和建模数据，并表明在北方生态系统中，春季温暖的生产力响应普遍存在，且存在对比滞后。根据观测数据，我们发现，在约4 100万平方公里的研究总面积中，约有15%显示出不利的滞后效应，约有5%显示出有利的滞后效应。相比之下，目前的陆地碳循环模型预测的不利滞后效应的面积比例要低得多（从1%到14%不等），有利滞后效应的面积比例要高得多（从9%到54%不等）。我们发现，海拔和季节性降水模式在很大程度上决定了地理格局和方向的滞后效应。因此，在当前的模型中，对季节性水分胁迫对季节性植被生长的影响考虑不足，可能能够解释我们在观测约束估计和模型约束估计与春季变暖相关的滞后效应之间发现的差异。总的来说，我们的研究结果表明，对于许多北方生态系统来说，温暖的春天对生长季节生态系统生产力的好处被季节性缺水的积累有效地补偿了，尽管北方生态系统被认为在很大程度上受到温度和辐射的限制（10）。
Climate change is shifting the phenological cycles of plants(1), thereby altering the functioning of ecosystems, which in turn induces feedbacks to the climate system(2). In northern (north of 30 degrees N) ecosystems, warmer springs lead generally to an earlier onset of the growing season(3,4) and increased ecosystem productivity early in the season(5). In situ(6) and regional(7-9) studies also provide evidence for lagged effects of spring warmth on plant productivity during the subsequent summer and autumn. However, our current understanding of these lagged effects, including their direction (beneficial or adverse) and geographic distribution, is still very limited. Here we analyse satellite, field-based and modelled data for the period 1982-2011 and show that there are widespread and contrasting lagged productivity responses to spring warmth across northern ecosystems. On the basis of the observational data, we find that roughly 15 per cent of the total study area of about 41 million square kilometres exhibits adverse lagged effects and that roughly 5 per cent of the total study area exhibits beneficial lagged effects. By contrast, current-generation terrestrial carbon-cycle models predict much lower areal fractions of adverse lagged effects (ranging from 1 to 14 per cent) and much higher areal fractions of beneficial lagged effects (ranging from 9 to 54 per cent). We find that elevation and seasonal precipitation patterns largely dictate the geographic pattern and direction of the lagged effects. Inadequate consideration in current models of the effects of the seasonal build-up of water stress on seasonal vegetation growth may therefore be able to explain the differences that we found between our observation-constrained estimates and the model-constrained estimates of lagged effects associated with spring warming. Overall, our results suggest that for many northern ecosystems the benefits of warmer springs on growing-season ecosystem productivity are effectively compensated for by the accumulation of seasonal water deficits, despite the fact that northern ecosystems are thought to be largely temperature-and radiation-limited(10).