Wang Yawen, Xu Wenfang, Yuan Wenping, Chen Xiuzhi, Zhang Bingwei, Fan Lei, He Bin, Hu Zhongmin, Liu Shuguang, Liu Wei, Piao Shilong
Physical Oceanography Laboratory, College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China.
School of Atmospheric Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Zhuhai 519082, China.
Innovation (Camb). 2021 Sep 23;2(4):100163. doi: 10.1016/j.xinn.2021.100163. eCollection 2021 Nov 28.
It has been long established that the terrestrial vegetation in spring has stronger photosynthetic capability than in autumn. However, this study challenges this consensus by comparing photosynthetic capability of terrestrial vegetation between the spring and autumn seasons based on measurements of 100 eddy covariance towers over global extratropical ecosystems. At the majority of these sites, photosynthetic capability, indicated by light use efficiency (LUE) and apparent quantum efficiency, is significantly higher in autumn than in spring, due to lower atmosphere vapor pressure deficit (VPD) at the same air temperature. Seasonal VPD differences also substantially explain the interannual variability of the differences in photosynthetic capability between spring and autumn. We further reveal that VPD in autumn is significantly lower than in spring over 74.14% of extratropical areas, based on a global climate dataset. In contrast, LUE derived from a data-driven vegetation production dataset is significantly higher in autumn in over 61.02% of extratropical vegetated areas. Six Earth system models consistently projected continuous larger VPD values in spring compared with autumn, which implies that the impacts on vegetation growth will long exist and should be adequately considered when assessing the seasonal responses of terrestrial ecosystems to future climate conditions.
长期以来，人们一直认为春季的陆地植被比秋季具有更强的光合能力。然而，本研究通过基于全球温带生态系统中100座涡度相关塔的测量数据，比较春季和秋季陆地植被的光合能力，对这一共识提出了挑战。在这些站点中的大多数，以光能利用效率（LUE）和表观量子效率表示的光合能力，在秋季显著高于春季，这是因为在相同气温下，大气水汽压差（VPD）较低。季节性VPD差异也很大程度上解释了春季和秋季光合能力差异的年际变化。基于全球气候数据集，我们进一步揭示，在74.14%以上的温带地区，秋季的VPD显著低于春季。相比之下，在61.02%以上的温带植被区，从数据驱动的植被生产数据集中得出的LUE在秋季显著更高。六个地球系统模型一致预测，与秋季相比，春季的VPD值将持续更大，这意味着对植被生长的影响将长期存在，在评估陆地生态系统对未来气候条件的季节性响应时应予以充分考虑。
