Yang Xueqin, Wu Jianping, Chen Xiuzhi, Ciais Philippe, Maignan Fabienne, Yuan Wenping, Piao Shilong, Yang Song, Gong Fanxi, Su Yongxian, Dai Yuhang, Liu Liyang, Zhang Haicheng, Bonal Damien, Liu Hui, Chen Guixing, Lu Haibo, Wu Shengbiao, Fan Lei, Gentine Pierre, Wright S Joseph
Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, School of Atmospheric Sciences, Sun Yat-sen University & Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China.
Key Lab of Guangdong for Utilization of Remote Sensing and Geographical Information System, Guangdong Open Laboratory of Geospatial Information Technology and Application, Guangzhou Institute of Geography, Guangdong Academy of Sciences, Guangzhou 510070, China.
Innovation (Camb). 2021 Aug 20;2(4):100154. doi: 10.1016/j.xinn.2021.100154. eCollection 2021 Nov 28.
Relationships among productivity, leaf phenology, and seasonal variation in moisture and light availability are poorly understood for evergreen broadleaved tropical/subtropical forests, which contribute 25% of terrestrial productivity. On the one hand, as moisture availability declines, trees shed leaves to reduce transpiration and the risk of hydraulic failure. On the other hand, increases in light availability promote the replacement of senescent leaves to increase productivity. Here, we provide a comprehensive framework that relates the seasonality of climate, leaf abscission, and leaf productivity across the evergreen broadleaved tropical/subtropical forest biome. The seasonal correlation between rainfall and light availability varies from strongly negative to strongly positive across the tropics and maps onto the seasonal correlation between litterfall mass and productivity for 68 forests. Where rainfall and light covary positively, litterfall and productivity also covary positively and are always greater in the wetter sunnier season. Where rainfall and light covary negatively, litterfall and productivity are always greater in the drier and sunnier season if moisture supplies remain adequate; otherwise productivity is smaller in the drier sunnier season. This framework will improve the representation of tropical/subtropical forests in Earth system models and suggests how phenology and productivity will change as climate change alters the seasonality of cloud cover and rainfall across tropical/subtropical forests.
对于占陆地生产力25%的热带/亚热带常绿阔叶林而言，生产力、叶片物候以及水分和光照可利用性的季节变化之间的关系尚不清楚。一方面，随着水分可利用性下降，树木落叶以减少蒸腾作用和水力故障的风险。另一方面，光照可利用性增加促进衰老叶片的更替以提高生产力。在此，我们提供了一个综合框架，将热带/亚热带常绿阔叶林生物群落中气候的季节性、落叶和叶片生产力联系起来。降雨和光照可利用性之间的季节相关性在热带地区从强负相关到强正相关变化，并与68片森林的凋落物质量和生产力之间的季节相关性相对应。在降雨和光照呈正协变的地方，凋落物和生产力也呈正协变，并且在更湿润、阳光更充足的季节总是更大。在降雨和光照呈负协变的地方，如果水分供应充足，凋落物和生产力在更干燥、阳光更充足的季节总是更大；否则，生产力在更干燥、阳光更充足的季节较小。这个框架将改善地球系统模型中热带/亚热带森林的表征，并表明随着气候变化改变热带/亚热带森林上空云量和降雨的季节性，物候和生产力将如何变化。
