Xu Xiaotian, Wu Bo, Bao Fang, Gao Ying, Li Xinle, Cao Yanli, Lu Qi, Gao Junliang, Xin Zhiming, Liu Minghu
Institute of Desertification Studies, Chinese Academy of Forestry, Beijing 100091, China.
Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China.
Plants (Basel). 2023 Mar 3;12(5):1158. doi: 10.3390/plants12051158.
Desert ecosystem CO exchange may play an important role in global carbon cycling. However, it is still not clear how the CO fluxes of shrub-dominated desert ecosystems respond to precipitation changes. We performed a 10-year long-term rain addition experiment in a desert ecosystem in northwestern China. In the growing seasons of 2016 and 2017, with three rain addition treatments (natural precipitation +0%, +50%, and +100% of annual average precipitation), gross ecosystem photosynthesis (GEP), ecosystem respiration (ER), and net ecosystem CO exchange (NEE) were measured. The GEP responded nonlinearly and the ER linearly to rain addition. The NEE presented a nonlinear response along the rain addition gradient, with a saturation threshold by rain addition between +50% and +100%. The growing season mean NEE ranged from -2.25 to -5.38 μmol CO m s, showing net CO uptake effect, with significant enhancement (more negative) under the rain addition treatments. Although natural rainfall fluctuated greatly in the growing seasons of 2016 and 2017, reaching 134.8% and 44.0% of the historical average, the NEE values remained stable. Our findings highlight that growing season CO sequestration in desert ecosystems will increase against the background of increasing precipitation levels. The different responses of GEP and ER of desert ecosystems under changing precipitation regimes should be considered in global change models.
荒漠生态系统的CO交换可能在全球碳循环中发挥重要作用。然而，以灌木为主的荒漠生态系统的CO通量如何响应降水变化仍不清楚。我们在中国西北的一个荒漠生态系统中进行了为期10年的长期增雨实验。在2016年和2017年的生长季，设置了三种增雨处理（自然降水 +0%、+50% 和 +100% 的年平均降水量），测量了生态系统总光合作用（GEP）、生态系统呼吸（ER）和生态系统净CO交换（NEE）。GEP对增雨呈非线性响应，ER呈线性响应。NEE沿增雨梯度呈现非线性响应，增雨在 +50% 至 +100% 之间存在饱和阈值。生长季平均NEE范围为 -2.25至 -5.38 μmol CO m⁻² s⁻¹，呈现净CO吸收效应，增雨处理下显著增强（更负）。尽管2016年和2017年生长季自然降雨波动很大，分别达到历史平均值的134.8% 和44.0%，但NEE值保持稳定。我们的研究结果表明，在降水增加的背景下，荒漠生态系统生长季的CO固存将增加。全球变化模型应考虑降水变化情况下荒漠生态系统GEP和ER的不同响应。
