Zhang Simin, Liu Tingxi, Duan Limin, Hao Lina, Tong Xin, Jia Tianyu, Li Xia, Lun Shuo
College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China.
College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; Inner Mongolia Autonomous Region Key Laboratory of Water Resources Protection and Utilization, Hohhot 010018, China; Inner Mongolia section of the Yellow River Basin Water Resources and Water Environment Comprehensive Management Autonomous Region Collaborative Innovation Center, Hohhot 010018, China.
Sci Total Environ. 2024 Mar 25;918:170517. doi: 10.1016/j.scitotenv.2024.170517. Epub 2024 Jan 29.
Sandy regions constitute pivotal components of terrestrial ecosystems, exerting significant influences on global ecological equilibrium and security. This study meticulously explored water and carbon fluxes dynamics within a dune ecosystem in the Horqin Sandy Land throughout the growing seasons from 2013 to 2022 by employing an advanced eddy covariance system. The dynamic characteristics of these fluxes and their underlying driving forces were extensively analyzed, with a particular focus on the impact of precipitation. The main results are as follows: (1) During the growing seasons of 2015 and 2016, the dune ecosystem acted as a modest carbon source, while in 2013, 2014, and 2017- 2022, it transformed into a net carbon sink. Notably, the annual mean values of water use efficiency (WUE) and evapotranspiration (ET) were 5.16 gC·kgHO and 255.4 mm, respectively. (2) The intensity, frequency, and temporal distribution of precipitation were found to significantly influence the carbon and water fluxes dynamics. Isolated minor precipitation events did not trigger substantial fluctuations, but substantial and prolonged precipitation events spanning multiple days or consecutive minor precipitation events resulted in notable assimilation delays. (3) Air temperature, soil temperature, and fractional vegetation cover (FVC) were found to be key factors influencing the carbon and water fluxes. Specifically, FVC exhibited a negative logarithmic correlation with net ecosystem CO exchange (NEE) and a power function relationship with WUE. (4) The interaction between carbon and water fluxes is exhibited by exponential increases in ecosystem respiration (Reco) and gross primary productivity (GPP) with WUE, while NEE displayed an exponential decrease in relation to WUE. These findings are of high significance in predicting the potential ramifications of climate change on the intricate carbon and water cycles, and enhance our understanding of ecosystem dynamics in sandy environments.
沙地是陆地生态系统的关键组成部分，对全球生态平衡和安全具有重大影响。本研究利用先进的涡度协方差系统，对2013年至2022年生长季期间科尔沁沙地沙丘生态系统内的水碳通量动态进行了细致探究。深入分析了这些通量的动态特征及其潜在驱动力，尤其关注降水的影响。主要结果如下：（1）在2015年和2016年生长季，沙丘生态系统为适度碳源，而在2013年、2014年以及2017年至2022年，它转变为净碳汇。值得注意的是，水分利用效率（WUE）和蒸散量（ET）的年平均值分别为5.16 gC·kgH₂O和255.4 mm。（2）发现降水的强度、频率和时间分布对碳通量和水通量动态有显著影响。孤立的小降水事件不会引发大幅波动，但持续多日的大量降水事件或连续的小降水事件会导致明显的同化延迟。（3）气温、土壤温度和植被覆盖度（FVC）是影响碳通量和水通量的关键因素。具体而言，FVC与生态系统净CO₂交换量（NEE）呈负对数相关，与WUE呈幂函数关系。（4）碳通量和水通量之间的相互作用表现为生态系统呼吸（Reco）和总初级生产力（GPP）随WUE呈指数增加，而NEE与WUE呈指数下降关系。这些发现对于预测气候变化对复杂的碳循环和水循环的潜在影响具有重要意义，并增进了我们对沙地环境中生态系统动态的理解。
