Teng Dexiong, Gong Xuewei, He Xuemin, Wang Jingzhe, Lv Guanghui, Wang Jinlong, Yang Xiaodong
CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
College of Ecology and Environment, Xinjiang University, Urumqi, China.
Front Plant Sci. 2024 Apr 18;15:1332192. doi: 10.3389/fpls.2024.1332192. eCollection 2024.
The desert riparian forests are susceptible to meteorological changes and contribute significantly to the net ecosystem productivity (NEP) variations of arid ecosystems. However, the responsive patterns of their NEP variations to the meteorological variabilities remain inadequately comprehended. To address this gap, we utilized seven years of eddy covariance flux measurements in a representative desert riparian forest to investigate the NEP variations and its response to changing meteorological factors across diverse temporal scales. The results revealed significant periodic variations in half-hourly NEP, with dominant cycles spanning from five hours to one year, with a principal oscillation period of one day. Key meteorological factors including global solar radiation (Rg), relative humidity (RH), air temperature (Ta), soil temperature (Ts), and vapor pressure deficit (VPD) exhibited synchronization with NEP on daily scales. This synchronization, coupled with the observed one-day periodic NEP variations, provides robust evidence supporting the existence of a circadian rhythm in the ecosystem carbon exchange of desert riparian forest regulated by meteorological conditions. Seasonal patterns were significant in the impact of Rg phase, Ta diurnal amplitude, and VPD diurnal amplitude on NEP diurnal amplitude and phase. The NEP diurnal amplitude significantly, directly, and positively affected daily NEP in both the dormant and growing seasons, whereas its phase yielded significant negative effects (< 0.05). The averages, amplitudes, and phases of diurnal meteorological conditions controlled the daily NEP by regulating NEP diurnal amplitude and phase. These findings provide evidence that the variability in circadian rhythms, caused by the increase in diurnal Ta and VPD, significantly impact the daily NEP at an ecosystem scale. This study enriches our comprehension of the meteorological mechanisms governing diurnal and seasonal carbon uptake dynamics within desert riparian forests, providing fresh insights into the direct and indirect roles of climate change in shaping patterns of ecosystem carbon exchange.
沙漠河岸森林易受气象变化影响，对干旱生态系统的净生态系统生产力（NEP）变化有显著贡献。然而，其NEP变化对气象变率的响应模式仍未得到充分理解。为填补这一空白，我们利用在一片具有代表性的沙漠河岸森林中进行的七年涡度协方差通量测量，来研究NEP变化及其在不同时间尺度上对不断变化的气象因素的响应。结果显示，半小时NEP存在显著的周期性变化，主导周期从五小时到一年不等，主要振荡周期为一天。包括全球太阳辐射（Rg）、相对湿度（RH）、气温（Ta）、土壤温度（Ts）和水汽压差（VPD）在内的关键气象因素在日尺度上与NEP表现出同步性。这种同步性，再加上观测到的NEP一日周期性变化，有力地证明了在气象条件调节下，沙漠河岸森林生态系统碳交换中存在昼夜节律。Rg相位、Ta日振幅和VPD日振幅对NEP日振幅和相位的影响具有显著的季节模式。NEP日振幅在休眠季节和生长季节均对每日NEP产生显著、直接且正向的影响，而其相位则产生显著的负向影响（<0.05）。昼夜气象条件的平均值、振幅和相位通过调节NEP日振幅和相位来控制每日NEP。这些发现表明，由昼夜Ta和VPD增加引起的昼夜节律变化，在生态系统尺度上对每日NEP有显著影响。本研究丰富了我们对沙漠河岸森林中昼夜和季节碳吸收动态的气象机制的理解，为气候变化在塑造生态系统碳交换模式中的直接和间接作用提供了新的见解。
