Precipitation Pattern Determines the Inter-annual Variation of Herbaceous Layer and Carbon Fluxes in a Phreatophyte-Dominated Desert Ecosystem
Precipitation Pattern Determines the Inter-annual Variation of Herbaceous Layer and Carbon Fluxes in a Phreatophyte-Dominated Desert Ecosystem
复制标题
降水格局决定了以苔藓植物为主的荒漠生态系统草本层和碳通量的年际变化
DOI：
10.1007/s10021-015-9954-x
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发表时间：
2016-06-01
期刊：
影响因子：
3.7
通讯作者：
Ma, Jie
中科院分区：
文献类型：
--
作者：
Liu, Ran;Cieraad, Ellen;Ma, Jie
以灌木物种为主的干旱和半干旱生态系统是全球碳循环的一个重要组成部分，但在气候变化对碳通量影响的研究中却基本上没有得到充分的体现。本研究综合了长期涡度相关测量和实验的数据，以评估由降水模式驱动的生态系统组成的变化如何影响以深根灌木（潜水植物，依赖于地下水作为主要水源）为主的盐生植物沙漠群落中碳通量及其组分的年际变化。研究结果表明，该群落的碳平衡对降水量的变化有很强的响应。生长季前降水和生长季降水频率对生态系统碳通量的年际变化均有显著影响。生长季前的大量降水（11月至4月，主要是雪）增加了年度净生态系统碳交换，促进了浅根一年生植物的生长和碳同化，利用春季和夏季降水来提高群落生产力。充足的生长季前降水有利于浅根一年生植物的萌发和生长。当高频率的生长季降水后，群落生产力提高到草原或森林生态系统的水平。长期的观测和实验结果证实，降水模式和草本成分是该生态系统碳动态的主要驱动力。这项研究说明了气候和生态系统组成的年际变化对干旱和半干旱生态系统碳通量的重要性。它还强调了未来几十年降水频率和季节模式的变化对区域和全球碳循环的重要影响。
Arid and semi-arid ecosystems dominated by shrubby species are an important component in the global carbon cycle but are largely under-represented in studies of the effect of climate change on carbon flux. This study synthesizes data from long-term eddy covariance measurements and experiments to assess how changes in ecosystem composition, driven by precipitation patterns, affect inter-annual variability of carbon flux and their components in a halophyte desert community dominated by deep-rooted shrubs (phreatophytes, which depend on groundwater as their primary water source). Our results demonstrated that the carbon balance of this community responded strongly to precipitation variations. Both pre-growing season precipitation and growing season precipitation frequency significantly affected inter-annual variations in ecosystem carbon flux. Heavy pre-growing season precipitation (November-April, mostly as snow) increased annual net ecosystem carbon exchange, by facilitating the growth and carbon assimilation of shallow-rooted annual plants, which used spring and summer precipitation to increase community productivity. Sufficient pre-growing season precipitation led to more germination and growth of shallow-rooted annual plants. When followed by high-frequency growing season precipitation, community productivity of this desert ecosystem was lifted to the level of grassland or forest ecosystems. The long-term observations and experimental results confirmed that precipitation patterns and the herbaceous component were dominant drivers of the carbon dynamics in this phreatophyte-dominated desert ecosystem. This study illustrates the importance of inter-annual variations in climate and ecosystem composition for the carbon flux in arid and semi-arid ecosystems. It also highlights the important effect of changing frequency and seasonal pattern of precipitation on the regional and global carbon cycle in the coming decades.