Lagged climatic effects on carbon fluxes over three grassland ecosystems in China
Lagged climatic effects on carbon fluxes over three grassland ecosystems in China
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DOI：
10.1093/jpe/rtu026
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发表时间：
2015-06
影响因子：
2.7
通讯作者：
Tao Zhang;Mingjie Xu;Y. Xi;Juntao Zhu;Li Tian;Xian-zhou Zhang;Yanfen Wang;Ying-nian Li;
中科院分区：
文献类型：
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作者：
Tao Zhang;Mingjie Xu;Y. Xi;Juntao Zhu;Li Tian;Xian-zhou Zhang;Yanfen Wang;Ying-nian Li;
目的 生态系统响应的可塑性可以缓冲和推迟气候对生态系统碳通量的影响，但这种滞后效应常常被忽视。在本研究中，我们利用内蒙古温带半干旱草原（内蒙古站点，NM）、青海高山灌丛草甸（海北站点，HB）和西藏高山草甸草原（当雄站点，DX）三个典型草原生态系统收集的碳通量数据来检验环境因素对CO2交换的时滞效应。方法采集中国三个典型草原的涡度协方差数据。在将碳通量与气候因素联系起来时，我们使用了每 12 个月内的平均值或累积值，在本研究中我们将其称为“年度”统计数据。为了研究气候因素对碳通量的滞后影响，气候“年度”统计数据保持不变，而碳通量的“年度”统计数据每次向后移动1个月。重要发现土壤湿度和降水分别是驱动高山HB和DX碳通量年变化的主要因素，而NM站点则受到各气候因素的综合影响。时滞效应分析表明，三个研究地点温度对CO2交换的影响存在几个月甚至半年的滞后效应，而水分的影响除NM外大多以即时方式表现出来。总体而言，高山生态系统的滞后气候效应相对较弱。我们的结果表明，生态系统碳通量的变化可能需要几个月甚至一年的时间才能适应当前的气候，因此这种滞后效应可以抵抗更频繁的极端气候，应该成为评估生态系统稳定性时需要考虑的关键组成部分。更好地了解滞后效应可以增进我们对气候变化对生态系统碳通量影响的驱动机制的理解。
Aims The plasticity of ecosystem responses could buffer and postpone the effects of climates on ecosystem carbon fluxes, but this lagged effect is often ignored. In this study, we used carbon flux data collected from three typical grassland ecosystems in China, including a temperate semiarid steppe in Inner Mongolia (Neimeng site, NM), an alpine shrub-meadow in Qinghai (Haibei site, HB) and an alpine meadow steppe in Tibet (Dangxiong site, DX), to examine the time lagged effects of environmental factors on CO2 exchange. Methods Eddy covariance data were collected from three typical Chinese grasslands. In linking carbon fluxes with climatic factors, we used their averages or cumulative values within each 12-month period and we called them 'yearly' statistics in this study. To investigate the lagged effects of the climatic factors on the carbon fluxes, the climatic 'yearly' statistics were kept still and the 'yearly' statistics of the carbon fluxes were shifted backward 1 month at a time. Important Findings Soil moisture and precipitation was the main factor driving the annual variations of carbon fluxes at the alpine HB and DX, respectively, while the NM site was under a synthetic impact of each climatic factor. The time lagged effect analysis showed that temperature had several months, even half a year lag effects on CO2 exchange at the three studied sites, while moisture's effects were mostly exhibited as an immediate manner, except at NM. In general, the lagged climatic effects were relatively weak for the alpine ecosystem. Our results implied that it might be months or even 1 year before the variations of ecosystem carbon fluxes are adjusted to the current climate, so such lag effects could be resistant to more frequent climate extremes and should be a critical component to be considered in evaluating ecosystem stability. An improved knowledge on the lag effects could advance our understanding on the driving mechanisms of climate change effects on ecosystem carbon fluxes.