Spatial variability of photosynthetic production and ecosystem respiration on a hundred-kilometer scale within a Mongolian semiarid grassland
Spatial variability of photosynthetic production and ecosystem respiration on a hundred-kilometer scale within a Mongolian semiarid grassland
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DOI：
10.2480/agrmet.d-13-00026
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发表时间：
2014
影响因子：
1.3
通讯作者：
T. Nakano;M. Shinoda
中科院分区：
文献类型：
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作者：
T. Nakano;M. Shinoda
草地生态系统覆盖了大面积的陆地表面，在全球碳循环中发挥着重要作用。本研究的目的是研究在半干旱草原生态系统的总初级生产力（GPP）和生态系统呼吸（Reco）的空间变异性，并评估控制碳交换的空间格局的环境因素。我们确定了GPP和Reco使用透明和不透明的封闭室，在2009年至2011年的夏天在蒙古中部的9个草原网站。为了消除辐射和温度随时间变化的影响，GPP和Reco被拟合到光和温度响应曲线。在位点之间比较拟合参数（光饱和GPP [Pmax]、表观量子产率[α]、20 °C下的标准化Reco [R20]和Reco的温度灵敏度[Q10]）。GPP和Reco参数在研究中心之间存在显著差异。Pmax和R20的空间格局与植物地上绿色生物量（AGB）和物种数高度相关。Reco的Q10与土壤水分含量呈显著相关。光饱和GPP归一化AGB的量没有显着差异的网站之间，而R20残差的线性生物量模型与土壤含水量和碳/氮比。结果表明，在半干旱草地中，GPP的空间变异受AGB的强烈控制，而Reco的变异主要与AGB有关，其次与土壤水分和土壤养分状况有关。
Grassland ecosystems cover a large area of the land surface and play an important role in the global carbon cycle. The objectives of this study were to examine the spatial variability of gross primary production (GPP) and ecosystem respiration (Reco) within a semiarid grassland ecosystem and to evaluate the environmental factors that control the spatial patterns of carbon exchanges. We determined GPP and Reco using transparent and opaque closed chambers at nine grassland sites in central Mongolia during the summers from 2009 through 2011. To remove effects of temporal changes in radiation and temperature, GPP and Reco were fitted to lightand temperature-response curves. The fitting parameters (light-saturated GPP [Pmax], apparent quantum yield [α], standardized Reco at 20 °C [R20], and the temperature sensitivity [Q10] of Reco) were compared among the sites. The GPP and Reco parameters differed significantly among the sites. Spatial patterns of Pmax and R20 were highly correlated with plant aboveground green biomass (AGB) and number of plant species. The Q10 of Reco was significantly related to soil moisture. The light-saturated GPP normalized to the amount of AGB did not differ significantly among the sites, whereas the R20 residuals of the linear biomass model were correlated with soil water content and carbon/nitrogen ratios. The results suggest that, within this semiarid grassland, spatial variations of GPP are strongly controlled by AGB and that variations in Reco are associated mainly with AGB and secondarily with soil water content and soil nutrient condition.