Soil carbon and nitrogen stores and storage potential as affected by land-use in an agro-pastoral ecotone of northern China
Soil carbon and nitrogen stores and storage potential as affected by land-use in an agro-pastoral ecotone of northern China
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DOI：
10.1007/s10533-006-9058-y
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发表时间：
2007-01
期刊：
影响因子：
4
通讯作者：
Zhiyong Zhou;O. Sun;Jianhui Huang;Linghao Li;Ping Liu;Xingguo Han
中科院分区：
文献类型：
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作者：
Zhiyong Zhou;O. Sun;Jianhui Huang;Linghao Li;Ping Liu;Xingguo Han
平衡碳储存是碳库输入和流出之间平衡的结果。土地利用的变化可能改变这种平衡，除了全球气候变化的影响外，还导致不同土地利用类型下的碳储存不同。在内蒙古农牧交错带，研究了放牧、禁牧、刈割、玉米种植园、休闲和苜蓿草地6种不同土地利用方式下的生产力和地下碳氮储量，以及对草地凋落物和细根的影响。结果表明：6种土地利用方式的地上净初级生产力（ANPP）差异较大，其中CP的ANPP显著高于其他土地利用方式; FG的土壤有机碳（SOC）和氮储量（SON）显著低于其他土地利用方式，而FG和CP的枯落物积累很少。土壤表层20 cm处的根系碳、氮含量约占80%，50 cm以下的根系含量很少。约60%的SOC和SON储存在表层30 cm。土地利用变化改变了有机物的输入，从而影响SOC和SON存储相应的MW和GE网站有59%和56%以上的SOC和61%以上的SON比FG。我们的估计表明，恢复严重退化和过度放牧的草地可能会增加SOC和SON存储超过55%;从原生草到苜蓿的转换可能会使地上生物量增加一倍，并进一步增加SOC和SON存储超过20%。研究表明，在全球气候变化背景下，通过土地利用变化和管理改善，中国北方农牧交错带具有显著的碳氮储量潜力。
Equilibrium carbon stock is the result of a balance between inputs and outflows to the pool. Changes in land-use are likely to alter such balance, resulting in different carbon stores under different land-use types in addition to the impacts of global climate change. In an agro-pastoral ecotone of Inner Mongolia, northern China, we investigated productivity and belowground carbon and nitrogen stores under six different types of land-uses, namely free grazing (FG), grazing exclusion (GE), mowing (MW), corn plantation (CP), fallow (FL), and alfalfa pasture (AP), and their impacts on litter and fine roots in semiarid grassland ecosystems. We found that there were great variations in aboveground net primary production (ANPP) across the six land-use types, with CP having markedly high ANPP; the FG had significantly reduced soil organic carbon (SOC) and nitrogen stores (SON) to 100 cm depth compared with all other types of land uses, while very little litter accumulation was found on sites of the FG and CP. The top 20 cm of soils accounted for about 80% of the root carbon and nitrogen, with very little roots being found below 50 cm. About 60% of SOC and SON were stored in the top 30 cm layer. Land-use change altered the inputs of organic matters, thus affecting SOC and SON stores accordingly; the MW and GE sites had 59 and 56% more SOC and 61% more SON than the FG. Our estimation suggested that restoring severely degraded and overgrazed grasslands could potentially increase SOC and SON stores by more than 55%; conversion from the native grasses to alfalfa could potentially double the aboveground biomass production, and further increase SOC and SON stores by more than 20%. Our study demonstrated significant carbon and nitrogen storage potential of the agro-pastoral ecotone of northern China through land-use changes and improved management in the context of mitigating global climate change.