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有读书笔记Using the CENTURY model to assess the impact of land reclamation and management practices in oasis agriculture on the dynamics of soil organic carbon in the arid region of North-western China

唐唐 添加于 2011-6-2 00:13 | 4492 次阅读 | 0 个评论

  •  作 者

    Xu W, Chen X, Luo G, Lin Q

  •  摘 要

    Large-scale reclamation of arid land in North-western China over the past 50 years has converted the natural desert landscape into anthropogenic oasis, particularly in the lower part of watersheds. Drastic human activities may have caused the change of soil organic carbon (SOC) in anthropogenic oasis. This study employs the CENTURY model (Version 4.0) to investigate the effects of land reclamation and management practices in oasis agriculture on the dynamic of SOC at the lower part of Sangong river watershed, a typical anthropogenic oasis reclaimed at 50 years ago. Based on field investigation, history of crop rotations, and past farm practices in study area, land management practices were divided into five categories, corresponding five periods, 0–1958, 1959–1984, 1985–1992, 1993–1998 and 1999–2008. The model successfully simulated the SOC dynamics of the top layer soil (0–20 cm) in the different periods. The state of equilibrium of total SOC and the active, slow, and passive carbon pools were built by CENTURY model in 0–1959. Over the 50 years’ cultivation (1959–2008), the mean change in total SOC exhibited complex ways. SOC increased rapidly in the first 2 years (1959–1960) after shrubland reclamation, and declined slowly during the period 1961–1984 and then decreased rapidly from 1985 to 1992. Between 1993 and 1998, it remained relatively stable, and climbed rapidly again during 1999–2008. The trend in total SOC showed “N” shape, i.e., increase, decrease, then increase. Finally, total SOC is greater (8.2%) in 2008 than the original level of SOC under the natural desert shrub. The improvements of land management practices such as ploughing being replaced with no tillage, straw being crushed before returning it to soil, and reasonable application of fertilizers, played a key role in the change in total SOC. Especially, soil carbon sequestration was obviously increased since protective management practices were implemented in 1993, such as no tillage, straw returning to soil, and the balanced fertilization technique. The results were different from the conclusions that loss of soil organic carbon would happen due to reclamation and continuous farming in tropical forests, semiarid grasslands of northern China and Nigerian semiarid Savannah.

  •  详细资料

    • 文献种类: Journal Article
    • 期刊名称: Ecological Complexity
    • 期刊缩写: Ecological Complexity
    • 期卷页: 2011年  第8卷 第1期 30-37页
    • ISBN: 1476945X

  • 学科领域 农业科学 » 林学

  •  所属群组

    农业科学  

  • 相关链接 DOI URL 

  •  唐唐 的文献笔记  订阅

    表层土壤有机碳总体呈碳汇趋势
    土壤有机碳（SOC）库是陆地生物圈中最大的碳库，约占陆地生态系统总碳储量的三分之二， 其中农田土壤有机碳库占全球陆地碳库的8%—10%。然而，由人类活动引起的土地利用/覆盖变化已成为影响土壤碳库动态的最直接原因，其中最严重的干扰就 是将自然植被转变为耕地。中国西北干旱区具有独特的山盆相间的地貌格局，形成了典型的以“山地－绿洲－荒漠”为主体的流域生态系统，其结构完全不同于世界 其它干旱区，如非洲Savanna稀树草原地区、中东干旱沙漠区域、澳洲中西部干旱区及北美干旱区等。中国西北干旱区流域生态系统一直受到人类活动的强烈 影响，半个世纪前人类大规模的水土开发使得流域下部的荒漠覆被土地转变为人工绿洲，以天山北坡为例，近50年耕地面积增幅约150%，其后在不同农业管理 模式的影响下，土壤碳库发生了显著变化。
     
    中国科学院新疆生态与地理研究所陈曦研究团队，在国家重点基础研究发展计划（973计划） （2009CB825105）的支持下，以干旱区典型的三工河流域下部的人工绿洲为例，基于CENTURY模型，研究了人工绿洲开发前后及农业管理模式变 化对表层土壤有机碳库（0-20cm）的影响。CENTURY模型模拟结果表明：（1）研究区荒漠灌木林地开垦为人工绿洲后，在最初的两年土壤总有机碳 （TOC）快速增加，随后呈逐渐下降的趋势；（2）研究区人工绿洲在被开发后50年的连续耕作下，平均土壤TOC呈先增后减再增的“N”型变化趋势，但最 终土壤TOC超过了原始自然状态下的TOC，而且2008年土壤TOC比原始荒漠状态增加7.74%，说明研究区表层土壤有机碳总体呈“碳汇”趋势。
     
    尤其在研究区实施了免耕、秸秆粉碎还田、科学测土配方施肥等保护性耕作措施后，土壤固碳效应明显，这完全不同于热带森林、中国北部温带半干旱草原及非洲Savanna半干旱稀树草原开垦为耕地后土壤有机碳大量损失的结论。
     
    相关研究成果发表于《生态复杂性》（Ecological Complexity ）(Volume 8, issue 1, 2011)。（来源：中国科学院新疆生态与地理研究所）
     
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