荒漠草原不同沙化草地柠条灌丛表层土壤固碳研究

Carbon sequestration of Caragana korshinskii shrubs surface soil in different desertified grassland of desert steppe

为系统认识荒漠草原柠条灌丛灌草植被长期影响下土壤有机碳演变规律,以天然草地(T1)、灰钙土草地(T2)、结皮草地(T3)、固定沙丘草地(T4)、半固定沙丘草地(T5)、流动沙丘草地(T6)6个不同沙化梯度草地为研究对象,分析大中小3个冠幅尺度灌丛内外土壤的固碳效应。结果表明:(1)各沙化梯度草地柠条(灌丛内外)比较:土壤总有机碳(TOC)含量在流动沙丘草地最低(P<0.01),在天然草地最高(P<0.01)。灌丛内活性有机碳(AOC)含量在结皮草地最高(P<0.01),灌丛内结皮的存在对AOC的固定起到了重要作用。(2)各沙化梯度草地大中小柠条灌丛比较:灌丛内部,总体上中等冠幅灌丛TOC、AOC、惰性有机碳(NOC)含量最高(P<0.01),柠条灌丛发育中期是柠条草地土壤有机碳积累的一个拐点,也是灌丛内部"肥岛效应"最集中的体现;灌丛外部、结皮草地和流动沙丘草地的小灌丛TOC、NOC含量极显著高于大灌丛,活性有机碳的变化规律与之相反。研究认为:随着柠条灌丛的发育,土壤固碳先增加后降低,在中等冠幅尺度下固碳效益最显著。柠条灌丛土壤固碳效应可能是灌木和地表结皮的综合作用。

To understand the soil organic carbon evolution under the long-term effects of in desert steppe,taking 6 kinds of grassland with different desertification gradient： natural grassland（T1）, sierozem grassland（T2）,crusts grassland（T3）,fixed sand dune grassland（ T4）,semi-fixed sand dune grassland（ T5）,mobile sand dune grassland（ T6） as research objects,to analyze the soil carbon sequestration in internal and external of shrubs with large,medium and small crown. The results showed that ：（1）In internal and external of C. korshinskii shrubs,the lowest TOC contents was in the mobile sand dune grassland（ P〈0.01）,the highest was in the natural grassland（ P〈0.01）. The highest AOC content was in the crusts grassland with internal of shrubs（ P〈0.01）,the existence of internal of shrubs played an important role in AOC sequestration.（ 2）The large,medium and small crown of C. korshinskii were compared,the results showed that in the internal of shrubs,on the whole,the highest TOC,AOC and NOC contents were in the medium crown of C. korshinskii（P〈0.01）,medium crown was a turning point of C. korshinskii soil organic carbon accumulation,it was the most concentrated expression of＂ fertile island effect＂ with internal of shrubs. In the external of shrubs,TOC and NOC of small crown in the crusts grassland and mobile sand dune grassland were higher than those in the large crown significantly（ P〈0.01）,the variation of AOC was opposite. It suggested that soil carbon sequestration showed a decreasing trend after a increase,the best soil carbon sequestration was in the medium crown of C. korshinskii. C. korshinskii soil carbon sequestration effects were the integrated action of C. korshinskii and crusts grassland.