内蒙古退化草原中与小叶锦鸡儿相关的小尺度土壤碳、氮资源异质性动态

Dynamics of the small-scale heterogeneity of the soil carbon and nitrogen resources associated with Caragana microphylla in Inner Mongolia degraded steppe

小叶锦鸡儿在内蒙古典型草原中有着广泛分布,从而对小空间尺度土壤资源异质性产生强烈影响。退化草原中小叶锦儿能够通过克隆生长形成灌丛斑块,不同大小斑块对应于其发育的不同阶段。因此,通过对与不同大小灌丛斑块相关的土壤机碳(SOC)、全氮(STN)空间分布状况的分析,能够推断内蒙古退化草原中、与小叶锦鸡儿相关的小尺度SOC与STN异质性态。结果表明:在内蒙古退化草原中,就0～5cm,5～10cm,10～20cm3个土壤层次,小叶锦鸡儿均导致了与灌丛斑块相关小尺上SOC与STN分布的空间异质性,且随着灌丛斑块的发育,这种异质性均不断增强,其中土壤表层0～5cm碳氮资源异质性的强最为强烈,表现在灌丛斑块内部相对于外部(或边缘)对SOC与STN富集程度均显著增加。这表明内蒙古退化草原中,随灌丛斑块自身的扩展,与小叶锦鸡儿相关小尺度上土壤碳氮资源空间异质性趋于增强。

Caragana microphylla has been widespread in Inner Mongolia steppe, and therefore it can strongly influence the smallscale heterogenity of soil resources. Caragena microphylla could form a patch through the clonal growth in the degraded steppe. A patch with different size could be viewed as its distinct development stage. Therefore, we could infer the dynamics of small-scale heterogeneity of the SOC and STN associated with Caragena microphylla in Inner Mongolia degraded steppe, by analyzing the distribution of SOC and STN associated with a series of shrub patches. Results showed that, for 0 - 5cm, 5 - 10cm, and 10 - 20cm soil depths, Caragana microphylla could induce the spatial heterogeneity of SOC and STN at small-scale associated with shrub patches, and this heterogeneity tended to increase as a shrub patch developed, especially it rose fastest for the surficial 0 -5cm soil depth, which is showed that the increment of the SOC and STN in the 0 -5cm soil depths, for the inside relative to the outside （or the edge） of shrub patches, was increased significantly with a shrub patch expanding. It suggested that the small-scale heterogeneity of the SOC and STN associated with Caragana microphylla has a self-reinforcing process as a shrub patch expanded, in Inner Mongolia degraded steppe.