猫头刺群落对土壤养分空间异质性的响应

选择腾格里沙漠边缘内蒙古阿拉善左旗境内的猫头刺群落为研究对象,探讨了猫头刺群落植物属性和土壤属性随尺度变化,空间异质性的变化以及植物属性对土壤属性空间异质性的响应。结果表明,尺度从800 m2增加到1 600 m2,土壤有机质和土壤全氮的空间异质性减小,全磷和有效磷的空间异质性增加,有效氮空间异质性不变,而群落内3种植物密度和叶量的空间异质性基本都趋于增加,说明全磷和有效磷是目前猫头刺群落存在的主要限制因素,尤其是多年生草本植物骆驼蓬。进一步分析表明,这种现象是由于荒漠地区的灌丛“沃岛效应”和植物耗用有效磷以增大吸水力的补偿机制所致。

Response of Oxytropis aciphylla Community to Soil Nutrient Spatial Heterogeneity

In the present study, a sampling plot of 20m×80m in Oxytropis aciphylla community, which located on the eastern boundary of Tengger Desert in the Left Banner of Alashan League in Inner Mongolia, was chose to investigate the quantum feature of plant populations, measure soil total organic matter, total nitrogen, total phosphorus, available nitrogen and available phosphorus within 40 cm depth, and calculate spatial heterogeneity of regional variances of the soil and the vegetation and discuss their responses in accordance with scales. In the plot, there were 100 quadrats of 4m×4m. Results showed that, as scale increase from 800 m2 to 1 600 m2, the spatial heterogeneities of soil organic matter and total nitrogen decreased, the total phosphorus and the available phosphorus increased, and that of available nitrogen remained constant. In the mean time, spatial heterogeneity of the density and the leaf biomass of all three plants increased. These suggested that total phosphorus and available phosphorus are generally the main factors restraining plant distribution in the O. aciphylla community, especially for perennial herbaceous plant Peganum harmala. Further analysis indicated these are caused by island effect of shrubs in the desert and the compensatory mechanism to raise plant suction force using available phosphorus.