古尔班通古特沙漠土壤化学性质空间异质性的尺度特征

从根际(10-3m~10-2m)、个体(10-1m~100m)、种群(100m~101m)、地貌(101m~102m)和区域(103m~104m)五个作用因子所在的尺度对古尔班通古特沙漠土壤的pH、电导率、有机质、全氮、速效氮、全磷和速效磷的空间异质性进行了研究,结果表明,土壤pH在各尺度异质性的大小顺序为:个体>种群>地貌>区域>根际,说明引起土壤pH变化的主要因子是植物个体和种群,而地貌状况、气候及水文对于土壤pH的影响不大,根际对土壤pH的影响最小。土壤电导率在各尺度异质性的大小顺序为:个体>区域>种群>地貌>根际,说明植物个体对于改变土壤盐分含量起主导作用,地貌状况和根际对土壤盐分状况的影响很小。土壤有机质、全氮、速效氮和速效磷的空间异质性均在个体尺度上最大,地貌尺度上次之,而种群尺度上最小,说明植物个体对于土壤养分的空间异质性起主导作用,地貌对这些养分的异质性作用也是不容忽视的,而植物种群对土壤养分的异质性最小。土壤全磷的异质性则在地貌尺度最大,个体尺度次之,根际尺度最小,说明地貌特征是影响土壤全磷含量的主要因子,其次是植物个体,而根际对于土壤全磷的影响很小。

Scale characteristics of spatial heterogeneity of soil chemical properties in Gurbantunggut Desert

The study was designed to study spatial variation of soil pH, electrical conductivity, soil organic carbon, total nitrogen, available nitrogen, total phosphorus and available phosphorus, and scale characteristics of spatial heterogeneity of the soil chemical properties at various scales, such as rhizosphere, individual, population, topography and region, separately in the Gurbantunggut Desert, with the purpose of finding out at which scale the heterogeneity was the greatest and its dominating factor. Results show that soil pH demonstrating an order of individual > population > topography > region > rhizosphere, which indicated that the variation of soil pH in the desert ecosystem was dominated by the biotic progress of plant individual and population. The effects of topography, climate and hydraulics were very limited, and the effect of rhizosphere was the least. In terms of electrical conductivity, the scales followed the order of individual > region > population > topography > rhizosphere, which demonstrated that an individual of shrub played a dominating role in variation of soil salt around the taproot. For soil organic carbon, total nitrogen, available nitrogen and available phosphorus, the highest heterogeneity also existed at the individual scale, which was followed by the topography scale, and the least did at the population scale, which suggested shrub individuals were the factor dominating soil nutrients, topography was the next, and population was the least. For soil total phosphorus, heterogeneity was the highest at the scale of topography and the smallest at the scale of rhizosphere, indicating topography and plant individual were the major factors affecting heterogeneity of soil total phosphorus, and the rhizosphere was the least.