Abstract: The spatial distributions of total N, available P, N/P ratio and biomass were analyzed on Gannan plateau based on observed data combined with the geostatistic method. Results showed that the N/P ratio of soil at 15~30 cm layer and 30~60 cm layer had greater spatial variability. With the increase of soil depth, the variations of total N and N/P ratio increased, whereas the variation of available P increased at first then decreased. N/P ratios in soil of Ganna plateau increased gradually from west to east as well as from north to south. N/P ratios in soil reduced gradually with the increase of soil depth, whereas the spatial autocorrelation of N/P ratios increased at first then decreased. Spatial autocorrelation of total N and available P decreased with soil depth increased. The spatial heterogeneity of N/P ratios in soil was influenced by altitude and vegetation to some extent. With rising elevation, N/P ratios in soil of Ganna plateau reduced gradually. However, N/P ratios in soil of alpine shrub meadow and alpine meadow were relatively stable as spatial heterogeneity increased slowly with increased soil depth.

Key words: Soil N/P ratio, Variogram, Spatial heterogeneity

摘要： 土壤氮磷比是影响植被空间分布差异的主要原因,准确模拟分析土壤氮磷比的空间分布特征是改善土壤环境和指导农牧业生产的基础。基于地面实测数据,结合地统计学方法,分别分析了甘南高原土壤全氮、速效磷、氮磷比及地上生物量的空间分布特征。结果表明:在15~30 cm和30~60 cm土层中的土壤氮磷比具有较强的空间变异性;甘南高原土壤氮磷比由西向东、由北向南逐渐递增。随着土层深度的增加,土壤氮磷比逐渐降低,其空间自相关性呈现出先降低后增加的趋势。而全氮、速效磷的空间自相关性随土层深度增加而降低;土壤氮磷比的空间异质性在一定程度上受海拔和植被的影响;随着海拔的升高,土壤氮磷比逐渐降低。高寒灌丛草甸和高寒草甸2种草地类型的土壤氮磷比的空间异质性较非草地稳定。

关键词: 土壤氮磷比, 变异函数, 空间异质性