华北农牧交错带农田-草地界面土壤水分的空间特征

利用经典统计与地统计学方法，对华北农牧交错带农田-草地界面不同采样粒度（1 m×1 m、2 m×2 m）0～50 cm土层土壤水分的空间异质性进行了分析.结果表明：研究区农田、草地、农田-草地界面土壤水分均属中等变异，草地土壤水分的变异系数较农田大；土壤水分的变异系数随土层深度的增加而逐渐增大，且1 m×1 m采样粒度下农田-草地界面土壤水分变异系数与土壤深度呈显著相关(P＜0.05)；1 m×1 m采样粒度下，农田-草地界面各土层土壤水分的空间异质性明显高于邻近的农田和草地，表现为中度到强度的空间自相关性，变程在7.65～30.99 m，且具斑块分布格局；2 m×2 m采样粒度下，农田-草地界面各土层土壤水分的空间结构既有中到强度的空间自相关性，又有完全随机化的纯块金效应，变程在4.16～18.86 m；在农田-草地边界存在土壤水分的界面效应.

Spatial pattern of soil moisture at the cropland-grassland boundary in agro-pastoral transitional zone of North China

By the methods of classic statistics and geostatistics,this paper analyzed the spatial heterogeneity of soil moisture at 0-50 cm depth in different sampling grain sizes(1 m × 1 m and 2 m ×2 m)at the cropland-grassland boundary in agro-pastoral transitional zone of North China.In study area,the soil moisture at 0-10 cm,10-20 cm,20-30 cm,30-40 cm,and 40-50 cm depths of cropland,grassland,and cropland-grassland boundary presented moderate variance,and the coefficient of variation(CV)of grassland was higher than that of cropland.The CV increased with soil depth,and a significant linear regression relation(P <0.05)was observed between them in sampling grain size 1 m × 1 m.In sampling grain size 1 m × 1 m,the spatial heterogeneity of soil moisture at different depths was obviously higher at cropland-grassland boundary than in cropland and grassland,which had a moderate to strong spatial dependency,and the range(A0)was 7.65-30.99 m; whereas in sampling grain size 2 m × 2 m,the spatial distribution of soil moisture at cropland-grassland boundary had both the moderate to strong spatial dependency and the pure nugget effect,and the A0was 4.16-18.86 m,suggesting that there existed ecological edge effect of soil moisture at cropland grassland boundary.