Spatial variability of soil nutrients in wetland of Liangzi Lake

Understanding distribution of soil nutrients at the wetland is important for studying the ecological processes in wetland and wetland ecosystem function. However, soil nutrients are heterogeneous no matter in large scale or small scale wetland. With the wide application of GIS in the soil science, the soil nutrient spatial heterogeneity has aroused more and more attention in recent year. In order to study the spatial variability of soil nutrients in wetland of Liangzi Lake, an experimental site with area of 63.9 km~2 was selected to conduct the soil investigation. 101 soil surface (0—15cm) samples were collected at October in 2003, on a 400-by 400-m grid. Those soil samples were used for the measurement of (organic) matter, total N, total P, available N and available P. Based on spatial analysis function of GIS, spatial variability of soil nutrients in wetland of Liangzi Lake was studied using geostatistics. Theoretical semivariogram models of soil (organic) matter, total N, total P, available N and available P were spherical model with a sill. Soil properties varied sharply, among which CV of available P was highest, while CV of soil total P was the lowest with the values being 50.4% and 13.7%, respectively. Soil organic matter, total N, total P and available N were of spatial autocorrelation. The ratio of random variance (nugget) to total variance (sill) was 68.5% for soil organic matter, 68.3% for total N, 75% for total P, 71.5% for available N, respectively. The spatial autocorrelation of available P was lowest being 82.4%, no significant differences were found in the distance of spatial autocorrelation of these five soil nutrients, among which the distance of soil organic matter total N, total P, available N and available P was 2906.1 m, 2896.3 m, 2853 m, 2963.3 m and 2890.7 m, respectively. The map of Kringing interpolation indicated that the spatial distribution of those five soil nutrients were similar.