Spatial heterogeneity of moisture and temperature in soil across the cropland-grassland boundary in Guyuan of north agro-pastoral transition zone, China
Abstract:Ecological boundary studies including ecological pattern and process are hot topics in the contemporary ecology. In the north agro-pastoral transition zone of China, there are plenty of mosaic patterns of cropland and grassland with a core part mosaic of cropland-grassland boundary(CGB). In the study of spatial pattern of soil moisture (Msoil) and soil temperature (Tsoil) at CGB, geostatistical techniques were used to quantify the spatial heterogeneity and to delineate the spatial pattern of Msoil and Tsoil of the CGB inside these mosaics. Results were summarized as follows. More information of ecological process for Msoil and Tsoil were obtained in the smaller sampling grain size of 0.5m×0.5m. At the CGB, the CV (Coefficient of variation) of 0-20cm deep Msoil showed moderate, while the Tsoil was low. The “range A0” of Msoil was from 2.93 to 15.4 m and the MSH (Magnitude of spatial Heterogeneity ) exhibited from moderate to high spatial dependency, whereas the “range A0” of Tsoil was 3.75-20.9m and the MSH was high spatial dependency. The parameters of MSH and the range A0 for Msoil and Tsoil across the CGB were quantified, and further, the spatial patterns for Msoil and Tsoil were delineated within a certain range across the CGB, demonstrating that there exists the gradual ecological edge effects and the different spatial ecological gradients effects for Msoil and Tsoil. The results here provide the initial data of the spatial structure for Msoil and Tsoil in the CGB. The further understanding of ecological process and structure for soil attributes of CGB is needed and crucial in the fragmented land of agro-pastoral transition zone.