北方农牧交错带沽源农田-草地界面土壤水热空间特征

农田-草地景观界面是我国北方农牧交错带景观组成部分,研究该界面生态特征的格局和过程是完善北方农牧交错带研究的热点领域.首次采用地统计学方法中的半变异函数、克里格插值估计、空间分布图等方法研究北方农牧交错带河北沽源地区的农田-草地界面(CGB)土壤水热的空间异质性和界面空间效应.结果表明:根据不同尺度下的土壤水热空间异质性各参数的变化趋势确定较为合理的采样粒度为 0.5m×0.5m;农田-草地界面0～20cm土层土壤含水量为中等变异,土壤温度为弱变异,不同采样粒度空间结构特征定量研究得到土壤水分变程范围(A_0)为2.93～15.4m,且为中到强度的异质性程度(MSH),土壤温度变程为3.75～20.99m,表现为强空间异质性;验证在农田-草地边界向两侧的一定范围内土壤水热存在过渡型界面效应,且具不同的生态梯度.该研究结果是认识农田-草地界面和进一步开展该界面功能研究的基础,对深入研究北方农牧交错带农田-草地界面非生物水热界面具有重要意义.

Spatial heterogeneity of moisture and temperature in soil across the cropland-grassland boundary in Guyuan of north agro-pastoral transition zone, China

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.