[Effects of gap size on the spatial heterogeneity of soil water in Pinus koraiensis-dominated broad-leaved mixed forest].

In August-October 2011, the soil water content (SWC) at different depths in different sized gaps in Pinus koraiensis-dominated broad-leaved mixed forest of Xiaoxing' an Mountains, Northeast China was continuously measured by grid nesting method and time domain reflectometry (TDR), and the spatial heterogeneity of the SWC was analyzed by the principles and approaches of geostatistics. The SWC was most abundant in medium gap, followed by in large gap and in small gap whereas the maximum difference of SWC was the biggest in large gap, followed by in medium gap, and in small gap. The variation range of the nugget of SWC at different depths in the large, medium, and small gaps was 0.001-0.404, 0.001-0.273, and 0.001-0.261, respectively. The SWC heterogeneity resulted from random part and the total system SWC spatial heterogeneity were decreased in the order of large gap > medium gap > small gap. The spatial distribution pattern of SWC was most complicated in medium gap, while the spatial dependence in the variation of the SWC pattern was the strongest in large gap. High-grade patches (SWC was 50%-60%) occupied the largest area in medium gap, followed by in large gap, and there was no high-grade patch in small gap. As for the SWC at same depths and in same months, its grade distribution was most simple in small gap, but relatively complicated in large and medium gaps. The maximum value of SWC increased with increasing gap size.