Abstract:Sampling plots were established by the method of grids in a forest gap and closed forest of Pinus koraiensis-dominated broadleaved mixed forests in Xiaoxing’anling Mountains, the volumetric soil water content (SWC) in I~III soil layers in medium and small gaps was measured by using time domain reflectometry 200 (TDR 200) during the period of July and September, 2010. The basic characteristics of SWC in each soil layer and the difference in SWC among various sampling locations in the same gap were analyzed by traditional statistics and geostatistical methods, Kriging interpolating was performed and the spatial distribution maps of SWC were drawn by using surfer 8.0 software, the spatiotemporal heterogeneity of SWC in the gaps was analyzed. The aim of this study was to provide the theoretical basis and data support for further studies on soil physical properties, gap regeneration and sustainable management of Pinus koraiensis-dominated broadleaved mixed forest. The results showed that SWC in I~III soil layers in medium and small gaps fell into moderate variation. With increased soil depth, the SWC and patch connection degree increased. The maximum SWC occurred in the area in and around gap center, and this area expanded and approached to the gap center with increased soil depth. However, the minimum SWC appeared within the expanded gaps and closed forest. For medium and small gaps, the difference in SWC in layer II among respective gap center and its edge was larger than that in layer I and layer III. Between July and September, the mean SWC exhibited single-peak variation, larger in medium gap than in small gap, the maximum appeared in August. The SWC in layer I and II in September decreased substantially than that in August, but there was slightly variation in layer III in September as compared with that in August.