阔叶红松混交林不同大小林隙土壤含水量的时空异质性

在小兴安岭阔叶红松(Pinus koraiensis)混交林林隙及其周围郁闭林分内,通过网格法布点,于2010年7—9月使用TDR200测定中、小林隙I III层的土壤含水量。运用经典统计学和地统计学方法分析各土层土壤含水量的基本特征及同一林隙各样点土壤含水量的差异性,利用surfer 8.0软件进行克立格空间局部插值,并绘制各土层土壤含水量空间分布图,分析林隙土壤含水量的时空异质性。结果表明:中、小林隙I III土层土壤含水量均呈中等程度变异。随着土层深度的增加,土壤含水量提高,土壤含水量的斑块连接度增大。土壤含水量最大值出现在林隙中心和近中心区域,并呈现出随土层深度增加面积扩大并向中心靠拢的变化趋势;土壤含水量最小值出现在扩展林隙及其郁闭林分内。中、小林隙中心与边缘土壤含水量的差异均为II层较I和III层大。7—9月土壤含水量均值呈单峰型变化,最大值出现在8月,且中林隙土壤含水量较小林隙的大;9月I和II层土壤含水量较8月大幅度减小,但III层与8月相比差异较小。

Spatiotemporal Heterogeneity of Soil Water Content at Different Size of Gaps of Pinus koraiensis-Dominated Broadleaved Mixed Forest

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 IIII 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 IIII 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.