红松针阔混交林林隙土壤总有机碳和易氧化有机碳的时空异质性研究

Spatiotemporal Heterogeneity of Soil Total Organic Carbon and Easily Oxidizable Organic Carbon in the Forest Gaps of Pinus koraiensis-dominated Broadleaved Mixed Forest

在小兴安岭原始红松针阔混交林内选择3个代表性的林隙作为试验样地，采用网格法布设采样点。在生长季节内，对表层土壤（0-20cm）总有机碳（TOC）和易氧化有机碳（EOC）的含量进行连续测定。采用经典统计学和地统计学相结合的方法，分析两者的时空异质性。结果表明：土壤TOC和EOC随时间变化显著，8月份含量均较高，不同林隙间变化规律不同；土壤TOc（变异系数CV为28．7％～41．8％）和EOC（CV为21．0％～61．6％）均存在空间异质性，其变异均属于中等程度变异；结构比显示它们均具有强烈的空间自相关性（结构比〉75％），主要由结构性因素引起；等值线图表明，林隙表层土壤TOC和EOC具有块状或连续分布的特点，不同林隙间差异较大，TOC的空间分布格局随时间变化较大，而EOC的分布格局相对稳定，受地形影响较大。

Three representative forest gaps were selected as experimental plots in Pinus teoraiensis-dominated broadleaved mixed virgin forest in Xiao Xing＇an Mountains. Sampling points were set up by the grid method. The content of soil total organic carbon （TOC） and easily oxidizable carbon （EOC） in surface soil layer （0-- 20 cm） were measured periodically during the growing seasons. Spatiotemporal heterogeneity of TOC and EOC were analysed by the combined methods of the traditional statistics and geostatistics. The results showed that：Soil TOC and EOC changed substantially over time, both reached higher content in August, the change rule of TOC and EOC of different forest gaps were clearly different. Variations of soil TOG （coeffi- cient of variation （CV） was between 28.7% and 41.7%） and EOC（CV was between 21.0% and 61.0%） fell into moderately spatial variability. According to the spatial proportion [C/（Co ＋C）], both TOC and EOC had strongly spatial autocorrelation （i. e. , their spatial proportions were higher than 75%） and were mainly caused by structural factors. The contour maps indicated that TOC and EOC in surface soil layer had the characteristics of patchy or continuous distribution, and presented relatively larger variation in different for est gaps, the spatial distribution of TOC varied significantly over time, but that of EOC was relativtly stable compared with that of TOC, effected by topography considerably.