中文摘要：

为揭示砍伐干扰对森林土壤有效氮（NO3^-N和NH4^＋-N）含量空间异质性的影响,并为进一步认识森林生态系统N素循环及森林系统结构和功能提供基础依据.选取华北落叶松砍伐干扰林分（样地A）和未砍伐干扰林分（样地B）,采用基于地统计学中区域化变量理论的格局分析方法,对样地林下土壤（0～30cm）有效氮含量的空间异质性特征进行了对比研究.结果表明,未砍伐干扰林分（样地B）的土壤硝态氮和铵态氮含量分别为0.25mg·kg^-1和1.96mg·kg^-1,在一定尺度范围内呈现明显的空间自相关变异.砍伐干扰林分（样地A）的土壤硝态氮和铵态氮含量明显增加（0.85mg·kg^-1和3.36mg·kg^-1）,空间变异程度加大,且随机性变异所占的比例增加.样地A与样地B不同土层的土壤硝态氮和铵态氮含量差异显著（p〈0.05）.土壤硝态氮和铵态氮垂直分布均表现为随土层深度的增加,空间异质性降低.未砍伐干扰林分（样地B）不同土层铵态氮占总有效氮含量的比例较高,且该比值在不同土层中较稳定.砍伐干扰对华北落叶松林下土壤硝态氮和铵态氮含量的空间异质性有很大的影响,林分受到砍伐干扰后,空间异质性程度增加;未砍伐干扰林分（样地B）在保持林地肥力和防止林地氮素流失方面的效果较砍伐干扰林分（样地A）好.

英文摘要：

The aim of this study was to build a theoretical basis of soil nitrogen cycle and structure and function in a forest ecosystem. This study was conducted in Larix principis-rupprechtii forests,located in Guandi Mountain,Shanxi Province,China. Two plots（32 m×32 m） were selected which represented disturbed and undisturbed stands. Based on the theory and methodology of spatial pattern analysis in geostatistics,samples soil cores （7.0 cm in diameter） were taken at three soil depths （0-10 cm,10-20 cm and 20-30 cm.）. The spatial heterogeneity of soil characteristics （NO3^--N and NH4^＋-N） was analyzed. Soil nitrate content and soil ammonium content were 0.25 mg·kg^-1 and 1.96 mg·kg^-1 in the undisturbed stand. After cutting disturbance,the concentration of both forms of nitrogen increased obviously （0.85 mg·kg^-1and 3.36 mg·kg^-1）. The spatial heterogeneity of soil nitrate and ammonium are larger in the disturbed stand,and the proportion of random variation increased. In different soil layers,the soil nitrate and soil ammonium contents changed significantly （p0.05）. Vertical differentiation appeared that spatial heterogeneity of soil nitrate and ammonium decreased with the increase in soil depth in two stands. The proportion of soil NH4^＋ content remained higher at all soil layers. The spatial heterogeneity of soil NO3^--N and NH4^＋-N are greatly affected by cutting disturbance. The undisturbed stand had better soil fertility and less nitrogen leaching.