不同坡向油松人工林建群种种群结构及群落特征分析

【目的】阐明黄土高原森林区不同坡向对油松人工林建群种种群结构及群落特征的影响，为黄土高原地区油松人工林天然化发育的生境选择及合理经营提供依据。【方法】选择黄龙山生长于阴坡、阳坡的油松人工林，于造林后10，30（间伐1次）和45年（间伐2次）对其建群种的种群结构、幼苗更新、物种多样性、土壤养分特征进行调查和综合比较分析。【结果】10年生油松人工林种群在阴坡、阳坡样地上的种群结构、幼苗更新和群落特征没有明显差异；经过1次间伐的30年生油松人工林，阴坡林木的生长量、物种多样性及土壤养分速效P、硝态N、铵态N含量显著高于阳坡；经过2次间伐的45年生油松人工林，其在阴坡、阳坡的平均胸径差异不显著，但阴坡有少量较大胸径的林木，且林木平均高度、油松幼苗更新数量、土壤养分、灌木物种的丰富度及多样性指数均显著高于阳坡。【结论】从持续发育角度看，黄龙山林区阴坡和阳坡均适合油松人工林培育，阴坡优于阳坡。及时抚育可以促进油松人工林的持续发育。

Analysis of population structure and plantation community characteristics of Pinus tabulaeformis plantations in Loess Plateau in different slope

【Objective】The study was to illustrate the effect of slop on the population structure and community characteristics,and to provide reference for proper choosing habitat and management.【Method】Diameter-class structures,height-class structures,natural regeneration of seedling,species diversity,soil bulk density and nutrient were analyzed based on an investigation of Pinus tabulaeformis plantations in Huanglong Shaanxi.The trees were planted 10,30,45 years ago on the sunny and shady slope,and the 30-year-old plantations were thinned once,the 45-year-old plantations twice.【Result】The population structure,seedling regeneration and community characteristics of 10-years old P.tabulaeformis plantations have no significant difference.On the opposite,the growth situation,species diversity,the contents of available P,NH+4-N and NO-3-N of 30-year-old P.tabulaeformis plantations(thinned once) have significant differences,in which shady slope is higher than sunny slope.The differences of tree height on the sunny and shady slope in the 45-year-old P.tabulaeformis plantations(thinned twice) are not significant.There are big diameter individuals on the shady slope.Average tree height,natural regeneration of seedling,species diversity and soil quality on the shady slope are obviously higher than on the sunny slope in the 45-year-old P.tabulaeformis plantations.【Conclusion】Huanglong forest region is suitable for planting P.tabulaeformis both on the sunny and shady slope,but the shady slope has better site condition for sustainable development.Timely tending can promote the continuous development of P.tabulaeformis plantation.