不同密度杂种落叶松人工林的土壤微生物变化特征

为进行杂种落叶松（Larix olgensis＋Larix kaempferi）人工林管理,通过实地调查与试验分析的方法,研究江山娇林场4种密度杂种落叶松人工林（林分1：密度2500株／hm2^;林分2：密度3300株／hm2^;林分3：密度3400株／hm^2;林分4：密度6600株／hm2）的土壤微生物变化特征。结果表明：1）不同密度杂种落叶松人工林之间,微生物总量与林分细菌数量顺序为林分2〉林分1〉林分3〉林分4;真菌数量顺序为林分1〉林分3〉林分4〉林分2;放线菌数量顺序为林分3〉林分2〉林分1〉林分4;2）各密度杂种落叶松人工林土壤微生物基本呈现随土层深度增加而逐渐降低的特征,林分1与林分2的降低幅度小于林分3与林分4的降低幅度;3）各密度杂种落叶松人工林土壤微生物总量和细菌数量随时间的变化基本呈现3个阶段,即缓慢增长阶段,快速增长阶段与下降阶段。真菌数量随时间变化呈现出林分1与林分2前期较后期低,林分3与林分4前期较后期高的特征;放线菌随时间变化呈现出林分2与林分3快速增长出现在中期,林分1与林分4初、后期高,中期低的特征;4）不同密度杂种落叶松人工林的微生物变化特征初步证明,4种密度幼龄阶段杂种落叶松人工林中,土壤微生物生存和发展状况最好的密度为2500与3300株／hm^2,较好的密度为4400株／hm^2,最差的密度为6600株／hm^2。研究成果可为杂种落叶松人工林栽培密度的选择提供科学依据。

Changes of soil microbiological properties of Larix olgensis +Larix kaempferi plantation with the different densities

For Larix olgensis + Larix kaempferi plantation management,through the spot investigation and experimental analysis,the change of soil microbiological properties in four densities of Larix olgensis + Larix kaempferi plantation was studied.The four sample stands were stand 1 with 2 500 trees per hectare,stand 2 with 3 300 trees per hectare,stand 3 with 4 400 trees per hectare and stand 4 with 6 600 trees per hectare.Results showed that 1) The quantity of total microorganism and bacteria in soil was in the decline order of stand 2,stand 1,stand 3 and stand 4;The quantity of fungus was in the decline order of stand 1,stand 3,stand 4 and stand 2;The quantity of actinomycetes was in the decline order of stand 3,stand 2,stand 1 and stand 4;2)The four densities of Larix olgensis + Larix kaempferi plantation had the same characteristic of reducing trend of microorganism quantity,that is the deeper the soil layer,the less the quantity of microorganism,and the decline degree of stand 1 and stand 2 was smaller than that of stand 3 and stand 4;3) The quantity change of microorganism and bacteria in every density of Larix olgensis + Larix kaempferi plantation can be classified into three stages,slow growth stage,fast growth stage and decline stage.The fungi quantity of stand 1 and stand 2 was larger in the early stage and less in the late stage.The fast growth stage of actinomycetes quantity of stand 2 and stand 3 presented in the middle stage,the actinomycetes quantity of stand 1 and stand 4 was larger in the early and late stage and less in the middle stage;4) To the young age of Larix olgensis + Larix kaempferi plantation,2 500-3 300 trees per hectare density was more suitable for the living and development of microorganism than 4 400 trees per hectare density,and 6 600 trees per hectare density was the worst density of all.This research would offer some scientific basis for choosing the density of the hybrid larch plantation.