华北落叶松林土壤有机碳对择伐及人工更新的响应

Response of soil organic carbon to selective cutting and artifi cial regeneration in Larix principis-rupprechtii

通过研究择伐面积以及人工更新不同树种对华北落叶松低效林的土壤有机碳含量和碳密度的影响，为低效林的改造提供参考。2007年在华北落叶松低效林内进行3种不同面积的择伐，即0.02、0.03和0.05 hm2，并在择伐孔内人工更新白桦和华北落叶松2种树种，2012年测其土壤有机含碳量和碳密度。结果表明：同一择伐面积下，人工更新华北落叶松的土壤含碳量和碳密度均比白桦高，即异龄纯林比针阔混交林高；人工更新白桦的各择伐孔内土壤有机碳含量和碳密度表现为0.02 hm2＞0.03 hm2＞0.05 hm2，栽植华北落叶松时表现为0.05 hm2＞0.02 hm2＞0.03 hm2；同一择伐孔内，土壤含碳量和碳密度均随着土层深度的增加而降低；对于0～30 cm土层来讲，更新树种的影响比择伐面积的影响大。

The purposeof this study is to provide references for transformation of low efifciency stands by research the influences on soil carbon content and carbon density aboutLarix principis-rupprechtii low efifciency stands which were treated with the selective cutting and artiifcial regeneration. The selective cuttings of three different areas were conducted inL.principis-rupprechtiilow function forest in 2007, which were 0.02 hm2, 0.03 hm2 and 0.05 hm2 respectively,Betula platyphylla andL. principis-rupprechtii seedlings were planted in the artiifcial regeneration zones of selective cutting areas. The soil organic carbon content and carbon density were determined in 2012. The results show that within the same selective cutting area, the soil organic carbon content and carbon density of artiifcial L. principis-rupprechtii were both higher than that ofBetula platyphylla, this means that the carbon content and density of uneven-agedpure stands were higher than those of mixed broadleaf-conifer forest; the organic carbon content and carbon density of the soil in artiifcial regenerationBetula platyphyllaforest in the selective cutting zones took an order： 0.02 hm2〉0.03 hm2〉0.05 hm2, that in the zones plantedL. principis-rupprechtii forest showed a sequence： 0.05 hm2〉0.02 hm2〉0.03 hm2; In the same selective cutting zone, the soil carbon content and density decreased with the increase of soil depth, for 0-30 cm soil layer, the influence of tree species which were treated with artiifcial regeneration was bigger than selective cutting zones.