密度调控对华北落叶松人工林土壤有机碳及养分特征的影响

以华北落叶松人工林为对象,研究不同林分密度下(分别为740、1480、2000和2170株.hm-2)各土层的土壤有机碳含量、有机碳密度、养分特征以及它们之间的相关关系。结果表明:土壤有机碳含量及碳密度随着土壤深度增加而减少,呈明显的垂直分布特征;当林分密度增大到2170株.hm-2时,土壤有机碳含量及碳密度显著增加至最大,分别为25.45g.kg-1和15.68kg.m-2,并与740株.hm-2林地土壤有机碳含量及碳密度差异显著。当林分密度由740株.hm-2增加到2170株.hm-2时,各种养分变化规律不尽一致,但当林分密度为2170株.hm-2时,0-60cm深度的土壤全氮、全磷及速效钾含量均保持在一个相对较高的水平,而土壤全钾和有效磷含量仅在0-20cm土层较高。对于落叶松人工林地整个土壤剖面,土壤有机碳含量及碳密度与土壤全氮、全磷、速效钾含量均呈显著或极显著正相关。从林地土壤固碳的角度,建议将华北落叶松人工林的林分密度控制在2170株.hm-2。

Effects of Larix principis-rupprechtii plantation density control on soil organic carbon and nutrients characteristics

The Larix principis-rupprechtii plantations of different stand densities(740,1480,2000 and 2170 tree·hm-2,respectively) in rocky mountain area of northern China were selected to study SOC content and density,nutrient characteristics and their correlations.The results were showed as the followings: 1) With the increase of soil depth,SOC content and density decreased significantly;2) When the stand density increased to 2170 trees·hm-2,the SOC content and density reached the maximum of 25.45g·kg-1 and 15.68kg·m-2,respectively,and there existed significant differences between 2170 trees·hm-2 and 740 trees·hm-2;3) The variations of nutrients were not consistent when the stand density increased from 740 trees·hm-2 to 2170 trees·hm-2.At the stand density of 2170 trees·hm-2,total N,total P and rapidly available K contents were in relatively higher levels in the soil depth of 0-60cm,but higher contents of total K and available P were only found in the depth of 0-20cm;4) In the whole soil profile,the SOC content and density had very significant or significant positive correlations with total N,total P and rapidly available K contents;5) The stand density of Larix principis-rupprechtii plantation was suggested to be about 2170 trees·hm-2 for the soil carbon sequestration.