内蒙古苏木山华北落叶松人工林土壤养分变化规律

Changes of soil nutrients for Larix princiois-rupprechtii plantation in Sumushan, Inner Mongolia

为探讨内蒙古苏木山华北落叶松人工林土壤养分状况,选择该林区4个林龄(17a、26a、37a、48a)华北落叶松人工林,对不同林龄、不同土层间的土壤化学性质进行综合比较,利用主成分分析和回归分析的方法,计算土壤养分综合指标值,构建林龄与土壤养分综合指标值的回归方程,分析土壤养分的变化规律。结果显示:随着林龄增加,土壤pH值逐渐降低,土壤存在酸化趋势;土壤全效养分以幼龄林时最高,中龄林、近熟林时达到最低;土壤速效养分中碱解氮在中龄林含量最高,而后随林龄增加而降低至成熟林时降至最低,速效磷、速效钾含量均随林龄增加而降低;空间分布上,土壤pH值随土层加深而升高,其他各养分指标均随土层加深而降低,在土壤上层较显著;所构建的回归方程决定系数为0.880,能够较好的反应出林龄与土壤养分综合指标间的关系;幼龄林(17a)、中龄林(26a)、近熟林(37a)、成熟林(48a)土壤养分指标综合得分分别为:0.945、0.069、-0.50、-0.509,幼龄林土壤养分最好,成熟林土壤养分最差。

The changes of soil chemical properties at different developmental stages(17,26,37,and 48 years old)of Larix princiois-rupprechtii plantations in the forest area of Sumushan in Inner Mongolia were analyzed.By the method of principal component analysis and regression analysis,the comprehensive index values of soil nutrients were calculated,and the regression equations of forest age and soil nutrient comprehensive index values were constructed to analyze the changes of soil nutrients.The results showed that with the increasing of stand age,the soil pH gradually declined,the soil chemical properties were deteriorated in the pre-mature stands with the growth of larch plantations.For example,the soil nitrogen,phosphorus,and potassium decreased.The regression coefficient of the constructed regression equation was 0.880,which can better reflect the relationship between forest age and soil nutrients.The integrated fertility indexes(IFI)of the soil were 0.945,0.069,-0.5 and-0.509.It was concluded that there is a trend of soil acidification and decline in larch plantation in this area,so corresponding measures should be taken to prevent it in the process of forest management.