东北近天然林土壤可蚀性K值研究

基于吉林省汪清林业局所辖林场10块近天然林样地,采集0—20,20—40和40—60cm土层土壤样品,对土样进行了粒径分析及养分测定。运用侵蚀—土地生产力影响评估模型(EPIC)对研究区土壤可蚀性因子K值进行了估算,分析讨论了K值的影响因素及其与土壤养分之间的相关性。结果表明,研究区内土壤可蚀性K值平均为0.060 7t·hm2·h/(MJ·mm·hm2);0—20cm深度的土壤可蚀性K值较20—60cm土层土壤大,针阔混交林的K值比阔叶混交林的大;当林分密度小于1 200株/hm2,郁闭度小于0.75时,K值随林分密度和郁闭度的增大而减小。K值与土壤养分的相关性由高到低依次为:全氮速效钾有效磷全磷,除全氮外其他土壤养分均与K值呈负相关。最适林分密度为750~1 200株/hm2,在该密度下各土壤养分含量状况较好且土壤抗蚀能力较高。

Soil Erodibility K-Value of Semi-natural Forests in Northeast China

The soil particle size distribution and soil nutrients contents in the soil depth of 0-20 cm, 20-40 cm and 40-60 cm were analyzed, the soil sampling got from ten semi-natural forest plots in forest farms of Wangqing Forestry Bureau, Jilin Province. In addition, the soil erodibility K-value in this region was investigated with the formula calculation method of EPIC(erosion productivity impact calculator) and its affecting factors, the correlation between K-value and soil nutrients were discussed. The results indicated that the mean K-value was 0.060 7 t·hm²·h/(MJ·mm·hm²). The K-value at the soil depth of 0-20 cm was higher than that at 20-60 cm. Higher K-values were found in coniferous and broad-leaved mixed forest than broad-leaved mixed forest. The K-value decreased with increasing stand density and canopy density when stand density was less than 1 200 hm² and canopy density less than 0.75. The correlations between K-value and soil nutrients were in a descending order of total nitrogen, readily available potassium, available phosphorus and total phosphorus in the study area. All soil nutrients were negatively correlated with K-value except total nitrogen. The optimal stand density was about 750~1 200 trees/hm² with higher soil nutrient concentrations and soil anti-erodibility.