黄土高原中部半湿润丘陵区不同树种林地土壤团聚特征的比较

目的]研究不同树种森林植被对土壤团聚特征的影响。方法]以地处黄土高原中部半湿润丘陵区的黄陵县双龙林场为对象,研究了不同树种针阔叶纯林和混交林土壤的团聚体数量特征、团聚体的水稳性特征及团聚体水稳性与腐殖质组成的关系。结果]不同林地土壤团聚体的分形维数为2.21～2.54,重量平均直径为2.07～4.86mm,几何平均直径为1.04～1.69mm,粒径均匀度指数为0.76～0.97,分形维数的大小顺序依次为华山松×辽东栎〉华北落叶松〉侧柏×辽东栎〉华山松〉白桦和油松〉侧柏〉刺槐×油松〉油松×辽东栎〉刺槐。土壤团聚体的水稳性指数为14.28～24.77,针阔混交林地土壤团聚体水稳性在0.01水平显著大于相应树种纯林土壤团聚体水稳性（侧柏除外）,纯林林地土壤团聚体水稳性指数的大小顺序为侧柏〉华山松〉油松〉华北落叶松〉白桦〉刺槐。土壤团聚体水稳性与有机碳质量分数相关性在0.05水平显著。通径分析表明,腐殖质中的富啡酸对土壤团聚体的水稳性贡献最大,胡敏酸对土壤团聚体的水稳性起了较大的制约作用。结论]该地区营造侧柏和华山松林有利于提高土壤团聚体的水稳性,二者可以作为防护林和用材林的首选树种。

Comparison of Soil Aggregates Characteristics in Different Tree Species Forests in Semi-humid Hilly Region, Central Loess Plateau

Objective] The research aimed to study the effects of different tree species on soil aggregation.Method] Soil aggregates quantitative characteristics,water stability and the relationship between water stability and humus compositions of typical coniferous forest,mixed forest and broadleaf forest in Shuanglong forest farm in central Loess Plateau were studied.Result] Soil aggregates fractal dimension was between 2.51 and 2.54.Mean weight diameter was between 2.07 and 4.86 mm.Geography mean diameter was between 1.04 and 1.69 mm.Soil particles evenness index was between 0.76 and 0.97 and it was useful in representing soil aggregates characteristics.The fractal Dimension followed this order armand pine×liaodong oak>north china larch>chinese arborvitae×liaodong oak>armand pine>birch and chinese pine>chinese arborvitae>black locust×chinese pine>chinese pine×liaodong oak>black locust.Soil aggregate stability index ranged from 14.28 to 24.77.It in mixed forest was significantly greater than that in corresponding pure forest(except chinese arborvitae).Soil aggregate stability index in pure forest followed this order chinese arborvitae> armand pine>chinese pine>north china larch>birch>black locust.Soil aggregates water stability had significant correlation with organic carbon.Fulvic acid gave the greatest contribution to soil aggregates water stability,however humic acid restricted soil aggregates water stability.Conclusion]The optimum afforestation mode in this region was chinese arborvitae and armand pine which could improve soil aggregates stability.They could be used in ecological forest and timber forest.