不同造林模式对桉树生长和土壤理化性质的影响

[Objective]To investigate the effects of different silvicultural modes on the growth of eucalyptus trees and soil physicochemical properties,and to explore the best mixed silvicultural mode.[Method]The growth indexes and soil physical and chemical properties of Eucalyptus megacephalus were measured and analyzed in three plantation models,namely,treatment 1(Eucalyptus grandis×E.urophylla pure forest),treatment 2(Eucalyptus grandis×E.urophylla×Machilus pauhoi mixed model),and treatment 3(Eucalyptus grandis×E.urophylla×Castanopsis hystrix mixed model).[Result]The results showed that the companion species of Machilus pauhoi and Castanopsis hystrix had a significant effect on Eucalyptus grandis×E.urophylla tree height,diameter at breast height,volume of wood per plant and volume of stock.The tree height,diameter at breast height,volume of timber per plant and volume of standing stock of Eucalyptus grandis×E.urophylla in Treatment 2(Eucalyptus grandis×E.urophylla×Machilus pauhoi mixed model)were 18.16%,14.72%,36.84%and 39.93%larger than those in Treatment 1(Eucalyptus grandis×E.urophylla pure forest),respectively,and the differences were all significant(P<0.05,the same as below).The tree height,diameter at breast height,volume of wood per plant and volume of storage of Eucalyptus grandis×E.urophylla in treatment 3(Eucalyptus grandis×E.urophylla×Castanopsis hystrix mixed model)were 13.40%,16.02%,29.41%and 34.64%higher than that in treatment 1(Eucalyptus grandis×E.urophylla pure forest),and the differences were all significant.As the soil depth increased,the soil bulk density became larger,and the total soil porosity and soil capillary porosity became smaller.The soil capacity of Eucalyptus grandis×E.urophylla pure forest at different soil depths was greater than that of the other two hybrid models,and was the smallest in treatment 3(Eucalyptus grandis×E.urophylla×Castanopsis hystrix mixed model),while the total soil porosity,soil trubular porosity,and water holding capacity of Eucalyptus grandis×E.urophylla pure forest in the field were smaller than that of the other two hybrid models,and was the largest in treatment 3(Eucalyptus grandis×E.urophylla×Castanopsis hystrix mixed model).With the exception of treatment 3(Eucalyptus grandis×E.urophylla×Castanopsis hystrix mixed model),soil total nitrogen in the other model types showed an increasing trend with increasing soil depth,while soil quick nitrogen content,soil total phosphorus,total potassium,quick nitrogen,quick phosphorus,quick potassium,organic matter,effective copper,effective iron,effective zinc and effective boron showed a decreasing trend with increasing soil depth.The content of bulk and trace elements and organic matter in the soil was higher than that of Eucalyptus grandis×E.urophylla pure forest in all mixing patterns.With the exception of soil capacity,all indicators were positively correlated with Eucalyptus grandis×E.urophylla growth indicators,and some of them were significantly or very significantly positively correlated.[Conclusion]In summary,both mixing patterns can increase the growth of Eucalyptus grandis×E.urophylla and improve the soil quality,but from the point of view of growth indexes,the silvicultural pattern of treatment 2(Eucalyptus grandis×E.urophylla×Machilus pauhoi mixed model)is more favorable to the growth of Eucalyptus grandis×E.urophylla.