基于植物多样性和土壤理化性质的马尾松混交林质量评价OA

In order to provide theoretical basis for improvement of low-quality and low-efficiency plantations of Pinus massoniana in Guangxi,taking mixed plantations of over-mature P.massoniana with Michelia macclurei,Mytilaria laosensis,Castanopsis hystrix and Xanthostemon chrysanthus as research objects,taking P.massoni-ana pure plantation as control,understory plant composition and diversity as well as soil physical and chemical properties in different mixed plantations were analyzed.Qualities of mixed plantations were comprehensively evaluated.Results showed that total number of understory plants in four mixed plantations were higher than that in P.massoniana pure plantation.Top three most important plants in shrub layer differed in four mixed planta-tions,while the most important plants in herb layer was consistently Dicranopteris linearis,but their importance values were lower than those in P.massoniana pure plantation.Margalef richness indexes of shrub layers in P.massoniana×M.macclurei and P.massoniana×M.laosensis mixed plantations were significantly higher than those in other plantations,and Shannon-Wiener indexes,Simpson indexes,Pielou evenness indexes and Mar-galef richness indexes of herb layers in these two mixed plantations were significantly higher than those in other plantations.In 0-20 cm soil layer,P.massoniana pure plantation had the highest soil bulk density and capil-lary porosity,while P.massoniana×M.laosensis mixed plantation had the highest total porosity.In 20-40 cm soil layer,P.massoniana×M.laosensis mixed plantation had the highest soil bulk density,while P.massoniana pure plantation had the highest capillary porosity and total porosity.In 0-20 and 20-40 cm soil layers,soil pH as well as contents of organic carbon,total nitrogen,total phosphorus and total potassium in four mixed planta-tions were higher than those in P.massoniana pure plantaion.There were no significant correlations among un-derstory plant diversity indexes and soil physical and chemical properties.Comprehensive evaluation of stand quality indicated that P.massoniana×M.macclurei and P.massoniana×C.hystrix mixed plantations were recom-mendable planting models for promotion.