| In this paper,different pruning intensity treatments of mixed forests of Castanopsis hystrix and Pinus massoniana were taken as research objects,and four different pruning treatments were set up,which were pruning and repairing at 1/3,1/2 and 2/3 of the trunk.Branch(control group),by measuring the growth of tree height,diameter,volume accumulation and biomass accumulation,soil physical,soil nutrient and soil enzyme activity,explore the different pruning intensity on forest growth index,soil Physical property,soil nutrient,soil enzyme activity and the impact of forest light environment,thus providing a theoretical basis for the accurate improvement of the quality of Castanopsis hystrix and massoniana Lamb plantation..The research results are as follows:(1)After the pruning treatment,the growth indexes of diameter,tree height,branch height,volume,accumulation and biomass showed significant differences compared with the control group.Castanopsis hystrix Miq continued to rise with the increase of pruning intensity.The trend reached the maximum at the maximum pruning strength(2/3 tree height),but pruning had an inhibitory effect on the growth of Castanopsis hystrix Miq;the growth effect of Pinus massoniana Lamb was different,including diameter,tree height,volume,andaccumulation.The four growth indexes increased with the improvement of pruning strength after pruning,and the growth effect was best under 1/2 pruning strength,2/3 pruning strength is reduced compared to 1/3,1/2 pruning strength.The height of the branches and the crown width showed a continuous growth trend with the increase of the pruning intensity.(2)Different pruning strength had significant effects on soil bulk density and soil porosity.Pruning treatment reduced soil bulk density,soil bulk density and porosity were significantly negatively correlated,2/3 pruning intensity,soil bulk density reached a minimum of 1.47 g/cm3,different pruning strength significantly increased capillary porosity,non-hairy porosity,total porosity,forest soil layer became loose,increased soil aeration,and was conducive to forest root growth.The soil nutrient difference was significant in different stands,and the 2/3 pruning strength was conducive to the enrichment of soil total N and available P content;1/2 pruning intensity was conducive to the enrichment of ammonia N,P and K content.The pruning treatment is not conducive to the enrichment of the available K content.Different pruning strengths had significant effects on soil invertase,soil catalase,soil urease,and soil acid phosphatase activity.The 2/3 pruning strength of invertase and acid phosphatase activities were the highest,36.85 U/g·24h,1.38 U/g·24h,1/2 pruning strength urease and catalase had the highest activity,1.21 U/g·24h,1.22 U/g·24h,respectively.The enzymatic activity of the surface soil is greater than that of the deep soil.(3)Pruning can significantly change the light environment of the stand,anddifferent pruning intensity can significantly affect the leaf area index,average leaf inclination and light transmittance.The leaf area index of 2/3 pruning intensity was the smallest,4.93,and the average leaf dip angle and light transmittance of 2/3 pruning intensity reached the maximum,which were 76.29°and 16.93%,respectively.Considering the relationship between the overall pruning strength and the forest,the Castanopsis hystrix grows best under severe pruning(2/3 tree height),and the effect of each pruning intensity on the growth of Castanopsis hystrix is as follows: CK(control group)<1/3<1/2<2/3;Pinus massoniana grows best under moderate pruning(1/2 tree height),and the effect of each pruning intensity on the growth of Pinus massoniana is as follows: CK(control group)<2/3<1/3<1/2. |
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