| Phoebe bournei is a precious timber species,a national level 2 protect trees species.However,the growth of Phoebe bournei is slow,most of the Phoebe bournei plantations built in southern provinces of China are young and middle-aged stands,and the growth generally poor.So how to cultivate Phoebe bournei plantation into large diameter timber is the main problem of Phoebe bournei cultivation.In order to explore the management of Phoebe bournei stands,farther more to cultivating large diameter timber of Phoebe bournei.This paper,on the basis of the Phoebe bournei plantations of Youxi state-owned forest farm in Fujian Province,we choices the superior trees(dominant trees and sub-dominant trees)from the Phoebe bournei plantations which growth well for comprehensive tending experiments of deep plowing,fertilization and mulching straw.The whole experiment is made up of 4 parts,they all orthogonal design with three factors and three levels orthogonal experiment:Experiment 1(comprehensive tending experiment of deep plowing,applying compound fertilizer and mulching straw in dominant trees);Experiment 2(comprehensive tending experiment of deep plowing,applying compound fertilizer and mulching straw in sub-dominant trees);Experiment 3(comprehensive tending experiment of deep plowing,applying urea and mulching straw in dominant trees);Experiment 4(comprehensive tending experiment of deep plowing,applying urea and mulching straw in sub-dominant trees).The main findings are as follows:(1)The comprehensive tending effect of deep plowing,fertilization and mulching straw was better in superior individual(dominant and sub-dominant trees).Among the four experiments,the tree without deep plowing,fertilization and mulching straw had the lowest increment in DBH,height and volume,it indicate that if no tending measures were taken in the Phoebe bournei middle-aged stands,it growth was very slow.Contrary adopting a number of comprehensive tending operations could effectively promote the growth of trees.So comprehensive tending operations is an important measure of forest management for Phoebe bournei stand,and also a great significance for cultivating large diameter timber of Phoebe bournei.(2)The effect between deep plowing,fertilization,mulching straw showed the characteristics of deep plowing>fertilization>mulching straw.It means deep plowing can great promote the growth of Phoebe bournei.Deep plowing makes the topsoil turn over,turning the fertile topsoil to the ground,which is beneficial to the absorption of Phoebe bournei.root system;more importantly,it improves the soil structure,loosens the soil,enhances the soil porosity,facilitates the precipitation to enter the soil,enhances the soil moisture content,and is conducive to the growth of Phoebe bournei.In four experiments,the growth of DBH,tree height and volume showed the characteristics of deep plowing 16m2/tree>9m2/tree>Om2/tree,and the difference reach significant level(P<0.05)in variance analysis.The larger the area of deep plowing,the growth better,generally in 9m2/tree-16m2/tree,the specific size of the area depends on the crown size.The effect of deep plowing on growth can generally be maintained for 3-5 years,so deep plowing can be carried out every 5 years or so in the cultivation of large diameter timber in Phoebe bournei.(3)The fertilization can promote for growth of Phoebe bournei.With the stand growth of Phoebe bournei from young forest become mid-mature,the consumption of soil nutrients is increasing.However,Phoebe bournei plantation has poor leaf litter,slow decomposition and poor self-fertilization ability.In order to promote the growth of Phoebe bournei,artificial fertilization is an effective measure to increase the soil nutrient content and ensure the normal growth of Phoebe bournei.The DBH,tree height and volume growth of Phoebe bournei in the four experiments were mostly 2kg/tree>lkg/tree>0kg/tree,but the variance analysis did not reach significant difference(P>0.05).Comparing with experiment 1,2,3 and 4,the applying of compound fertilizer and urea can effectively promote the growth of Phoebe bournei.The effect of fertilization on the growth of trees can generally be maintained for 2-3 years,so it can be applied every 3 years or so in the process of cultivating large diameter timber of Phoebe bournei.(4)Mulching straw had little effect on the growth of Phoebe bournei.The effect of mulching straw is to keep the soil loosening and facilitate rainfall moisture to enter the soil more easily,thus increasing the soil moisture content.From this experiment,it found that straw was easy to decayed,and the mulching straw basically decayed within 3-5 months,so the maintenance time was very short,and the effect was small.From the growth of DBH,tree height and volume of Phoebe bournei,the results showed that experiment 1 mulching straw 5kg/tree>Okg/tree>10kg/tree Experiment 2 mulching straw Okg/tree>5kg/tree>10kg/tree,Experiment 3 and Experiment 4 mulching straw lOkg/tree>5kg/tree>Okg/tree,four experiments showed different results,but the differences of the three small(P>0.05),so mulching straw had little effect on growth of Phoebe bourmei.(5)The dominant and sub-dominant trees are hopeful to grow into large diameter timber.The results of four experiments showed that the comprehensive tending of deep plowing,fertilization and mulching straw could effectively promote the growth of dominant and sub-dominant trees.The absolute growth of dominant trees was greater than that of sub-dominant trees,but the relative growth(growth rate)of sub-dominant trees was greater than that of dominant trees.In conclusion,deep plowing can promote the growth of trees for 3-5 years,and fertilization can reach 2-3 years at a time.The comprehensive tending operations experiment in superior individual trees(dominant and sub-dominant trees)with deep plowing + fertilization + mulching straw can effectively promote the growth of DBH,tree height and volume of Phoebe bournei.The comprehensive tending of 9-16m2/tree + fertilizer 1-2kg/tree in every 3-5 years can promote the sustainability growth.then grow into large diameter timber,and also can be applied in production. |
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