Productivity Evaluation Of Masson Pine Forest In Ziyun Autonomous Count

Nowadays,our country forestry is from expanding forest area of denotative development to improve the quality of forest gradually shift of connotative development,strengthening forest management,science to realize mass efficiency,give full play to the forest of a variety of production and service function has become a modern forestry construction of ecological civilization,development,and promoting scientific development of The Times.It is of great guiding significance to explore the relationship and internal law between forest growth and influencing factors,and to master the status of stand and productivity in different growth stages.Pinus Massoniana Lamb is the main tree species used for afforestation and timber in south China.It has the characteristics of fast growth,high yield and strong adaptability.It plays an important role in national economic development and plays an important role in maintaining ecological balance.The productivity and ecological benefit of many Pinus Massoniana forests are not high because of the phenomenon of heavy mountain closure and light afforestation.At present,Pinus Massoniana forest is difficult to meet the market demand for different levels,especially high quality and large diameter timber.In addition,the long-term use of single tree species pure forest management model,resulting in soil fertility decline,productivity decline,low species diversity,ecological function decline and other prominent problems.How to manage Pinus Massoniana plantation scientifically and effectively promote stand growth and productivity is an urgent problem to be solved in forestry production practice.Based on this,this study took Pinus Massoniana pine plantation in Ziyun Autonomous County of Guizhou Province as the research object,and evaluated the site quality and grade classification of Pinus Massoniana plantation in the county by using the small-class data of the fourth Forest Resources Planning and Design Survey.Site and at the same time,based on the coupled double factor experiment design typical sample investigation,the site quality which are rated low,medium and high three level,forest age 6years,16 years,26years,36 years four levels,a total of 12,5 samples each processing set to repeat,as the investigation for a total of 60 samples,sample area covers an area of 20 m x 20 m.Through comparative analysis of stand status and productivity changes of Pinus Massoniana plantations under different site quality grades and different stand ages,the key factors affecting productivity improvement of Pinus Massoniana plantations were identified.The main research results are as follows:(1)The modified Weibull model can be used to construct the polymorphic status index curve of masson pine plantation in Ziyun Autonomous County,and the fitting accuracy is 83.6%.The site quality of Pinus Massoniana plantation can be divided into three grades:low(GradeⅠ),medium(gradeⅡ)and high(gradeⅢ).The area of gradeⅠforest is 4853.19hm~2(34.42%),gradeⅡforest is 7914.6hm~2(52.86%),and gradeⅢforest is 2203.91hm~2(14.72%).The site quality of Pinus Massoniana plantation was mainly low and medium grade.(2)The vertical structure,horizontal structure,age structure,stand growth,stand renewal and tree health of Pinus Massoniana plantation were significantly affected by stand age(P<0.05),while site quality grade only had significant effect on age structure,and the interaction between stand age and site quality only had significant effect on age structure.It can be seen that stand age has more influence on stand status index than site quality grade.(3)Both site and stand age affected the biomass and productivity of Pinus Massoniana plantation.The biomass of stand increased gradually with the increase of stand age and site quality grade,while the productivity decreased gradually with the increase of stand age,and increased gradually with the increase of site quality grade.(4)Comprehensive analysis by using correlation and relative importance,vertical structure,horizontal structure,age structure,stand growth,top quality competition of stands,site updates,and forest age is the key to influence the Pinus Massoniana forest biomass and productivity index,but the eight indexes of forest biomass and productivity contribution has obvious difference.In conclusion,this study explore the implementation based on forest resources subcompartment data of Pinus Massoniana plantation site quality comprehensive evaluation of forestland and non forest land system reveals the site and forest age influence on growth of Pinus Massoniana plantation,further clarify the mechanism of Pinus Massoniana plantation productivity,as the research area of Pinus Massoniana plantation to mass transfer efficiency and provides the theory basis for sustainable management.