Analysis On Growth Characteristics And Carbon Collecting Volume Of Tending Thinning At Different Ages’ Plantations

With years of development,China has made great progress in various aspects of society such as economy and culture.Natural forests already can’t meet the development demands of China,and therefore it is necessary to develop plantation to make up for the lack of natural forests.Tending thinning is the main technical means to promote plantation growth.However,it is necessary to further study and describe the problem:What kind of plantation is best in tending thinning activities,and how much growth and benefit can be achieved?This paper is based on the monitoring project of forest tending subsidy in Hunan Province.According to the distribution and proportion of plantation in Hunan,this paper selected the Chinese fir plantation,Pinus massoniana plantation and broad-leaf plantation as the research object.Through the establishment of different age of the tending species and control plots,the Chinese fir plantation can be 6 years,8 years,10 years,13 years,14 years,15 years and 16 years;Pinus massoniana plantation can be 6 years,8 years,10 years and 13 years;the broad-leaf plantation can be 3 years,6 years,13 years and 14 years.The plantation can be roughly divided into young age(1-10 years)and intermediate age(10-20 years).All samples were conducted twice,and the interval between the two surveys was four years.The author investigated all the changes of growth characteristics such as the DBH of samples and the height of trees,the economic benefits as volume and other economic benefits,and the changes of the ecological benefits such as biomass and carbon sink.Through the investigation,it was found that tending thinning activities promoted the growth of plantation,but different effects happened to different age groups.The effect of tending thinning on the economic and ecological benefits of plantation in some age groups was promoted.Tending thinning has a positive effect on the economic and ecological benefits of plantation in some age groups,and the effect on the economic and ecological benefits of other age groups has been reduced.The specific conclusions are as follows:(1)Effects of Tending Thinning on Growth Characteristics of Plantations in Different Age GroupsTending thinning can increase the height and DBH growth of Chinese fir trees,Pinus massoniana and broad-leaf plantations.The average DBH growth of the tending samples was 2.1 cm,1.35 cm and 1.24 cm higher than that of the control plots.The average tree height growth of the plot was higher than that of the control plot,respectively,0.75m,0.65m and 0.4m.The growth of DBH and height of Chinese fir,Pinus massoniana and broad-leaf plantation in the middle age group was higher than that in the young plantation.Therefore,the facilitation of the height and DBH of Chinese fir,Pinus massoniana and broad-leaf plantation is mainly reflected in the middle age group.(2)Effects of Tending Thinning on The Ecological Benefit of Plantation in Different Age GroupsTending thinning played a role in promoting the growth of biomass and carbon sinks in the young Chinese fir plantation,while the growth of biomass and carbon sinks in the middle-aged Chinese fir plantation did not significantly promote the growth.For the Pinus massoniana plantation,the effect of tending thinning on the growth of biomass and carbon sink of Pinus massoniana plantation was not obvious,and the promotion of biomass and carbon sink in the middle age group was obvious.For the broad-leaf plantation,tending thinning had no obvious effect on the growth of biomass and carbon sequestration of the broad-leaf plantation in the young age group,and the subtractive effect of the broad-leaf plantation in the middle-aged group was increased.(3)Effects of Tending Thinning on The Economic Benefit of Plantation in Different Age GroupsTending thinning played an important role in the growth of young Chinese fir plantation,while the growth of Chinese fir plantation in the middle age group was reduced.Tending thinning on the young age group of Pinus massoniana plantation has no significant effect on it,while the middle age of Pinus massoniana plantation has played a catalytic role.For the broad-leaf plantation,tending thinning played a role in promoting the growth of broad-leaf plantation in the young age group,while the growth of the broad-leaf in the middle-aged group was increased.