| The environment and development remain the main theme of the world’s concern,and the environmental problems arising from the single tree speciations are already in the front of the people of the world,and the sustainable development is more and more emphasized,so that the planted forest which takes into account the environment and the development can be popularized vigorously.Axodiaceae is a rare and rare plant unique to China,and has the advantages of wide adaptability,high growth speed,straight dry shape,good material property and high accumulation volume per unit area,and has become an excellent substitute tree for Chinese fir trees in south China.In this article,we have studied the growth of a period of 25 years’ Taiwania flousiana plantation Hilltop forestry field in nandan county,south of guangxi,by the investigation in the field and the laboratory analysis,research on the growth characteristics and biological productivity of the plantation,at the same time,the economic,social and ecological benefits are analyzed and evaluated.The main results are as follows:(1)a period of 25 years’ Taiwania flousiana plantation,Its average chest diameter,average height of the tree and the individual volume of the individual plant is up to 26.38 cm,17.8 m and 0.4677 m cubed,and the forest is stored at 434.96 m cubed/hm squared.In the early stages of the growth of the Taiwania flousiana,the growth rate is slower,and the average growth of the tree was at the maximum of 11a,and the average growth of the thoracic diameter reached the maximum at 11a,and then gradually decreased with the increase of tree-age.The growth of the volume of the material increased gradually with the increasing of thetree-age,it was found that one fast-growing period when the fifth year,the annual growth rate reached a peak of 0.0275 m3 in 17a,after that,the growth of the material was still in the period of rapid growth,not reaching the mature age。(2)25a taiwania flousiana plantation plant biomass is 223.92 kg/strains,forest biomass is 223.23 t/hm2,the biomass of arborous layer was 208.25 t/hm2,which is 93.29%;The biomass of shrub layer was 4.84 t/hm2,accounting for 2.17%;The litter biomass was 7.56 t/hm2,accounting for 3.39%.In the proportion of biomass distribution of each organ in the tree layer,the maximum economic biomass(dry material)was 126.66 t/hm2;The secondth is the branch,the roots and the leaves,which are 36.12 t/hm2,26.16 t/hm2 and the 11.25 t/hm2;The bark is minimal,it’s only 8.05 t/hm2。The net productivity is 8.32 t/(hm2·a),which is the largest of the boles,5.06 t/(hm2·a)of 25 a taiwania flousiana plantation,the bark is the smallest,just 0.32 t/(hm2·a)。(3)The combined efficiency of the artificial forest for 25a taiwania flousiana plantation is 514819.78 元/hm2,of which the economic benefit is 345391 元/hm2,the social benefit is 53865 元/hm2,the ecological benefit is 1156873 元/hm2。Based on the economic efficiency of the forests of 25a taiwania flousiana plantation the in northwest guangxi,it’s a net profit of 345391,an annual investment margin of 21.67%,and an internal rate of 17%,which means that the investment project is in a profitable state,has a strong competitiveness,the ability to take risks,which has a higher profit margin.Above all,taiwania flousiana in northwest guangxi has stronger ecological adaptability,forest growth and forest stand volume are higher,with 25a as its rotation period,it can obtain good economic benefit,social benefit and ecological benefit,and has good popularization plan and development prospect. |
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