| With the implement of Guangxi valuable tree species planning, as one of twenty development species of A fraxinifolius, its high chase straight, beautiful shape, excellent material and the advantages of rapid growth, has the very good prospects for development, so in-depth study the species to make up the gap in the understanding has important significance.This study introduce the concept of "green accounting", put the. forest into the accounting method of the national economic system to accounting research the36-year-old precious species A. fraxinifolius plantation in the middle area of Guangxi, from the plantation growth, biomass and productivity aspects stand physical volume of accounting, and then based on the forest, forest land, forest ecological service main function conversion value, forming a complete set of accounting system of A. fraxinifolius plantation, and provide a theoretical basis for the other precious tree.This research through set up the standard to obtain the average tree in A. fraxinifolius plantation cultivate in1976by Guangxi weidu forest farm. The stem analysis methods, tree hierarchical harvest method, quadrat yield obtained forest, forest biomass and productivity of physical quantity, with afforestation investment value analysis, forest ecological service function of green accounting method to obtain forest, woodland and ecological service function values, and evaluation and analysis the accounting index system with ahp. The results show as the following:l,In the middle area of Guangxi, the average height, DBH and volume(peeled) of36-year-old A. fraxinifolius plantation were28.73m,37.37cm,1.5128m3. tree height, DBH, volume growth was positively associated with age relationship. At the growth forcast moldel between measurin factor and the age, the Korf model was superior in the growth process of the DBH, and the Schumacher model was superior to the growth process of the height and volume. The tree height annual increment growth curve show as double peaks, The average growth increment reached the highest was at16th years, the maximum value was1.04m, the peak of annual increment of DBH at4th years was1.89cm, the current annual increment and average growth curves was intersected between16-18years, which the same as tree height growth. The annual volume growth reach maximum was in34th years (0.0809m3), the average growth rate reaching the maximum was at36th years (0.0392m3), The volume growth curve and average growth curve had not yet intersect, the36-year-old A. fraxinifolius did not reach the age of quantitative maturity. Breast-height form factor shows a rapid then slow downward trend, tree height, DBH and volume of annual growth rate increased with increasing age after the first steep slow decline, the species was good for cultivate the large diameter timber.2, The individual average biomass of36-year-old A. fraxinifolius plantation was1463.87kg, the ratio of aboveground biomass to total strain was85.06%; the ratio of underground biomass to total strain wasl4.94%, The order of each organ size was:strain> bough> foudation root> bark> leaf> thick root>fine branch>dead branches> secondary root> fine root. The total biomass of the stand was814.453t per hm, of which the total arbor layer biomass was805.13t per hm, accounting for98.86%of the total stand biomass; understory vegetation biomass was9.32t per hm, The ranking of biomass of each level was:tree layer> shrub layer> litter layer> herb layer, aboveground biomass was684.85t per hm2, representing stand84.09%; the underground biomass was120.27t per hm2,as14.77%in total forest. The net productivity of A. fraxinifolius plantation was38.21t per hm2per year, which accounted for91.6%of the arbor layer stands; annual net productivity of each organ of size of the order was:stem> leaf> Branch> root> litter; tree layer productivity were11.59times,184.20times to shrub layer and herb layer. Biomass estimates show highest correlation with factor of tree measuring D2H, it can estimating the biomass by age class or diameter class.3,The forest value of36-year-old A. fraxinifolius plantation was889409.8yuan per hm, and the forest land valus was8094yuan per hm. Analysis of silvicultural static index showed that, total profits reached683642.2yuan per hm2, the profit rate of investment was9.23%, the investment profit rate was10.25%, investment recovery period was35.02years; dynamic economic indicators of financial net present value was3972yuan, the financial internal rate of return was13.22%, the static and dynamic economic indicators all reflected the high profit ability of36-year-old A. fraxinifolius plantation afforestation project. The sensitivity analysis of afforestation project showed that the most obvious effect was timber price variation, wood breakeven price was221.8yuan per stere, the synthetic material was218.4yuan per ton, All indicators showed that A. fraxinifolius silvicultural investment have a high market anti-risk ability, this species had a good investment potential.4, The ecosystem service function value of36-year-old A. fraxinifolius plantation was89067yuan per hm2per year. The order of index value was:carbon fixation and oxygen release value>water conservation value> air purify value> biodiversity conservation value> soil conservation value; the specific value respectively for47664yuan per hm2per year,29127yuan per hm2per year,6180yuan per hm2per year,5000yuan per hm2per year,1096yuan per hm2per year, Accounted for the total forest ecosystem service function value of53.51%,32.70,6.94%,5.61%,1.23%. The ecosystem service function value of36-year-old A. fraxinifolius plantation was4.7times of the value of the forest (the annual profit was18990yuan per hm2), and84.5times of forest land (8094yuan per hm2), the ecological service function value was higher than the forest and forest land value.5, The accounting system evaluation of36-year-old A. fraxinifolius plantation showed that the sort of3target layer according to contribution was forest resource economic value>ecological service function value>timber resource, and weight values were0.558,0.320,0.122; forest value, fixing carbon and releasing oxygen value were the top two in the13index system. |
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