Study On Biomass Carbon Accounting Factors Of Larix Principis-rupprechtii Plantation

Global climate change and its impacts are one of the greatest environmental problems.The rapid elevation of the atmospheric CO₂ concentration is the critical issue. To find out thecause and solution, accurately identifying the magnitude of carbon stock of forest isimportant. Due to the lack of carbon accounting factors and the greatness of uncertainty, it isurgent to develop the carbon accounting factors, especially the main tree species, in order toenhance the quality of Land-use Change and Forestry sector of National Greenhouse GasInventory and the accuracy of the carbon sequestration potential of the afforestation andreforestation activities.Based on the IPCC documents as the main basis, the paper first summarized the biomasscarbon accounting methodology and progress, collected the literature data on the Larix forest,then determined the key one of Larix species to further research, and last analyzed the wholeLarix species comprehensively. The content of the paper includes: Biomass equations(Biomass allometric equation, Biomass conversion and expansion equation), Biomass factors(Biomass conversion and expansion factor (BCEF), Biomass expansion factor (BEF), Root:shoot ratio (R), Community biomass expansion factor (CBEF), Basic wood density (WD))and Carbon fraction (CF). Main conclusions are following:â‘ Through literature data on Larix forests, we found there are significant differencesbetween the biomass equations, and between the most of biomass factors (i.e. BCEF, BEFand CBEF) of different stand origins (p＜0.05), but R is the exceptional one of Biomassfactors (p＞0.05). There are no significant differences between three accounting factor (i.e.BCEF, BEF and R) among L. principis-rupprechtii, L. kaempferi, L. gmelini, and L. olgensis.Considering the uncertainty of accounting factors of L. principis-rupprechtii, L.principis-rupprechtii was established as the key specie to research more, and its natureseemed to be particularly important for the researches of other species.â‘¡The allometric equations of Stem, Aboveground and Underground biomass of L.principis-rupprechtii were better than the ones of branch and aboveground biomass. Andamong the equation forms of biomass conversion and expansion functions, the hyperbolic curve model was chosen to describe Stem and Aboveground biomass in relations to Standvolume, and power curve model to describe the relation of Underground biomass and Standvolume.â‘¢Among the influences of ecological factors to Biomass factors, the altitude factoraffects the BEF and WD; Slope direction, gradient and soil thickness does affect the Biomassfactors; Soil types affect BEF; Human disturbance affects BCEF and BEF, but the influenceof human disturbance to R deserves to be further studies.â‘£Mean BCEF of L. principis-rupprechtii is 0.7970 Mg·m^-3(n=87, SD=0.2691), andMean BEF is 1.6111 (n=87, SD=0.5190). The BCEF and BEF decreased exponentially andtended to a constant with the increase of Stand age (A), Diameter at breast height (DBH),Stand volume (V), Stand basal area (SBA) and Mean annual volume increment (MAVI), andshowed the anti-J shape. Moreover, D had no significant correlation to BCEF and BEF(p＞0.05).⑤Based on literature data and field data, there is significant difference between meanvalues ofR (p＜0.05), but R had no significant correlation to A, DBH, V, D, SBA and MAVI.Therefore, R is a quite stable accounting factor.â‘¥Mean CBEF of L. principis-rupprechtii is 1.1381 (n=50, SD=0.1517). With theincrease of A, DBH, V, SBA and MAVI, CBEF decreased and tended to a constant. Moreover,D had no significant correlation to CBEF (p＞0.05).⑦Mean WD of L. principis-rupprechtii is 0.4355 Mg·m^-3(n=57, SD=0.0382), but thereare significant differences of WD-values in different altitude regions. With the increase of A,WD-value in the same position increases, but decrease gradually along the tree.⑧Mean CF of L. principis-rupprechtii is 50.46 (n=9, SD=0.36) %, CF-value ofaboveground part (50.80 (n=9, SD=0.51) %) is greater than underground part (49.96 (n=9,SD=0.35)%)(p＜0.05). Mean CF of shrub is 48.16(n=6, SD=0.77)%, herbage is 40.48(n=6,SD=2.98)%, and litter is 39.47(n=6, SD=3.48)%.⑨All data was divided into two populations, i.e.L, principis-rupprechtii and other L.species. There were no significant differences in BCEFs and CBEFs of two populations(p＞0.05), but significant differences in BEFs and Rs(p＜0.05). Therefore, BCEF and CBEFcan transcend the differences between species, and the values of them were 0.7844 Mg·m^-3 (n=114. SD=0.2884) and 1.1217(n=68, SD=0.1705), respectively. To satisfy the need offuture, the relationships of BCEF and CBEF to A and V were set up, and the values of BCEFand CBEF were given based on the Age class and Stand volume. In the relative scarcity ofdata or the unknown differences between the species, the ideal choice is BCEF, R and CBEF.In conclusion, firstly according to stand origins, biomass allometric equation, biomassconversion and expansion function, and the values of biomass factors were done, and then forthe factual need, values of biomass factors were computed in different tree species orecological factors. However, data on large-poles or mature forests is relatively less, Changelaws of BEF in different soil types and intensity of human disturbance, the reason of R-valuedifference in literature data and field data, relationship between WD and R, and so on, all ofthese required the more field experiments to verify the function forms and analyze the reasonof differences.