亚热带常绿阔叶林9个常见树种的生物量相对生长模型

Biomass allometric equations of nine common tree species in an evergreen broadleaved forest of subtropical China

生物量相对生长模型作为一种简便且有效的生物量估算方法,已得到广泛应用.国内偏重于针叶林或阔叶纯林的生物量相对生长模型研究,而在估算多树种阔叶林的生物量时,一般选用混合物种的生物量相对生长模型,这会导致估算结果产生较大误差.本文在亚热带常绿阔叶林典型分布区随机设置了33块样地,针对栲树、鹿角锥、钩锥、石栎、猴欢喜、虎皮楠、赤杨叶、乳源木莲和少叶黄杞9个常见的树种,构建了单物种及混合物种的生物量相对生长模型,并探讨了单物种模型及混合物种模型间估算误差的差异.结果表明:以D(胸径)和D2H(胸径的平方乘以树高)为自变量,分别构建混合物种模型,其中树枝、树叶、树根、地上和整株生物量是以D为自变量的模型为优,但树干生物量是以D2H为自变量的模型为优.将树高引入以D为自变量的单物种模型后,6个树种单物种模型的解释能力呈不同程度的下降趋势,最高下降5.6%(猴欢喜).与以D和D2H为自变量的混合物种模型相比,8个树种单物种模型的SEE(估计值的标准差)出现下降;对不同器官而言,其单物种模型的SEE不同程度地下降,最高达13.0%和20.3%(树枝).不考虑种间和模型形式间的差异,将会严重影响生物量碳库及其动态评估的准确性.因此,为提高生物量估算的准确性,应综合考虑种间和模型形式间的差异.

Biomass allometric equation （BAE） considered as a simple and reliable method in the estimation of forest biomass and carbon was used widely. In China, numerous studies focused on the BAEs for coniferous forest and pure broadleaved forest, and generalized BAEs were frequently used to estimate the biomass and carbon of mixed broadleaved forest, although they could induce large uncertainty in the estimates. In this study, we developed the species-specific and generalized BAEs using biomass measurement for 9 common broadleaved trees （ Castanopsis fargesii, C. lamontii, C. tibetana, Lithocarpus glaber, Sloanea sinensis, Daphniphyllum oldhami, Alniphyllum fortunei, Manglietia yuyuanensis, and Engelhardtiafenzlii） of subtropical evergreen broadleaved forest, and compared differences in species-specific and generalized BAEs. The results showed that D （diame- ter at breast height） was a better independent variable in estimating the biomass of branch, leaf, root, aboveground section and total tree than a combined variable （D2 H） of D and H （tree height） , but D2H was better than D in estimating stem biomass. R2（ coefficient of determination） values of BAEs for 6 species decreased when adding H as the second independent variable into D- only BAEs, where R2 value for S. sinensis decreased by 5.6%. Comnared with generalized D- and D2H-based BAEs, standard errors of estimate （SEE） of BAEs for 8 tree species decreased, and similar decreasing trend was observed for different components, where SEEs of the branch decreased by 13.0% and 20.3%. Therefore, the biomass carbon storage and its dynamic estimates were influ- enced largely by tree species and model types. In order to improve the accuracy of the estimates of biomass and carbon, we should consider the differences in tree soecies and model types.