Aboveground biomass of three conifers in the Qianyanzhou plantation, Jiangxi Province, China

Regressive models of the aboveground biomass for three conifers in subtropical China—slash pine ( Pinus elliottii ), Masson pine ( P. massoniana ) and Chinese fir ( Cunninghamia lanceolata )—were established. Regression analysis of leaf biomass and total biomass of each branch against branch diameter ( d ), branch length ( L ), d 3 and d 2 L was conducted with functions of linear, power and exponent. A power law equation with a single parameter ( d ) was proved to be better than the rest for Masson pine and Chinese fir, and a linear equation with parameter ( d 3 ) is better for slash pine. The canopy biomass was derived by adopting the regression equations to all branches of each individual tree. These kinds of equations were also used to fit the relationship between total tree biomass, branch biomass, foliage biomass and tree diameter at breast height ( D ), tree height ( H ), D 3 and D 2 H , respectively. D 2 H was found to be the best parameter for estimating total biomass. However, for foliage biomass and branch biomass, both parameters and equation forms showed some differences among species. Correlations were highly significant ( P <0.001) for foliage biomass, branch biomass and total biomass, among which the equation of the total biomass was the highest. With these equations, the aboveground biomass of Masson pine forest, slash pine forest and Chinese fir forest were estimated, in addition to the allocation of aboveground biomass. The above-ground biomass of Masson pine forest, slash pine forest and Chinese fir forest was 83.6, 72.1 and 59 t/hm 2 respectively, and the stem biomass was more than the foliage biomass and the branch biomass. The underground biomass of these three forests which estimated with others’ research were 10.44, 9.42 and 11.48 t/hm 2 , and the amount of carbon-fixed were 47.94, 45.14 and 37.52 t/hm 2 , respectively.