亚热带常绿阔叶林8个常见树种粗根生物量

森林粗根生物量是森林生态系统生物量的重要组成部分, 然而对其研究较少, 尤其在亚热带常绿阔叶林区, 这制约了我国森林生态系统碳储量的准确评估. 基于全挖法测定了中亚热带典型常绿阔叶林区8个常见树种175棵样木的粗根生物量. 这8个树种分别为丝栗栲(Castanopsis fargesii)、苦槠栲(Castanopsis sclerophylla)、木荷(Schima superba)、马尾松(Pinus massoniana)、杉木(Cunninghamia lanceolata)、枫香(Liquidambar formosana)、檫木(Sassafras tzumu)和拟赤杨(Alniphyllum fortunei). 通过建立根系直径与根系生物量回归方程来估算断根后留在土中的根系生物量, 采用胸径和树高作为预测变量对这8个树种及所有样木混合分别构建粗根生物量异速生长方程. 结果表明, 8个树种的根系直径与根系生物量存在极显著的幂函数关系(P<0.001), 这为完整估算根生物量提供了依据. 采用胸径、树高及胸径与树高组合作为预测变量所建立的粗根生物量异速生长方程都达到了极显著水平(P<0.001), 但仅以胸径作为预测变量构建的方程较仅以树高构建的方程具有更高的拟合度. 在胸径的基础上引入树高作为预测变量并没有明显提高方程的拟合度.

The coarse root biomass of eight common tree species in subtropical evergreen forest

Though coarse root biomass is an important part in biomass of forest ecosystems, few studies were found in subtropical area. In this study, whole digging method was used to determine the biomass of coarse root (diameter>2 mm) of 175 trees of 8 species in subtropical evergreen forests. The 8 species includes Castanopsis fargesii, Castanopis sclerophylla, Schima superba, Pinus massoniana, Cunninghamia lanceolata, Liquidambar formosana, Sassafras tzumu, Alniphyllum fortunei. Also, the lost roots during excavation were corrected by developing scaling relationship between biomass of root and diameter. Then, four kinds of allometric models for each species and combined trees were fitted to link stem diameter at breast height (dbh) and height (H) to coarse root biomass. The results showed that all the scaling relationship between biomass of root and diameter of roots were significant (P<0.001), which indicated that the biomass of lost roots during digging could be estimated by the diameter of broken points. All allometric models for coarse root biomass using breast height or height as predictors were significant (P<0.001), but the dbh-coarse root biomass equations had higher R² values than the height-coarse root biomass. The results also indicate that dbh is an adequate estimator for coarse root biomass of subtropical evergreen trees. The results in this study provide important information to estimate the coarse root biomass in subtropical evergreen forests.