ObjectivesBiomass estimation is critical for carbon stock assessment under global climate change. Taibai Mountain is the main peak in the Qinling Mountains. The forest biomass distribution in Taibai Mountain would provide basis for the dynamics of forest carbon sequestration during the vegetation restoration in the Qinling Mountain.

MethodWe analyzed the differences of above-ground biomass in different habitats, sampling scales and DBH classes. The significance of difference was determined by ANOVA based on the field measurements of environmental factors and trees with DBH ≥ 1 cm in two 1.5 ha permanent plots in the primary and secondary Q. aliena var. acuteserrata forests.

ResultThe results showed that the average above-ground biomass of the primary and secondary forest plots were 279.50 and 217.81 t/ha, respectively. Significant differences were found in above-ground biomass in different habitats. In the primary forest, the above-ground biomass was larger in the habitat with low total nitrogen, while the above-ground biomass in the secondary forest was larger in habitat with lower available phosphorus. Moreover, the above-ground biomass was larger in the habitat with a higher degree of concavity in the primary forest. At the same sampling scale, the above-ground biomass in the primary forest was larger than in the secondary forest. No significant difference in the above-ground biomass was found at different sampling scales in each forest. However, in the primary forest, the average above-ground biomass showed an unimodal trend along the increase of DBH class. And the above-ground biomass was the largest at the Ⅵ DBH class. The above-ground biomass increased along the increase of the DBH class in the secondary forest. The above-ground biomass in the primary forest was higher than that in the secondary forest at the Ⅳ ~ Ⅶ DBH classes, while smaller than that in the secondary forest at the Ⅸ DBH class.

ConclusionTherefore, disturbance, habitat heterogeneity and DBH class can affect the above-ground biomass allocation in Q. aliena var. acuteserrata forests.