Abstract:

Aims Our objectives were to (a) explore potential applications of tree-ring analysis for evaluating biomass dynamics of different forest restoration approaches in Western Sichuan, (b) compare aboveground biomass and stem volume with differently restored forests, and (c) identify the appropriate management approaches for different management aims.
Methods We intensively surveyed three replicated plots for each restoration approach and cored and measured all living trees with diameter at breast height (DBH) ≥ 5 cm using dendroecological methods. Dynamics of aboveground biomass and stem volume were calculated by means of allometric relationships and one-way tree volume models based on continuous variation of DBH.
Important findings Forests in all three restoration approaches entered into an accelerated growth phase after 20 years, when significant differences in average DBH were observed among different forest types. Planted spruce (Picea asperata) forest (PSF) showed faster growth in mean DBH than secondary birch (Betula spp.) forest (SBF) and secondary coniferous and broad-leaved mixed forest (SMF). In the process of recovery, SMF had the highest aboveground biomass and stand volume; its biomass was significant higher than that of PSF (p < 0.05) throughout and higher than SBF after 20 years. SBF had a higher aboveground biomass compared with that for PSF during 1–25 years and a lower value after 25 years. Before 20 years, the stand volume of SBF was higher than that of PSF, but PSF had higher volume after 20 years. Before 30 years, the aboveground net primary productivity for three forest types ranked SMF>SBF>PSF. After 30 years, the order changed to SMF>PSF>SBF. Results indicated that SMF had an advantage in both biomass and stand volume accumulation among the three restoration approaches.