ObjectiveBoth stand age and climate change are crucial factors influencing forest volume dynamics, and it is important to investigate their effects on forest volume on a regional scale.
MethodBased on an ecological process model (3-PG), data from a forest resource planning and design survey and three future climate scenarios (BS, RCP4.5, and RCP8.5), this study quantified the effects of stand age and climate change on the volume growth of Pinus massoniana forests in the Three Gorges Reservoir Area (TGRA) of central China.
ResultStand age was predicted to increase the annual average volume of the Pinus massoniana forests by 2.60 × 106 m3/year or 2.60 m3/(ha·year) in the TGRA during 2009 to 2050. While the effect of climate change was less pronounced than that of stand age, an annual volume increment of 1.70 × 105−2.00 × 105 m3/year or 0.17−0.20 m3/(ha·year) only accounted for 6.55%−7.67% of the effect of stand age. The effects of both stand age and climate change on volume growth in Pinus massoniana forests were predicted to be the strongest in the central part and the weakest in the southern part of the TGRA. The Wanzhou District was predicted to present the highest annual average increment of volume per hectare (4.54 m3/(ha·year)) owing to stand age; while Banan District, the lowest value (1.17 m3/(ha·year)). The promoting effects of climate change on volume growth were predicted to be the highest in Kaizhou District (0.40 m3/(ha·year)); the lowest in Fuling District (0.03 m3/(ha·year)).
ConclusionBoth stand age and climate change are predicted to enhance the volume growth of the Pinus massoniana forests, and their combined effects would most increase the annual average volume increment per hectare in Wanzhou and Kaizhou Districts and least in Banan District. Studies are required to focus on the growth of Pinus massoniana forests in Banan District in the future through strengthening of forest management and adjustment of the forest age structure to maintain the development of regional forest resources.