Potential responses of different stand age classes to climate changes in the Xiaoxinganling Mountains, northeastern China

The LINKAGES model was used to make simulation predictions of future succession dynamics of different stands with various age classes in the primeval forests of Xiaoxinganling Mountains under five climate change scenarios. The five climate change scenarios were OSU, GISS, GFDL, UKMO and CGCM2. The simulation results for all simulated stands indicated that the distributions of major tree species maintained the current level, while the total biomass increased due to the gentle increase of temperature under OSU and GISS scenarios. Under the GFDL and UKMO scenarios with temperature increasing by a larger margin, the entire forest of all age classes did not adapt to the rapid changes of climate and degenerated. However, under the scenario of CGCM2, the biomass of Pinus koraiensis increased initially and decreased at the later stage. The current mixed coniferous and broadleaved Korean pine forests may gradually transform to broadleaved mixed forest dominated by Acer mono-Quercus mongolica. The comparison of different stand age classes showed that the overmature stands had stronger resistance to climate change than that of the others, while the range of climate warming was within the tolerance of P. koraiensis and its biomass level tended to be low. Young-middle aged stands could best adapt to the climate change and tended to make good use of light and nutrients, and its biomass usually reached the highest level after the composition of tree species becoming stable. On the contrary, when the range of climate warming was greater than the P. koraiensis tolerance, the resilience and recovering ability of overmature stands were both reduced, which leading to the fast degeneration of stands and apparent fluctuations of total biomass. Young-middle aged stands still had better adaptation to the climate change and the succession trends of them were most stable.