| Cold temperate coniferous forests are distributed in the middle and high latitudes of the northern hemisphere,which is the second largest terrestrial biosphere in the world,and its vegetation and soil carbon storage is about 300 GT,which is equivalent to 50% of the carbon in the atmosphere,and plays an irreplaceable role in regulating the global carbon balance.China’s northern forests are mainly distributed in the Great Xing ’an Mountains area,and carbon storage accounts for more than 1/3 of China’s total forest carbon stock.The existing studies suggest that future climate change may increase forest productivity in the Great Xing’an Mountains,increasing carbon stocks in forest ecosystems.However,due to the impact of global warming,the frequency of droughts in the Great Xing ’an Mountains forest area will increase significantly,which may cause widespread death of tree species and reduce the carbon stocks of forests.Most current studies lack the response of tree species to drought and the impact of changes in drought frequency and intensity under climate change scenarios,so there is considerable uncertainty in the simulation results,which may overestimate forest carbon stocks in the region.Therefore,this project simulates the dynamic changes of forest carbon stocks in Great Xing’ an Mountains under different climate change scenarios from 2015 to 2100 by model coupling and model-field survey data fusion,to quantify the impact of climate change and drought on forest carbon stocks in Great Xing’ an Mountains.The results showed that:(1)Compared with coniferous species such as Larch and Pinus sylvestris such as Larch and Pinus sylvestris in Great Xing’ an Mountains,broad-leaved species such as aspen,birch,and birch can tolerate drought better,and have faster growth rates and stronger reproductive ability,and the climate in the study area will become more suitable for broad-leaved tree species such as aspen and birch in the future.(2)The impact of drought on tree species mortality varies with different tree species,and the drought caused by climate change in the future will increase the mortality rate of forest species in the Great Xing’ an Mountains by1.27-18.32%.At the end of the 21 st century,the mortality rate of tree species in the current climate was 6.24%,the mortality rate of tree species in most climate scenarios was higher than that of the current climate,and the mortality rate of tree species in a few climate scenarios decreased,the mortality rate of tree species in the Can ESM5＿ssp585 climate scenario was the highest,at 13.86%,and the mortality rate of tree species in the Had GEM3-GC31-LL＿ssp126 climate scenario was the lowest,at 4.21%.(3)The uncertainty of current climate models in predicting future climate change will cause differences in aboveground carbon stocks and tree species composition in Great Xing’ an Mountains forests in response to extreme drought.Different tree species also respond differently to extreme drought.The results of this study indicate that before using future climate scenarios to predict the impact of climate change on forest ecosystems,it is necessary to use some statistical analysis methods to quantify and reduce the uncertainty of climate change predictions;(4)Climate warming and increased precipitation would increase carbon stocks of boreal forests in the Great Xing’ an Mountains.The aboveground carbon of boreal forests shows an increasing trend over the 21 st century.Although drought can partially reduce carbon stocks,it cannot completely offset the increase in carbon stocks brought about by the growth of tree species.In this study,the model coupling method was used to consider the adaptation strategies of tree species to drought,and the dynamic changes of forest carbon stocks in Great Xing’an Mountains were simulated.The study reveals drought’s impacts on boreal forests’ carbon stocks under climate change scenarios,and provides a scientific basis for formulating new forest management policies. |
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