As global climate change continues to accelerate,biological carbon storage,which plays an important ecological role in forest ecosystems,have a very significant effect on carbon emissions and carbon sinks and also play an important role in carbon cycle.Forest ecosystems,as a principal component of terrestrial ecosystems,are the world's largest carbon(C)pool and C sink.The amount of C storage in vegetation plays an important role in global C cycle and C balance.Scientifically and effectively measuring biological C storage provides important data needed for understanding the significance of forest biomass in the C cycle as well as for understanding climate change.This study analyzed biological C storage in typical forest types in the Daxing'anling Mountains in Heilongjiang Province, China,using forest inventory data and geographic information system technology.Five typical forest types in the Daxing'anling Mountains were studied using various age groups and different forest components(trees,shrubs, herbs and litter),specifically Larix gmelinii,Betula platyphylla,Pinus sylvestris var.mongolica,Quercus mongolica,and Populus davidiana forests.For each forest type,tree,understory shrub,herb,and litter layers were surveyed to determine and measure biomass per unit area,C biomass,and C forest stocks.At the stand level, age groups were classified so that estimates of forest biomass and forest C stocks in the study area could be calculated.The biomasses in different age groups of the five typical forest types in the Daxing'anling Mountains including young forest,middle-aged forest,near mature forest,and mature forest were analyzed:.Biomass per unit area of Larix gmelinii forests for these four age groups was 31.00 t/hm~2,101.29 t/hm~2,188.46 t/hm~2,and 215.23 t/hm~2,respectively.Similarly,the same four age groups of Betula platyphyllaforests held 33.13 t/hm~2,65.64 t/hm~2,88.67 t/hm~2,and 136.38 t/hm~2 of biomass per unit area;the four age groups of Pinus sylvestris var. mongolicaforests had 61.22 t/hm~2,120.30 t/hm~2,179.10 t/hm~2,and 229.43 t/hm~2 of biomass per unit area;the four age groups of Quercus mongolicaforests had 23.89 t/hm~2,25.00 t/hm~2,70.70 t/hm~2,and 126.20 t/hm~2 of biomass per unit area;and,the four age groups of Populus davidianaforests had 47.28 t/hm~2,61.71 t/hm~2,91.16 t/hm~2,and 135.53 t/hm~2 of biomass per unit area,respectively.Our study determined that biological C storage of the five typical forest types in different age groups varied widely in the Daxing'anling Mountains.C storage per unit area for young forest,middle-aged forest,near mature forest,and mature forest listed in respective order,for each forest type are as follows:15.20 t/hm~2,50.96 t/hm~2,95.80 t/hm~2,and 109.33 t/hm~2 for Larix gmelinii forests;15.36 t/hm~2,30.67 t/hm~2,41.62 t/hm~2,and 64.35 t/hm~2 for Betula platyphyllaforests;29.89 t/hm~2, 59.92 t/hm~2,90.01 t/hm~2,and 117.08 t/hm~2 for Pinus sylvestris var.mongolicaforests;11.17 t/hm~2,11.90 t/ hm~2,34.94 t/hm~2,and 59.49 t/hm~2 for Quercus mongolica forests;and,21.81 t/hm~2,28.58 t/hm~2,42.84 t/ hm~2,and 64.39 t/hm~2 for Populus davidiana forests.These results show that biological C stocks in the Daxing' anling Mountains play an important role in the C cycle and regional C balance.Different age groups in five typical forest types serve as forest C stocks based on forest biological age with the C stock increasing with forest growth and aging.Nevertheless,the type of forest C sink function varies in different forest types,although the same types of large differences were observed in biological C forest reserves in stands of different ages among the five forest types. Because most of the growth in the five major forest types occurs in young and middle-aged forest,forests at these ages have a great potential to provide C storage in forest vegetation.