Quantitative Analysis Of Impact Factors On Carbon Cycle Of Tahe Forest Based On InTEC Model

As the main body of terrestrial ecosystem,forest ecosystem plays an important role in maintaining global carbon balance.The temporal and spatial changes of carbon cycle are affected by meteorological changes（atmospheric temperature,precipitation,etc.）,atmospheric composition changes（CO₂ concentration,and nitrogen deposition）and forest disturbance.However,the key factor affecting forest NPP change is still unclear.In order to explore this issue,based on the comprehensive consideration of the disturbance and non-disturbance factors of InTEC model,the dynamic distribution of carbon cycle in Tahe forest from 1961 to 2015 was simulated by InTEC model.Nine scenarios were designed to simulate and analyze the quantitative contribution of different impact factors and to explore the main influencing factors of the dynamic changes of carbon cycle in Tahe forest during the simulation period.The results showed that:1)From 1961 to 2015,the NPP of Tahe forest increased by 17.99%.The average contribution of disturbance factors was 25 gC·m-2·a^-1,and the relative contribution rate was 46%,which was the most critical factor that led to the increasing NPP of Tahe forest during the simulation period.It determined the change trend of NPP of Tahe forest.Followed by precipitation,and the relative average contribution rate was-30%.The relative average contribution rate of CO₂ was 20%.Relative average contribution rates of temperature and nitrogen deposition were 3%and 1%,respectively.2)The annual fluctuation of NBP in Tahe forest was obvious,and the whole was a carbon sink.The annual average value was more than 115 gC·m-2·a^-1.Temperature was the most critical factor limiting the increasing of NBP in Tahe forest during 1961-2015,and its relative contribution rate was-41%.The disturbance factors and CO₂ were in the sub-critical and re-critical positions with the relative contribution rates of 26%and 24%,respectively.The relative contribution rates of precipitation and nitrogen deposition were-8%and 1%respectively.3)The most critical and sub-critical factors of NPP change in Tahe forest in the 1960s and 1980s were disturbance factors and precipitation.In the 1990s,disturbance factors remained the most critical factor for NPP increasing in Tahe forest,and CO₂ became the sub-key factor for NPP increasing in Tahe forest.After 2000,CO₂ became the most critical factor for NPP increasing in Tahe forest,while disturbance factors and precipitation became the second key factors in the two decades,respectively.The contribution rate has increased year by year,and the contribution of temperature exceeds that of precipitation after 2010.4)In the 1960s,temperature was the most critical factor for NBP change in Tahe forest.followed by disturbance.In the 1970s,disturbance was the most critical factor for NBP change in Tahe forest,followed by temperature.After the 1980s,the increasing of temperature was the dominant factor limiting the increasing of NBP in Tahe forest,and the contribution rate of CO₂ was only second to temperature,which played a significant role in promoting the increasing of NBP in Tahe forest.