长白山亚高山针叶林沼泽湿地碳源/汇沿水分环境梯度变化规律OA北大核心CHSSCDCSTPCD

The high latitude and altitude areas are sensitive to climate change,and the feedback relationship between the wetland carbon cycle and climate in these areas has attracted much attention.This article aimed to explore whether the carbon source/sink function of swamp wetlands has been transformed under the background of global warming in the high altitude area.The carbon emissions(CO2 and CH4)of soil heterotrophic respiration,annual net carbon sequestration of vegetation,and related environmental factors(e.g.,temperature,water level,and soil organic carbon)were measured over one year by the static chamber gas chromatography and the relative growth equation method in five kinds of natural swamps(Carex schmidtii marsh-C,Shrub Swamp-G,Larix olgensis-Sphagnum magellanicum swamp-LN,Larix olgensis-moss swamp-LX,and Larix olgensis-Carex schmidtii swamp-LT)distributed along the water environment gradient in the high altitude area of Changbai Mountain.According to the net carbon balance of the ecosystem,the carbon source/sink effect of each swamp type was quantified,and the change law and formation mechanism were revealed along the water environment gradient.The results showed that:(1)the annual average emission fluxes of CO2 from five swamps((97.68±8.64)—(291.01±18.31)mg m-2 h-1)increased by the stepped type along the water environment gradient(LT and LX were the highest in the upper habitat section of the environmental gradient,LN and G were in the middle while C was the lowest);(2)The annual average fluxes of CH4((-0.051±0.003)—(0.087±0.001)mg m-2 h-1)from C and G showed CH4 emission sources at the lower moisture gradient;while three coniferous swamps showed CH4 absorption sink at the upper habitat;(3)The fluxes of CO2 emission from the five kinds of swamps were promoted by 5 or 10 cm soil temperature(C and G was inhibited by soil organic carbon or water level);the fluxes of CH4 emission from C and G were mainly promoted by 10 cm soil temperature or 10 cm soil temperature and water level,while the fluxes of CH4 absorption from the three forested wetlands were mainly promoted by the 0 or 5 cm soil temperature;(4)The annual net carbon sequestration of vegetation((1.22±0.29)—(3.14±0.36)t C hm-2 a-1)increased along the water environment gradient;(5)The five swamps all showed carbon sources((-3.84±0.20)—(-1.12±0.45)t C hm-2 a-1)and climate warming effects(GWP was(4.31±1.65)—(13.96±0.72)t CO2 hm-2 a-1),and they all increased along the water environment gradient(LT and LX were the highest in the upper habitat section of the environmental gradient,LN and G were in the middle while C was the lowest).Our results suggested that under the background of global climate warming,marsh,shrub swamp and forested wetland all acted as carbon sources and their intensity of sources increased sequentially in the high altitude area of Changbai Mountain.They had positive feedback effects on climate change,and their formation mechanism is that the soil carbon emission process wasstronger than the vegetation carbon sequestration process.It provides an important reference for the management of carbon sources/sinks in wetlands at high altitudes.