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

高纬度和高海拔区为气候变化敏感区，该区域湿地碳循环与气候反馈关系倍受关注。为探究在全球变暖背景下高海拔区沼泽湿地碳源/汇功能是否发生了转化，以长白山高海拔区沿水分环境梯度分布的5种沼泽类型(草丛沼泽-C、灌丛沼泽-G、落叶松泥炭藓沼泽-LN、落叶松藓类沼泽-LX、落叶松苔草沼泽-LT)为对象，采用静态箱-气相色谱法和相对生长方程法，同步测定各沼泽类型全年尺度上的土壤异养呼吸碳排放量(CO₂和CH₄)、植被年净固碳量及相关环境因子(温度、水位和土壤有机碳等),并依据生态系统净碳收支平衡，量化各沼泽类型的碳源/汇作用，揭示其沿水分环境梯度变化规律及形成机制。结果表明：(1)5种沼泽类型土壤CO₂年均通量((97.68±8.64)—(291.01±18.31)mg m^-2 h^-1)沿水分环境梯度呈阶梯式递增规律性(环境梯度上部生境地段的落叶松苔草沼泽和落叶松藓类沼泽最高，中部生境地段的落叶松泥炭藓沼泽和灌丛沼泽居中，草丛沼泽最低);(2)CH₄年均通量((-0....

Variation of carbon source/sink of subalpine coniferous forested wetland along water environmental gradient in Changbai Mountains of China

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 was stronger than the vegetation carbon sequestration process. It provides an important reference for the management of carbon sources/sinks in wetlands at high altitudes.