To quantify the carbon source/sink function of riparian zone swamps and explore the feedback relationship with climate change, we measured the annual fluxes of soil greenhouse gas, soil carbon emission, net vegetation carbon sequestration and related environmental factors (temperature, water level, etc.) by static chamber-gas chromatography and relative growth equation methods in three kinds of forest swamps (Alnus sibirica swamp, Betula platyphylla swamp, and Larix olgensis swamp) distributed along the water reduction gradient of lowland to highland in the stream riparian zone of Changbai Mountains. The results showed that the annual fluxes of CH4(0.19-0.85 mg·m-2·h-1), CO2(60.81-228.63 mg·m-2·h-1), and N2O (-0.02-0.05 mg·m-2·h-1) showed spatial variations along the water gradient of lowland to highland, with a trend of first constant then decreasing, decreasing, and first absorption then emission, respectively. The spatial variations of annual fluxes of these greenhouse gases were controlled by water levels. The annual net carbon sequestration of vegetation (2.61-3.45 t C·hm-2·a-1) was constant along the water gradient, which was mainly promoted by nitrate nitrogen content. The carbon source/sink and global warming potential (GWP) undergo regular changes along water gradients. The A. sibirica swamp was a carbon sink (1.93 t C·hm-2·a-1), the B. platyphylla swamp was a weak carbon source (-0.18 t C·hm-2·a-1), and the L. olgensis swamp was a strong carbon source (-2.51 t C·hm-2·a-1). The spatial variation of carbon source/sink in forest swamps was jointly promoted by water level and nitrate nitrogen content. A. sibirica swamp exhibited a strong cooling effect with a strong negative feedback effect on climate change (-5.88 t CO2·hm-2·a-1). L. olgensis swamp exhibited a strong warming effect with a strong positive feedback effect (10.97 t CO2·hm-2·a-1). B. platyphylla swamp exhibited a weak warming effect, approximately neutral (2.95 t CO2·hm-2·a-1). The spatial variation of GWP in forest swamps was mainly inhibited by water level.
为量化河岸带湿地碳源/汇并探究其对气候变化的反馈关系,采用静态箱-气相色谱法和相对生长方程法,测定长白山溪流河岸带低地至高地沿水分减小梯度依次分布的3种森林沼泽(毛赤杨沼泽、白桦沼泽和落叶松沼泽)土壤温室气体年通量、土壤年净碳排放量、植被年净固碳量及相关环境因子(温度、水位等)。结果表明: 长白山溪流河岸带森林沼泽的CH4(0.19～0.85 mg·m-2·h-1)、CO2(60.81～228.63 mg·m-2·h-1)和N2O(-0.02～0.05 mg·m-2·h-1)年通量沿低地至高地水分梯度依次呈先恒定后降低、递减和先吸收后排放的空间变化规律,且这3种温室气体年通量的空间变化均受水位控制。河岸带森林沼泽的植被年净固碳量(2.61～3.45 t C·hm-2·a-1)沿水分梯度呈恒定型,主要受硝态氮含量促进。河岸带森林沼泽的碳源/汇及全球增温潜势(GWP)沿水分梯度发生了规律性的转变,其中,毛赤杨沼泽为碳汇(1.93 t C·hm-2·a-1),白桦沼泽为弱碳源(-0.18 t C·hm-2·a-1),而落叶松沼泽为强碳源(-2.51 t C·hm-2·a-1);且森林沼泽碳源/汇的空间变化受水位和硝态氮含量联合促进。毛赤杨沼泽表现为强冷却效应,与气候变化间存在较强负反馈作用(-5.88 t CO2·hm-2·a-1);落叶松沼泽表现为强增温效应,存在较强正反馈作用(10.97 t CO2·hm-2·a-1);而白桦沼泽表现为弱增温效应,近似于中性(2.95 t CO2·hm-2·a-1);且森林沼泽GWP的空间变化主要受水位抑制。.
Keywords: carbon source/sink; forested wetland; global warming potential; riparian zone; spatial variation.