人类活动影响下淡水沼泽湿地温室气体排放变化

利用静态箱/气相色谱法,研究了三江平原淡水沼泽湿地及垦殖农业利用下CO2、CH4、N2O排放变化。不同类型湿地生长季土壤呼吸速率以季节性积水的小叶章草甸最大,湿地垦殖后土壤呼吸速率明显增大。不同类型沼泽湿地CH4排放在时空两个方面都有明显的变化,与土壤水分条件、植物群落类型和生长状况有密切关系。沼泽湿地及垦殖后农田土壤在植物生长季都为N2O的源,常年积水沼泽湿地在植物生长季N2O排放通量值较小,而土壤水分常年处于非饱和的草甸灌丛土壤N2O排放相对较高,垦殖后农田土壤N2O排放通量最大,沼泽湿地土壤N2O排放通量与土壤温度呈正相关关系,而垦殖后农田土壤不显著。

Character of the Greenhouse Gas Emission in the Freshwater Mire under Human Activities

The laws of CO_2,CH_4,N_2O emission were studied in freshwater mire in the Sanjiang Plain with the aid of static chamber techniques.During the growing season,in seasonal flooded mire wetlands,Calamagrostis angustifolia shows the strongest soil respiration,however,in perennial flooded mire, Carex lasiocarpa shows the weakest soil respiration;and after the mire wetlands cultivation,soil respiration increase greatly for the influence of soil temperature.The CH_4 emission from different mire wetlands varied greatly in temporal and spatial scales,after the mire wetlands cultivation,CH_4 emission decreases significantly,which maybe tightly related to the soil hydrological and thermal condition,plant community and growing situation.Farmland soil always is the source for N_2O during growing season in the Sanjiang Plain.Weak N_2O emission was observed in perennial flooded mire wetland in growing season,but it is strong from seasonal flooded meadow for its water-saturated soil condition lasting a long term,and highest in farmland soil.Generally,the increasing trend of N_2O emission occurs along with decreasing of soil moisture.The N_2O emission from mire wetlands soil shows significant relation with soil temperature,but insignificant from farmland.