Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which ...Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which is a typical temperate forest ecosystem in the mountainous areas of Beijing. Changes of CO2 concentrations in both the atmosphere (2m above canopy) and the forest canopy (2m below the top of the canopy) together with those of net photosynthesis and soil CO2 evolution were also examined, in order to find the characteristics of CO2 exchange between the different components of the temperate forest ecosystem and the atmosphere. Atmospheric CO2 averaged (323+10) and (330+1) mol mol-1 respectively in summer and autumn. During the 24-hour measurements, large differences as much as -46 and -61 mol mol-1 respectively in the atmosphere and forest were found. Net photosynthesis of the grass layer in summer was (2. 59 9+ 1.05) mol CO2 m-2 S-1, two times of that in autumn, (1.31+0.39) mol CO2 s-1 In summer, there was much more CO2 evolved from soil than in autumn, averaging (5.18+0.75) mol CO2 m-2 s-1 and (1.96 + 0.57) (mol CO2 m-2 s-1, respectively. A significant correlation was found between soil CO2 evolution and ground temperature, with F =-0.864 2+0.310 1X,r=0.7164, P<0.001 (n=117). Both the minimal atmospheric CO2 level and the maximum net photosynthesis occurred around 14:00; and an increase in atmospheric CO2 and of soil CO2 evolution during night times were also found to be remarkable.展开更多
辽宁东部山区冬季寒冷漫长,而且秋冬交替和冬春交替时期表层土壤冻融交替频繁发生,其对土壤CO2释放的影响特征还不明确。以该区典型森林类型长白落叶松(Larix olgensis Henry)人工林为研究对象,在2010—2014年期间额定非生长季冻融交替...辽宁东部山区冬季寒冷漫长,而且秋冬交替和冬春交替时期表层土壤冻融交替频繁发生,其对土壤CO2释放的影响特征还不明确。以该区典型森林类型长白落叶松(Larix olgensis Henry)人工林为研究对象,在2010—2014年期间额定非生长季冻融交替期和冻结期土壤呼吸速率(Rs)动态变化特征,并量化各时期土壤CO2释放量(F_(CO_2))的贡献。结果表明:非生长季Rs总体呈现出"U"型的变化规律,并且秋冬冻融交替期土壤呼吸速率明显大于冬春冻融交替期。非生长季年际间Rs的差异较大,年平均Rs在(0.42±0.02)^(0.72±0.04)μmol CO2·m-2·s-1。Rs与10 cm深度土壤温度(T10)和空气温度(Ta)呈现相似的动态变化规律并且具有显著的正相关关系。指数模型能够较好地拟合非生长季Rs随T10的变化规律,且2010/2011和2011/2012年的拟合效果优于2012/2013和2013/2014年,冻融交替期的拟合效果要优于冬季冻结期。2010—2014年期间4个非生长季F_(CO_2)分别为137、92、100和159 g C·m-2,年际间差异大。非生长季各时期F_(CO_2)总体上为秋冬冻融交替期最多(29.66~63.48 g C·m-2),冬春冻融交替期次之(14.57~21.48 g C·m-2),秋冬冻融交替期F_(CO_2)是冬春冻融交替期的1.68~4.36倍,二者的累计贡献率在47.69%~54.66%。冻融交替作用对于非生长季F_(CO_2)动态的贡献不可忽视,而秋冬和冬春2个冻融交替期对于F_(CO_2)的影响也存在较大差异,秋冬冻融交替期激发土壤释放CO2的能力比冬春冻融交替期更强。研究结果将有助于更好地理解我国东北地区非生长季森林土壤碳排放的规律。展开更多
基金This is a key project of National Natural Science Foundation of China.
文摘Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which is a typical temperate forest ecosystem in the mountainous areas of Beijing. Changes of CO2 concentrations in both the atmosphere (2m above canopy) and the forest canopy (2m below the top of the canopy) together with those of net photosynthesis and soil CO2 evolution were also examined, in order to find the characteristics of CO2 exchange between the different components of the temperate forest ecosystem and the atmosphere. Atmospheric CO2 averaged (323+10) and (330+1) mol mol-1 respectively in summer and autumn. During the 24-hour measurements, large differences as much as -46 and -61 mol mol-1 respectively in the atmosphere and forest were found. Net photosynthesis of the grass layer in summer was (2. 59 9+ 1.05) mol CO2 m-2 S-1, two times of that in autumn, (1.31+0.39) mol CO2 s-1 In summer, there was much more CO2 evolved from soil than in autumn, averaging (5.18+0.75) mol CO2 m-2 s-1 and (1.96 + 0.57) (mol CO2 m-2 s-1, respectively. A significant correlation was found between soil CO2 evolution and ground temperature, with F =-0.864 2+0.310 1X,r=0.7164, P<0.001 (n=117). Both the minimal atmospheric CO2 level and the maximum net photosynthesis occurred around 14:00; and an increase in atmospheric CO2 and of soil CO2 evolution during night times were also found to be remarkable.
文摘辽宁东部山区冬季寒冷漫长,而且秋冬交替和冬春交替时期表层土壤冻融交替频繁发生,其对土壤CO2释放的影响特征还不明确。以该区典型森林类型长白落叶松(Larix olgensis Henry)人工林为研究对象,在2010—2014年期间额定非生长季冻融交替期和冻结期土壤呼吸速率(Rs)动态变化特征,并量化各时期土壤CO2释放量(F_(CO_2))的贡献。结果表明:非生长季Rs总体呈现出"U"型的变化规律,并且秋冬冻融交替期土壤呼吸速率明显大于冬春冻融交替期。非生长季年际间Rs的差异较大,年平均Rs在(0.42±0.02)^(0.72±0.04)μmol CO2·m-2·s-1。Rs与10 cm深度土壤温度(T10)和空气温度(Ta)呈现相似的动态变化规律并且具有显著的正相关关系。指数模型能够较好地拟合非生长季Rs随T10的变化规律,且2010/2011和2011/2012年的拟合效果优于2012/2013和2013/2014年,冻融交替期的拟合效果要优于冬季冻结期。2010—2014年期间4个非生长季F_(CO_2)分别为137、92、100和159 g C·m-2,年际间差异大。非生长季各时期F_(CO_2)总体上为秋冬冻融交替期最多(29.66~63.48 g C·m-2),冬春冻融交替期次之(14.57~21.48 g C·m-2),秋冬冻融交替期F_(CO_2)是冬春冻融交替期的1.68~4.36倍,二者的累计贡献率在47.69%~54.66%。冻融交替作用对于非生长季F_(CO_2)动态的贡献不可忽视,而秋冬和冬春2个冻融交替期对于F_(CO_2)的影响也存在较大差异,秋冬冻融交替期激发土壤释放CO2的能力比冬春冻融交替期更强。研究结果将有助于更好地理解我国东北地区非生长季森林土壤碳排放的规律。
