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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。
In eastern Liaoning mountainous area, the winter is cold and long, and the alternate alternation of autumn and winter and the freezing and thawing of the surface soil occur frequently, and the characteristics of its impact on soil CO2 release are not clear. The Larix olgensis Henry plantation, a typical forest type in this area, was selected as the research object. During the period of 2010-2014, the dynamic characteristics of freeze-thaw cycles and frozen soil respiration rate (Rs) during the non-growing season were quantified Contribution of soil CO2 emission (F_ (CO2)) in different periods. The results showed that the Rs in the non-growing season presented a pattern of “U ”, and the soil respiration rate in the period of autumn-winter freezing-thawing alternation was obviously greater than that in winter and spring. There was a significant difference in annual Rs between non-growing season and annual mean Rs (0.42 ± 0.02) ~ (0.72 ± 0.04) μmol CO2 · m-2 · s-1. Rs and soil temperature at 10 cm depth (T10) and air temperature (Ta) showed similar dynamic changes and had a significant positive correlation. The exponential model can well fit the variation law of Rs with T10 in non-growing season, and the fitting effect in 2010/2011 and 2011-2012 is better than that in 2012/2013 and 2013/2014. Better than the winter freeze period. The F_ (CO_2) of four non-growing seasons during 2010-2014 were 137, 92, 100 and 159 g C · m-2, respectively, with significant differences between years. The F_ (CO_2) in the non-growing season was the highest in the autumn-winter freezing-thawing period (29.66 ~ 63.48 g C · m -2), followed by the winter-spring freezing-thawing period (14.57 ~ 21.48 g C m -2) The F_ (CO_2) in autumn-winter freezing and thawing alternation was 1.68 ~ 4.36 times of the winter-spring freezing and thawing alternation, and the cumulative contribution rate of both was 47.69% -54.66%. The contribution of freeze-thaw alternation to the dynamic of F_ (CO_2) during the non-growing season can not be neglected. However, the effects of autumn-winter and winter-spring alternation on F_ (CO_2) also differed greatly. The capacity of CO2 is stronger than that of winter and spring freeze-thaw cycles. The results of this study will help to better understand the laws of soil carbon emission from non-growing season forests in Northeast China.