The Observation Of Soil Respiration And CO₂ Fluxes Of Evergreen And Deciduous Broad-leaved Mixed Forest In Tianmu Mountain

From January to December in 2014 in Tianmu Mountain of Zhejiang Province,we build up subtropical evergreen and deciduous broad-leaved mixed forest observation tower,CO₂ infrared analyzer,Li-Cor 8150 open soil carbon flux measurement system.Based on these data,we analyzed the dynamics the carbon flux components in different time scales,the soil respiration daily rate,monthly dynamic of the main environmental factors which influenced the soil respiration,discussed the characteristics of daily,monthly and seasonal dynamic of the soil respiration,the relationship among the soil respiration and the main environmental factors,estimated soil carbon release.Meanwhile,we also calculated the carbon source/sink properties and strength of the ecosystem to provide scientific basis for forest ecosystem carbon recycle in subtropical regions of our country.The major conclusions are summarized as follows:1.The daily dynamic of soil respiration in the evergreen and deciduous broad-leaved mixed forest of Tianmu Mountain presented a single peak curve.The highest value of daily dynamic appeared between 12:00 and 18:00,the lowest value appeared at 0:00 or 4:00.It is showed that soil respiration rate in the day were all higher than in the night.The monthly dynamic of soil respiration rate showed a single peak curve,too.The maximum value of soil respiration rate appeared in July,the minimum value was in December.The annual average values of soil respiration rate was 1.43μmol·m^-2·s^-1.The seasonal dynamic of the soil respiration rate expressed as: summer > autumn > spring > winter.The seasonal dynamic of the soil respiration rate.The average value of soil respiration rate between summer and other 3 seasons was significantly（P<0.01）,There were not significant differences in spring,winter and autumn（P>0.05）.2.The data of soil respiration rate without the data of February（because of the heavy snow）showed high considerably exponential correlations with atmospheric temperature and soil temperature in 5cm depth（p<0.01）.Q₁₀ value（temperature sensibility index）of soil respiration was 2.72.The monthly variation of soil carbon release was obvious.The maximum value of soil carbon release appeared in July(0.79 tC·hm^-2),The annual soil carbon release in2014,was 5.00 tC·hm^-2·a^-1.3.The ecosystem had a negative monthly CO₂ flux that played role of a carbon sink except forJanuary.The monthly carbon sequestration showed a double-peak curve,and the maximum carbon sink was occurred in June,then in October.The net ecosystem exchange（NEE）at the time point of positive and negative conversion had typical seasonal characteristics.The yearly net ecosystem exchange（NEE）,ecosystem respiration（RE）were-53.9 and 8.91 tC·hm^-2·a^-1.Soil respiration was the major component of ER,accounting for 56%.RS showed high considerably exponential correlations with the mount of NEE and RE,one of them is negative correlation and another is positive correlation.