Dynamics of soil respiration in three major plantations in mid-subtropical zone

The dynamics of the soil respiration in Phoebe bourmei plantation,Cunninghamia lanceolata(Lamb.) Hook plantation and Pinus massoniana plantation were measured by the enclosed chamber method to compare and analyze its relationship to temperature and soil water.The results showed that there was significant difference in soil respiration among the various forest types and the highest was in Phoebe bourmei plantation,followed by C.lanceolata,and the lowest was in Pinus massoniana plantation.However,the seasonal and daily pattern of soil respiration in three forest types could be expressed as a one-humped curve,and the highest values appeared in July and at 14:00,which was similar to the change of air temperature.There was an exponent correlation between the soil respiration and temperature,especially the soil temperature at 5 cm depth.The Q_(10) value of Chinese fir plantation was higher than that of the other two,which implied that the sensitivity of soil respiration to temperature in Chinese fir plantation was highest.There was a linear correlation between soil respiration and the soil water content in the upper 20 cm of soil.The relationship between soil respiration rate and the two variables of the soil temperature at 5 cm depth and the soil water content in the upper 20 cm of soil could be described with the multiple linear regression equation,which had much more predicative power than that using temperature or soil water content as single independent variables,and it was proved that the soil respiration was affected by both temperature and moisture.