Search

The magnitude of soil CO2 emission varying significantly among different vegetation types for plants could alter the microclimatic environment of soil. In a Pinus tabulaeformis plantation and an adjacent Quercus aliena var. acuteserrata shrub, which are located in a dry-hot valley region of Minjiang River in the Southwest of China, the daily soil CO2 emission dynamics was measured in August 2004 and in May, July, and October 2005. The results showed that the soil CO2 emission in the oak shrub was significantly higher than the pine plantation in each measurement period. Additionally, soil organic matter, microbial biomass carbon, and the leaf litter decomposition rate in the two vegetations differed significantly from each other. The variation of soil organic matter and microbial biomass carbon partially contributed to the evident difference in soil CO2 emission. Moreover, the correlations between soil CO2 emission, soil temperature, and soil water content were evaluated in this study. The soil temperature positively controlled soil CO2 emission in the pine plantation and the oak shrub, while the soil water content negatively influenced soil CO2 emission in the two vegetation types. However, the soil temperature and soil water content played varied roles in the different vegetation types. By the means of stepwise regression, the soil temperature more significantly influenced the dynamics of soil CO2 emission for the plantation than the soil water content; oppositely, the soil water content was the more significant controlling factor for the shrub. Based on the exponent model between the soil CO2 emission and soil temperature, the Q 10 values were estimated, which was 1.7 in the pine plantation and 3.0 in the oak shrub. The former was lower than the global average level of 2.0, whereas the latter was higher than the global average level. [ABSTRACT FROM AUTHOR]