| Trenched plots were set up in 2010 in a secondary forest in subtropical China, in order to investigate the seasonal variations of soil respiration (Rs) and heterotrophic respiration (Rh). Autotrophic respiration (Ra) was estimated to be the difference between Rs and Rh. Soil temperature and moisture were simultaneously measured during respiration measurements. Results indicated that Rs and Rh showed the similar seasonal variations. Seasonal mean rates for Rs, Rh and Ra were 3.42, 2.36 and 1.06 μmol·(m2 ·s)-1, respectively. Regression analysis indicated that Rh increased with the increase of Rs; an natural logistic equation could be employed to explained the relationship between Rh (y) and Rs (x). Approximately 90.5% (R2 =0.905) variations in Rh could be explained by the equation. Apparent exponential relationships of Rh and Ra with soil temperature existed, but differed from each other and from the relationship for Rs. The exponential equations explained about 78.4%, 76.4% and 65.6% variations in Rs, Rh and Ra, respectively, with the P values less than 0.01. The Q10 values for Rs, Rh and Ra were 1.97, 1.76 and 3.31, respectively. It was indicated that, seasonally, Rh and Ra represented 69% and 31% of Rs. Ra showed significantly higher temperature sensitivity than Rh. |
