[Investigation of heterotrophic and autotrophic components of soil respiration in a secondary forest in subtropical China].

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