[Effects of soil temperature and humidity on soil respiration rate under Pinus sylvestriformis forest].

Employing root-wrenching method and LI-6400-09 soil respiration chamber, this paper measured the diurnal changes of soil respiration rate with and without roots in situ on June 17, August 5, and October 10, 2003. The seasonal changes of soil respiration were also measured from May to September, 2004. The results showed that both the total and the root-wrenched soil respiration appeared single diurnal pattern, with the peaks presented during 12:00-14:00. The diurnal fluctuation of soil respiration on August 5 was smaller than that on June 17 and October 10. There were also obvious seasonal changes in total and root-wrenched soil respiration, as well as in root respiration, which were higher from June to August but lower in May and September. The average total soil respiration, root-wrenched soil respiration, and root respiration were 3.12, 1.94 and 1.18 micromol CO2 x m(-2) s(-1), respectively, and the contribution of roots to total soil respiration ranged from 26.5% to 52.6% from May to September, 2004. There were exponential correlations between respiration rate and soil temperature, and linear correlations between respiration rate and soil humidity. The Q10 values were 2.44, 2.55 and 2.27 for total soil respiration, root-wrenched soil respiration, and root respiration, respectively. The effect of soil temperature on root-wrenched soil respiration was lager than that on total soil respiration and root respiration. Soil humidity had a larger effect on total soil respiration than on root respiration and root-wrenched soil respiration.