Effects of clear-cutting and slash burning on soil respiration in Chinese fir and evergreen broadleaved forests in mid-subtropical China

Soil respiration (Rs) was measured over 2 years in mature, clear-cut, and clear-cut with slash burnt stands of Cunninghamia lanceolata Lamb. (Chinese fir) (CF) and secondary evergreen broadleaved forest (BF) located in Fujian Province, southeastern China from late October 2001 to 2003. Rs was measured as CO2 evolved in situ using the soda lime absorption method. Soil temperature and moisture content at 10 cm depth were monitored in treatments of clear-cut (CC) and slash burnt (SB) and undisturbed controls. Respiration levels varied seasonally with maximum rates observed from May to July. Both, CC and SB plots showed increase in Rs for the first 3 months after treatments but for the subsequent 2 years the Rs in the CC and SB stands fell below that of controls. There were no significant difference in soil temperature among treatments in each forest, while the CC and SB treatments resulted in reduced soil moisture contents. Relationships between Rs and soil environmental variables were examined via a regression analysis. A combination of soil temperature and soil moisture content proved to be a reliable predictor of CO2 evolution in control plots, but not in CC and SB plots. We concluded that the effect of forest management on Rs is a combined result of changes in other factors rather than soil temperature and moisture. This study contributes to our understanding of how common forestry management practices might affect soil carbon sequestration, as Rs is a major component of ecosystem respiration.