Soil respiration in tropical seasonal rain forest in Xishuangbanna, SW China

Abstract

With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three treatments were applied, each with three replicates: A (bare soil), B (soil+litter), and C (soil+litter+seedling). The results showed that soil respiration varied seasonally, low from December 2003 to February 2004, and high from June to July 2004. The annual average values of CO2 efflux from soil respiration differed among the treatments at 1% level, with the rank of C (14642 mgCO 2 ·m -2 ·h -1 )>B (12807 mgCO 2 ·m -2 ·h -1 )> A (9532 mgCO 2 ·m -2 ·h -1 ). Diurnal variation in soil respiration was not apparent due to little diurnal temperate change in Xishuangbanna. There was a parabola relationship between soil respiration and soil moisture at 1% level. Soil respiration rates were higher when soil moisture ranged from 35% to 45%. There was an exponential relationship between soil respiration and soil temperature (at a depth of 5cm in mineral soil) at 1% level. The calculated Q 10 values in this study, ranging from 2.03 to 2.36, were very near to those of tropical soil reported. The CO 2 efflux in 2003 was 5.34 kgCO 2 ·m -2 ·a -1 from soil plus litter plus seedling, of them 3.48 kgCO 2 ·m -2 ·a -1 from soil (accounting for 62.5%), 1.19 kgCO 2 ·m -2 ·a -1 from litter (22.3%) and 0.67 kgCO 2 ·m -2 ·a -1 from seedling (12.5%).