Carbon isotopic composition, turnover and origins of soil CO2 in a monsoon evergreen broadleaf forest in the Dinghushan Biosphere Reservoir, South China

• Published in: Chinese science bulletin 2010-08, Vol.55 (23), p.2548-2556
• Main Authors: Ding, Ping, Shen, ChengDe, Wang, Ning, Yi, WeiXi, Ding, XingFang, Fu, DongPo, Liu, KeXin, Zhao, Ping
• Format: Article
• Language: English
• Subjects: Chemistry/Food Science; Earth Sciences; Engineering; Humanities and Social Sciences; Life Sciences; multidisciplinary; Physics; Science; Science (multidisciplinary); 国土安全部; 土壤CO2; 碳同位素组成; 营业额; 阔叶林; 鼎湖山
• ISSN: 1001-6538; 1861-9541
• DOI: 10.1007/s11434-010-3072-z

Carbon isotopic compositions of soil CO2 in rainy season （July） from two natural soil profiles （DHLS ＆ DHS） in the monsoon evergreen broadleaf forest in the Dinghushan Biosphere Reservoir （DBR）, South China, are presented. Turnover and origins of soil CO2 are preliminarily discussed in this paper. Results show that the content of soil CO2 varies between 6120 and 18718 ppmv and increases with increasing depth until 75 cm, and then it declines. In DHLS, soil CO2 δ13C ranges from -24.71%o to -24.03%0, showing a significant inverse correlation （R2=0.91） with the soil CO2 content in the same layer. According to a model related to soil CO2 δ13C, the soil CO2 is mainly derived from the root respiration （〉80%） in DHLS. While in DHS, where soil CO2 δ13C ranges from -25.19%o to -22.82%0, soil CO2 is primarily originated from the decomposition of organic matter （51%-94%）, excluding the surface layer （20 cm, 90%）. Radiocarbon data suggest that the carbon in soil CO2 is modem carbon in both DHLS and DHS. Differences in 14C ages between the ＂oldest＂ and ＂youngest＂ soil CO2in DHLS and DHS are 8 months and 14 months, respectively, indicating that soil CO2 in DHLS has a faster turnover rate than that in DHS. The△14C values of soil CO2, which range between 100.0‰and 107.2‰ and between 102.5‰ and 112.1‰ in DHLS and DHS, respectively, are obviously higher than those of current atmospheric CO2 and SOC in the same layer, suggesting that soil CO2 is likely an important reservoir for Bomb-^14C in the atmosphere.