14~ Cmeasurement of forest soils in Dinghushan Biosphere Reserve

Organic carbon in forest soils of Qingyunsi and Wukesong profiles can be divided into fast and slow components. Δ14C values of these profiles decrease with increasing of depth. The Δ14C values in 30–40 cm depth interval of Wukesong profile are decreasing sharply until a very low value, showing that a strong geological environment change occurred about 1 560 years ago. The14C apparent ages of Wukesong profile show that the coniferous and broad-leaf mixed forests around Wukesong profile have been developing since 425 a BP, which is consistent with historical documents. The penetrating depths of “bomb14C” in Qingyunsi and Wukesong profiles are 10 and 20 cm, respectively.