C-14 measurement of forest soils in Dinghushan Biosphere Reserve

Organic carbon in forest soils of Qingyunsi and Wukesong profiles can be di vided into fast and slow components. Delta C-14 values of these profiles de crease with increasing of depth. The Delta C-14 values in 30-40 cm depth in terval of Wukesong profile are decreasing sharply until a very low value, s howing that a strong geological environment change occurred about 1560 year s ago. The C-14 apparent ages of Wukesong profile show that the coniferous and broad-leaf mixed forests around Wukesong profile have been developing s ince 425 a BP, which is consistent with historical documents. The penetrati ng depths of "bomb C-14" in Qingyunsi and Wukesong profiles are 10 and 20 c m, respectively.