Carbon sequestration in soils of rehabilitated plantations on severely eroded lands in tropical China

There existed hundred squared kilometers of severely eroded lands along the south coast of China. Beginning in 1950s’, a rehabilitation experiment was implemented. Now various plantations have been successfully established. Recently, we evaluated carbon sequestration in soils of the rehabilitated plantations. Barren land (the control) had a very low level of carbon content without a marked change for last 50 yrs (2.8g/kg). Eucalyptus plantation with litter removed by villagers had much lower carbon content (6.1g/kg) than protested eucalyptus (14.1 g/kg). Growing for more than 30yrs, 3 mixed broadleaf plantations had soil carbon content between 16.0g/kg and 17.1g/kg, which was still lower than a nearby natural forest (21.7g/kg). Litter mass on the land was not significantly correlated with carbon content of soils. Similar to the control, unprotected eucalyptus had low level of carbon content nearly unchanged across depth from 0cm to 100cm. At depth lower than 50cm, 2 mixed broadleaf plantations had low carbon content similar to unprotected eucalyptus. However, another mixed broadleaf plantation and the natural forest had much higher carbon content than the others. The plantation with high carbon content in deep soil was dominated by Litsea rotundifolia Hemsl, Symplocos chunii Merr., Litsea glutinosa, Psychotria rubra (Lour.) Poir., Cinnamomum burmanni (Nees) Bl., Aporusa dioica Muell. This fact suggested some plantations could sequestrate much more carbon in deep soil with relatively short time (30yrs) than the others. The result also indicated that human interfere (litter removal) could largely reduced carbon sequestration in soil of eucalyptus plantation.