Effect of selective logging on soil organic carbon dynamics in tropical forests in central and western Africa

Changes in soil organic carbon (SOC) as a consequence of selective logging activities are often neglected in tropical areas, even within activities that aim to promote the permanence of forest C stocks (e.g. REDD+). In this context, we assessed the magnitude of the impact of selective logging on the SOC levels in three chronosequences in Ghana, Cameroon and Gabon. In each chronosequence, from unlogged forest to forest that was selectively logged at different times in the past, adjacent plots were investigated by sampling the soil at various depths to 1 m. Both SOC concentrations and stocks drastically decrease after selective logging in all sites. The 0-5 cm depth represents the layer with the most evident SOC decreases, particularly in the first and second decades after selective logging. The SOC loss is later stabilised, but the C levels remain lower than those of the unlogged forest 45-50 years after selective logging. In all the investigated chronosequences, the SOC levels are strongly affected by selective logging and the soils continue losing C for many years. In conclusion, SOC measurements should be used to provide precise C emission-removal estimates also for forests managed using sustainable management practices.