Effects of thinning and tree enrichment on carbon stocks and tree species diversity in a secondary semi-evergreen tropical forest in Yucatan Peninsula

Management of secondary forest can contribute to climate change mitigation through carbon storage. In the Yucatan Peninsula, forest owners practise thinning and tree enrichment with commercial species in secondary forest, with the aim of halting deforestation and raising household income. This field study assessed the effects of thinning (60% removal) and tree species enrichment in 15 to 17-year-old secondary forests in Calakmul, Yucatan Peninsula, on carbon stocks (live biomass, dead biomass and soil organic carbon (SOC)), tree species diversity and abundance and the ability of tree species to store carbon. The treatments were two thinnings (T 2 ), three thinnings (T 3 ), two thinnings plus enrichment with pepper ( Pimenta dioica ) (T 2 P), no thinning and enrichment with cedar ( Cedrela odorata ) and mahogany ( Swietenia macrophylla ) (T 0 CM) and, natural secondary forest (NSF). There were no significant differences in total carbon stocks (live biomass C + dead biomass C + SOC) between treatments, but T 2 P had significantly less live biomass C than T 2 , T 3 and NSF. There were also no significant differences in tree species diversity and richness between treatments, but T 0 CM differed from T 2 , T 3 and NSF in terms of species abundance. In the present study some tree species with high potential to store carbon were identified. Although no increment in carbon stocks were identified at the time of the carbon stock assessment (10–12 years after thinning) with 60% removal of vegetation compared to NSF, the nursed and introduced tree species give extra benefits to landowners, with no detrimental effects on forest diversity.