Potential of biological invasion for carbon sequestration in a protected area : the case of the Limbe Botanic Garden (LBG) forest, Cameroon

Abstract

The Limbe Botanical Garden (LBG) is a relict urban forest located in the heart of the city of Limbe. This forest has many ecological, economic, social and tourist functions and is the green lung of the city of Limbé. Unfortunately, this forest has always been threatened by various anthropic pressures and more recently by invasive exotic species. These threats make us fear the progressive disappearance of this massif, which would be a threat to the plant and animal populations, the riparian communities and the ecosystem services such as carbon regulation. The general objective of our study is to assess the validity of the hypothesis of increased carbon sequestration of invasive species compared to native species. For the floristic inventory, twenty 100 m2 (10 m x 10 m) plots were set up in this LBG urban forest. We recorded information such as the number of adult and juvenile individuals and the diameter of trees greater than or equal to 10 cm. The inventory recorded 349 plant species. The most frequent species is Cyathea camerooniana with 92.3% presence. Cedrela odorata has a frequency of occurrence of 76.9% in this urban forest and a frequency of 60% in the LBG. This taxon has a very high above-ground biomass (187.4 tC/ha) and therefore the highest carbon storage capacity (93.7 tC/ha). It is followed by Diospyros crassifolia and Dialium pachyphyllum, both native species. Cedrela odorata has a positive impact on carbon sequestration and therefore contributes to the well-being of the people. However, the conclusion needs to be qualified because invasive species can influence the functioning of forests in the long term.