Floristic diversity and carbon stocks in the periphery of Deng–Deng National Park, Eastern Cameroon

Abstract

Carbon is continuously being removed from the atmosphere by photosynthesis and stored in carbon pools (live, dead, and soil carbon) of forest ecosystems. However, carbon stock in dead wood and of trees with diameters at breast height (dbh) between 5 and 10 cm is often not considered in many studies carried out in the Congo Basin Forest. The relationship between tree diversity, life-forms and carbon stocks has received little attention. This study was carried out on the outskirts of Deng Deng National Park (DDNP) to determine tree diversity (dominant families, species richness and Shannon index), assess carbon stocks in the five carbon compartments (living tree, understory, fine roots, dead wood and litter) as well as to analyze the relationship between (1) carbon stocks and tree diversity; and, (2) between carbon stock and life-forms. The Shannon index of trees ≥ 10 cm dbh ranged from 2.6 in riparian forest to 4.3 in secondary forest; and for the tree between 5 and 10 cm, it ranged to 1.56 in riparian forest to 3.68 in the secondary forest. The study site housed 16 species, 7 genera and 3 families which are only found in trees of dbh between 5 and 10 cm. The average total carbon stock of the five compartments varied from 200.1 t ha−1 in forest residues to 439.1 t ha−1 in secondary forest. Dead wood carbon stock varied from 1.2 t ha−1 in riparian forests to 12.51t ha−1 in agroforests. The above ground carbon stocks for trees with diameter between 5 and 10 cm varied from 0.7 t ha−1 in young fallow fields to 5.02 t ha−1 in old secondary forests. This study reveals a low but positive correlation between species richness and total carbon stocks, as well as a significant positive relationship between life-forms and total carbon stocks. The findings highlight the need for more data concerning carbon content of dead wood, carbon of trees ≥ 5 cm < 10 cm dbh and the relationship between carbon stocks and tree diversity from other areas of the Congo Basin for a good understanding of the contribution of tropical forests to climate change mitigation.