Phytodiversity, structure and carbon sequestered by avenue trees in the Municipality of Sèmè-Podji, Southern Benin

Abstract

The importance of plants in the urban environment is sufficiently demonstrated by their potential and the ecosystem services they generate for the environment and populations. The present work aimed at assessing the contribution of avenue trees to carbon sequestration in the municipality of Sèmè-Podji in Benin. The methodological approach used has allowed making the inventory of trees along 26 kilometers of managed roadways. The diversity and structure parameters were computed to assess the floristic potential, the diameter and height structure of the trees, then the sequestered carbon from the allometric equations established for urban environments. The results revealed 19 species grouped into 12 families and 17 genus along the explored streets. Shannon's average diversity index (3.25±0.13 bits) and Pielou's equitability (0.76±0.04) explain the dominance of a few species, among which the most representative are Terminalia catappa (33.79%), Delonix regia (12.5%), and Khaya senegalensis (9.72%). The diameter and height structures are irregular, with average of 46.75 ± 33.46 cm and 10.35 ± 5.33 m respectively. The aerial biomass for the inventoried streets is 756.16 t/ha, corresponding to a carbon stock of 378.17 t/ha, that is the equivalent of 102.09 t of CO2 per hectare. It appeared from this study that the floristic procession and the structural characteristics of the avenue trees are limited to ensure the socio-ecological functions in the municipality of Sèmè-Podji. However, this information could encourage decision-makers to take reforestation measures to increase the vegetation cover of the streets and for better management of the city's urban forestry.