Ecological characterization and evolution of Elaeis guineensis Jacq. traditional parklands in Lower Casamance (Senegal)

Abstract

This study is a contribution to the characterization of traditional agroforestry parklands in Lower Casamance. It aims at determining the diversity of species and the tree size structure in these parklands, as well as at identifying the threats to their sustainability, in order to assist decision making on natural resource conservation. To this end, 45 plots of 50 × 50 m size were inventoried. In each plot, an exhaustive inventory of trees was performed, including species identification, height measurement and estimates of regeneration and mortality rates. Additionally, 116 stakeholders were interviewed about their management practices, the revenue they obtained from agroforestry parklands, and their opinion on the future of these parks. A total of 2739 Elaeis guineensis palm trees and 3948 trees from other species were observed in the 11.25 ha studied. Hence a relative density of 40.96 individuals of E. guineensis ha⁻¹. The 63 species belonged to 51 genus within 23 botanical families. The analysis of tree communities indicated a strong role of human management on the species composition of parklands, with cultural value trees near the villages and wood production trees further away, and with some sites having more trees with medicinal uses. The distribution of tree sizes of E. guineensis and estimates of mortality and regeneration rates indicated that the population of palm trees is ageing and regeneration is too low to compensate mortality. Based on interviews, palm production is decreasing in the area, and causes of decline identified by the farmers were salinization, drought, illegal cutting, and bush fires, i.e., both natural and anthropogenic causes. In view of the importance of these parklands for the local economy and food security, better management of E. guineensis parklands is required to ensure their sustainability.