Geographical distribution, tree density and fruit production of Tamarindus indica (Fabaceae) across three ecological regions in Benin

Abstract

Introduction. The conservation status of many wild fruit tree species that support rural people in Africa remains poorly documented despite its importance for their management. We compared the viability of tamarind (Tamarindus indica) populations, a dry land species that has nutritional, medicinal and cultural importance for rural communities, under different human-pressure levels. Materials and methods. Conservation status of the species’ populations from different habitat types was characterised using sampling data from forest inventories, dendrometric characterisation and diameter size distributions. Dendrometric characteristics were analysed using non parametric tests and size structures were fitted to a truncated normal distribution. Results and discussion. Numbers of mature tamarind trees per hectare and regeneration (expressed as stem•ha–1) were relatively low, suggesting tamarind populations may not be self-rejuvenating. Nonetheless, significant variation occurred between habitat types (P < 0.001). Mature tree density in gallery forests [(18.2 ± 10.1) trees•ha–1] was three to eight times higher than that of savannah woodlands [(5 ± 4.5) trees•ha–1] and farmlands [(2.5 ± 0.4) trees•ha–1]. Young plants followed the same trend, with [(11.2 ± 9.3) plants•ha–1], (1.1 ± 0.6) plants•ha–1], and 0.00 plants•ha–1], respectively. Diameter size class distributions departed from normality (P < 0.0001) and coefficient of skewness was positive irrespective of habitat types, indicating declining populations. However, median diameter values would suggest the species’ populations in farmlands and savannah woodlands to be more vulnerable than those occurring in gallery forests. These findings would suggest that gallery forests best suit to tamarind in situ conservation. The observed severe reduction of trees and juveniles in farmlands and woodlands may negatively impact the long-term viability of tamarind populations. Juveniles’ introduction in farmlands may be needed to ensure circa situ conservation.