Impact of habitat type on the conservation status of tamarind (Tamarindus indicaL.) populations in the W National Park of 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. The data relative to the tree diameter and height as well as the number of adults and stems were collected in plots of inventory and made it possible to calculate the dendrometric parameters for each targeted population, and to establish their diameter distribution. The dendrometric characteristics were analyzed by using nonparametric tests and the diameter distribution was adjusted 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 type, 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 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 into farmlands may be needed to ensure conservation in agroforestry systems.