Ecological drivers of pteridophyte diversity and distribution in Togo (West Africa)

Abstract

The conservation and sustainable management of biodiversity requires an understanding of the biotic and abiotic factors that condition the presence and survival of organisms in natural habitats. The global distribution and ecological hypersensitivity of pteridophytes have made them ideal candidates for studying the impact of biotic and abiotic factors on levels of biodiversity.

This study aims to determine the effect of vegetation cover, human disturbance, and climatic factors on the distribution and diversity of pteridophytes in Togo with a view to guide conservation efforts. Our data comprises 130 plots of 500 m2 representing all ecological zones of the country, complemented by several opportunistic collections. After determining the patterns of pteridophyte distribution, multivariate analysis of variance and the calculation of diversity indicators made it possible to determine the influence of the factors studied.

We found that pteridophyte species diversity and distribution in Togo are strongly influenced by climatic variables, with more than 90% of species diversity being concentrated in the submontane forest areas. Humidity related variables, insolation, and human disturbances are the main drivers of their distribution. Species diversity is positively associated with an increase in humidity, but decreases with increasing insolation and human disturbance. Importantly, our results emphasize the association of specific species to particular conditions created by climate, land cover, and human disturbances, highlighting the role of pteridophyte species as indicators of environmental conditions or exposure to stress. Within humid forest areas, our analysis of the impact of disturbance indicates that about a quarter of the pteridophyte flora of humid forests is sensitive to minor disturbances, whereas almost all rainforest species decline in the face of high levels of disturbance. Agroforests are a particular case of moderately disturbed rainforests, and have the potential to harbour at least 30.5% of Togolese rainforest pteridophyte species diversity.

We conclude that the conservation of pteridophytes in Togo requires the protection of submontane rainforests and the adoption of less destructive practices in terrestrial species habitats in coffee/cocoa-based agroforests.