Inselbergs: potential conservation areas for plant diversity in the face of anthropization

Abstract

Faced with the loss of biodiversity, particularly plant diversity, due to anthropogenic pressure, particular ecosystems such as inselbergs can constitute refuge areas. The objective of this study is to determine the conservation potential of plant biodiversity on inselbergs in Burkina Faso. A comparative study was carried out between inselberg’s vegetation and the surrounding plains vegetation. In each of these vegetation types, stratified and random sampling was adopted and data were collected in plots of 900 m² for the woody stratum and 100 m² for the herbaceous stratum. The specific diversity was evaluated through the effective numbers of Hill of order Q = 0; 1; 2. The Hill index does not vary between inselbergs and plains and thus reflects a strong similarity in floristic diversity between the two ecosystems. Sorensen’s similarity coefficient also shows a similarity in terms of floristic composition between inselbergs and surrounding plains. In inselbergs, relict species that have disappeared from the surrounding plains of some phytogeographic sectors occur. The flora of inselbergs is also characterised by indicative species of anthropized ecosystem absence. However, these species are present on the surrounding plains. Indeed, the flora of inselbergs is characterised by 11 endemic species. Inselberg’s vegetation is characterised by unique plant communities such as rock pools and Afrotrilepis pilosa mats. The exploitation and mortality rates of woody plants are significantly higher on the surrounding plains than on the inselbergs. The flora and vegetation of inselbergs show the absence of indicator species of disturbed ecosystems. They present endemic and relict species and stable woody stands. Due to the steep slope, lack of suitable soil for agriculture and sacred status of someones, the inselbergs constitute a refuge for plant species and thus contribute to the conservation of biodiversity like the protected areas.

Plant communities on inselbergs in Burkina Faso

“…The high value of Piélou's equitability index indicates the absence of species dominance in the various groupings described, both for savannah groupings and for grassland and pasture groupings. These high values also show that the plant communities of inselbergs in Burkina Faso are not subject to major disturbances [ 6 ]. showed that inselberg vegetation is less disturbed than vegetation on the surrounding plains.…”

“…[ [2] , [3] , [4] ]. Inselbergs are characterized by their isolation from the surrounding relief and their independence from the regional hydrological network [ 5 , 6 ]. Inselbergs are distinct ecosystems due to the nature of their substrate, and vegetation [ 7 , 8 ].…”

Ecologie et mécanismes d’adaptation à la sécheresse de <i>Caralluma adscendens</i> N.E.Br. à l’Ouest du Burkina Faso

“…Malgré la précarité de leurs conditions microclimatiques et édaphiques très particulières (fortes insolations et évapotranspirations, plus ou moins existence de la couverture du sol), des études ont montrés que les inselbergs abritent une diversité floristique riche et caractéristiques en Côte d'Ivoire, en Guinée, au Bénin et au Burkina Faso (Kouassi et al, 2014;Tindano et al, 2015). De plus ces milieux constituent des refuges pour de nombreuses espèces végétales dans les régions à forte pression anthropique (Tindano et al, 2023b), et constituent des habitats particuliers aussi bien de par la nature de leur substrat que par la flore et la végétation. Certaines espèces végétales colonisent les inselbergs et sont associées à ce type de biotope du nord au sud du Burkina Faso.…”