Indicator Value of Different Vascular Plant Families for Overall Plant Diversity in the Savanna Belt of Western Africa (abridged Title: Grasses as Indicators of Plant Diversity)

Detailed plant diversity information is lacking for Africa, as for many other regions in the tropics, therefore we have used our collection and observation databases to search for possible indicator groups. Digitization of specimen label data for Burkina Faso from the Herbarium Senckenbergianum (FR) and the Ouagadougou University Herbarium (OUA) led to a database containing 18 000 specimens. Field observations from about 3700 relevés (Braun-Blanquet method, BIOTA standard relevés, simple inventories) were added to the database and together used to model potential species distributions for Burkina Faso on a ten-minute grid. Genetic Algorithm for Rule-set Production (GARP) was used with temperature, precipitation, humidity, and elevation data. Based on these modeled distributions, overall vascular plant diversity was correlated to the diversities of the ten commonest families (Poaceae, Fabaceae, Cyperaceae, Rubiaceae, Combretaceae, Euphorbiaceae, Mimosaceae, Asteraceae, Caesalpiniaceae, Malvaceae). Poaceae and Fabaceae turned out to be the most suitable taxa. The value of these families as indicators for assessing biodiversity is discussed. The results are compared to similar analyses based on relevés only. Accepted 2 August 2007.