Diversity of grasses (Poaceae) in southern Africa, with emphasis on the conservation of pasture genetic resources

Abstract

A renewed interest in the present state of genebanks conserving pasture genetic resources worldwide motivated this study to quantify the wealth of grass (Poaceae) diversity indigenous to southern Africa, here defined as South Africa, Lesotho and Eswatini (previously Swaziland). Botanical occurrence records were extracted from BODATSA and PHYTOBAS datasets to generate a list of grass species indigenous to the study area. The phylogenetic classification, growth form, photosynthetic pathway, grazing status, endemism and conservational status attributes were added to the 43,889 species level records, sourced from published literature. Results from the current study indicate that the subcontinent is represented by eight subfamilies, 25 tribes, 151 genera and 685 species, inferring that only 20% of the world’s grass genera and 6% of world’s grass species are found in the study area with Panicoideae the most speciose subfamily. Paniceae is the only tribe with large numbers of both C₃ and C₄ species and with several species of high grazing value, therefore, was suggested as a priority lineage in the collection and conservation efforts of the South African National Forage Genebank. This genebank conserves at present 73 genera and 162 indigenous grass species, i.e. 48% and 24% of the total number of taxa respectively, denoting the current vulnerable status of grass genetic resources in southern Africa. A need to therefore collect and conserve grass genetic resources is emphasised, with greater focus on the conservation of seed of well-known pasture genera classified as endangered or possibly extinct (mainly Panicum L. and Secale L.).