Cataloguing grasses of Madagascar shows natural diversity
A new assessment of the grass species of Madagascar has shown a rich and ancient grass flora that evolved on the island. Maria Vorontsova, a taxonomist specialising on tropical grasses (botanical family Poaceae) identified 541 species, including 217 endemics (those found only in Madagascar). A similar number of endemics can be found on other subtropical islands, and different endemic species are restricted to specialised habitats across Madagascar, as expected for natural ecosystems.
Ecological analysis: which grasses grow together?
Maria collaborated with a team of researchers from Madagascar and other countries to record which grasses occur together in both natural and disturbed habitats. Molecular and statistical analyses have shown that environments with high levels of grazing have grass species that are more closely related to each other, indicating that high levels of grazing are not natural for these environments. Burning does not change how closely related the grasses are, indicating that fire could be a natural part of the ecosystems.
Grasslands and savannas are a natural part of Madagascar
Exploration of tropical areas has traditionally focused on forests, partly due to their economic value. Open canopy areas have been historically undervalued and often not recognised as natural ecosystems rich in diversity. This study will help redress the balance and encourage the appreciation of savannas and grasslands as valuable parts of Madagascar’s landscapes.
Which grasslands are ancient?
Tropical landscapes where fires are present are often a vegetation mosaic which changes over time. The same location can be either natural forest, or natural savanna, without any human influence causing this change. But how do we recognise these ancient grasslands and how do they differ from recently created pastures which are maintained by regular burning? This question will be the subject of continued research by Maria and her colleagues.
Vorontsova*, M.S., Besnard, G., Forest*, F., Malakasi*, P., Moat*, J., Clayton*, W.D., Ficinski*, P., Savva, G.M., Nanjarisoa*, O.P., Razanatsoa, J., Randriatsara*, F.O., Kimeu, J.M., Luke, W.R.Q., Kayombo, C. & Linder, H.P. (2016). Madagascar’s grasses and grasslands: anthropogenic or natural? Proceedings of the Royal Society B: DOI: 10.1098/rspb.2015.2262. Available online