Madagascar's grasses and grasslands: anthropogenic or natural?

Maria S Vorontsova, Guillaume Besnard, Félix Forest, Panagiota Malakasi, Justin Moat, W Derek Clayton, Paweł Ficinski, George M Savva, Olinirina P Nanjarisoa, Jacqueline Razanatsoa, Fetra O Randriatsara, John M Kimeu, W R Quentin Luke, Canisius Kayombo, H Peter Linder

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)
8 Downloads (Pure)

Abstract

Grasses, by their high productivity even under very low pCO2, their ability to survive repeated burning and to tolerate long dry seasons, have transformed the terrestrial biomes in the Neogene and Quaternary. The expansion of grasslands at the cost of biodiverse forest biomes in Madagascar is often postulated as a consequence of the Holocene settlement of the island by humans. However, we show that the Malagasy grass flora has many indications of being ancient with a long local evolutionary history, much predating the Holocene arrival of humans. First, the level of endemism in the Madagascar grass flora is well above the global average for large islands. Second, a survey of many of the more diverse areas indicates that there is a very high spatial and ecological turnover in the grass flora, indicating a high degree of niche specialization. We also find some evidence that there are both recently disturbed and natural stable grasslands: phylogenetic community assembly indicates that recently severely disturbed grasslands are phylogenetically clustered, whereas more undisturbed grasslands tend to be phylogenetically more evenly distributed. From this evidence, it is likely that grass communities existed in Madagascar long before human arrival and so were determined by climate, natural grazing and other natural factors. Humans introduced zebu cattle farming and increased fire frequency, and may have triggered an expansion of the grasslands. Grasses probably played the same role in the modification of the Malagasy environments as elsewhere in the tropics.  

Original languageEnglish
Article number20152262
JournalProceedings of the Royal Society B: Biological Sciences
Volume283
Issue number1823
DOIs
Publication statusPublished - 20 Jan 2016

Keywords

  • Poaceae
  • neogene
  • endemism
  • species turnover
  • phylogenetic community assembly

Cite this