Flora of Madagascar

The flora of Madagascar is exceptionally unique and biodiverse, with more than 80 percent of the island's 14,883 plant species found nowhere else in the world. The prehistoric breakup of the supercontinent Gondwana separated the Madagascar-Antarctica-India landmass from the Africa-South America landmass around 135 million years ago. Madagascar later split from India about 88 million years ago, allowing plants and animals on the island to evolve in relative isolation.[1] This distinctive ecology has led some ecologists to refer to Madagascar as the "eighth continent",[2] and the island has been classified by Conservation International as a biodiversity hotspot.[3]

Much of the island was originally forested, but nearly all this forest cover has been lost due to increasing global temperatures and human deforestation. The largest remaining stretch of old growth rain forest lies along the eastern coast of the island. The western and southern sides of the island, which lie in the rain shadow of the central highlands, are home to dry deciduous forests, spiny forests, and deserts and xeric shrublands. Due to their lower population densities, Madagascar's dry deciduous forests have been better preserved than the eastern rain forests or the original woodlands of the central plateau.[4]

Five plant families are endemic to Madagascar.[5] There are several endemic families including the Asteropeiaceae, Sarcolaenaceae and Sphaerosepalaceae. The humid eastern part of the island was formerly covered in rainforest with many palms, ferns and bamboo, although much of this forest has been reduced by human activity. The west has areas of dry deciduous forest with many lianas and with tamarind and baobabs among the dominant trees. Subhumid forest once covered much of the central plateau but grassland is now the dominant vegetation type there. The family Didiereaceae, composed of four genera and 11 species, is limited to the spiny forests of southwestern Madagascar.[6]

Four-fifths of the world's Pachypodium species are endemic to the island.[7] Three-fourths[8] of Madagascar's 860[5] orchid species are found here alone, as are six of the world's eight baobab species.[9] The island is home to around 170 palm species, three times as many as on all of mainland Africa; 165 of them are endemic.[8] Many native plant species are used as herbal remedies for a variety of afflictions. The drugs vinblastine and vincristine, used to treat Hodgkin's disease, leukemia and other cancers, were derived from the Madagascar periwinkle.[10] The traveler's palm, known locally as ravinala[11] and endemic to the eastern rain forests,[12] is highly iconic of Madagascar and is featured in the national emblem as well as the Air Madagascar logo.[13]

Habitat destruction threatens many of Madagascar's endemic species and has driven others to extinction. In 2003 Ravalomanana announced the Durban Vision, an initiative to more than triple the island's protected natural areas to over 60,000 km2 (23,000 sq mi) or 10 percent of Madagascar's land surface. As of 2011, areas protected by the state included five Strict Nature Reserves (Réserves Naturelles Intégrales), 21 Wildlife Reserves (Réserves Spéciales) and 21 National Parks (Parcs Nationaux).[14] In 2007 six of the national parks were declared a joint World Heritage Site under the name Rainforests of the Atsinanana. These parks are Marojejy, Masoala, Ranomafana, Zahamena, Andohahela and Andringitra.[15] Local timber merchants are harvesting scarce species of rosewood trees from protected rainforests within Marojejy National Park and exporting the wood to China for the production of luxury furniture and musical instruments.[16] To raise public awareness of Madagascar's environmental challenges, the Wildlife Conservation Society opened an exhibit entitled "Madagascar!" in June 2008 at the Bronx Zoo in New York.[17]

See also

References

  1. ↑ University of Berkeley: Understanding Evolution (October 2009). "Where did all of Madagascar's species come from?". Archived from the original on 19 March 2011. Retrieved 19 March 2011.
  2. ↑ Hillstrom & Collier Hillstrom (2003), p. 50
  3. ↑ Conservation International (2007). "Madagascar and the Indian Ocean Islands". Biodiversity Hotspots. Conservation International. Archived from the original on 24 August 2011. Retrieved 24 August 2011.
  4. ↑ Encyclopaedia Britannica (2011). "Madagascar". Encyclopaedia Britannica. Eb.com. Archived from the original on 25 August 2011. Retrieved 25 August 2011.
  5. 1 2 Callmander, Martin; et. al (2011). "The endemic and non-endemic vascular flora of Madagascar updated". Plant Ecology and Evolution 144 (2): 121–125. doi:10.5091/plecevo.2011.513. Archived from the original (PDF) on 11 February 2012. Retrieved 11 February 2012.
  6. ↑ Vences M, Wollenberg KC, Vieites DR, Lees DC (June 2009). "Madagascar as a model region of species diversification". Trends in Ecology and Evolution 24 (8): 456–465. doi:10.1016/j.tree.2009.03.011. PMID 19500874. Archived from the original (PDF) on 11 February 2012. Retrieved 11 February 2012.
  7. ↑ Lavranos, John (2004). "Pachypodium makayense: A New Species From Madagascar". Cactus and Succulent Journal 76 (2): 85–88.
  8. 1 2 Bradt (2011), p. 38
  9. ↑ Baum DA, Small RL, Wendel JF (1998). "Biogeography and floral evolution of baobabs (Adansonia, Bombacaceae) as inferred from multiple data sets". Systematic Biology 47 (2): 181–207. doi:10.1080/106351598260879. PMID 12064226.
  10. ↑ Foster, Steven (December 2010). "From Herbs to Medicines: The Madagascar Periwinkle's Impact on Childhood Leukemia: A Serendipitous Discovery for Treatment". Alternative and Complementary Therapies 16 (6): 347–350. doi:10.1089/act.2010.16609.
  11. ↑ Ellis (1859), p. 302
  12. ↑ McLendon, Chuck (16 May 2000). "Ravenala madagascariensis". Floridata.com. Archived from the original on 20 March 2011. Retrieved 14 September 2009.
  13. ↑ Lambahoany Ecotourism Centre (24 August 2011). "Nature of Madagascar". Lambahoany Ecotourism Centre. Archived from the original on 24 August 2011. Retrieved 24 August 2011.
  14. ↑ Madagascar National Parks (2011). "The Conservation". parcs-madagascar.com. Archived from the original on 25 August 2011. Retrieved 25 August 2011.
  15. ↑ "Rainforests of the Atsinanana". UNESCO. Archived from the original on 25 August 2011. Retrieved 30 April 2011.
  16. ↑ Bearak, Barry (24 May 2010). "Shaky Rule in Madagascar Threatens Trees". New York Times. Archived from the original on 20 March 2011. Retrieved 20 March 2011.
  17. ↑ Luna, Kenny. "Madagascar! to Open at Bronx Zoo in Green, Refurbished Lion House". Treehugger. Archived from the original on 10 July 2011. Retrieved 11 June 2011.

Bibliography

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