Content
Introduction
The Mascarene Islands comprise an archipelago of three islands in the Indian Ocean: Mauritius, Rodrigues and La Réunion. The islands have never been connected to land or each other, and were formed fairly recently. Mauritius emerged about 8 million years ago, La Réunion 5 million years ago and Rodrigues 1.5 million years ago. The climate of each island differs markedly, with La Réunion having the most complex climate.
On Mauritius and La Réunion, dense forests existed when the first Europeans encountered them. Rodrigues had a more open forest which has been attributed to the high density of giant tortoises that were living there. The fauna was adapted to episodic food shortages caused by the loss of flowers and fruits following severe storms. As would be expected, the forest varies in structure and composition depending on environmental determinants such as climate, altitude and soil type.
Since the arrival of European colonists, much of the vegetation has been destroyed, especially on Mauritius and Rodrigues. On Mauritius, less than 1% of the indigenous forest survives today. Many remnant patches on Mauritius are under pressure from introduced exotics, such as Ligustrum robustum var. walkeri, Rubus alcefolius, and Psidium cattleianum. Invasive species, such as Furcrea foetida, Lantana camara, Syzygium jambrosa and Acacia nilotica, are also threatening the remnant vegetation on Rodrigues.
Outcomes
By the end of this topic, you should be able to:
- Summarize the differences between the three Mascarene Islands
- Explain the origins of the floras of each of the islands and describe their differences
- Describe the main forest types found on the islands and their environmental determinants
- Discuss the ecological implications of the extinction of the Dodo on Mauritius
Readings
Optional Readings
- Cheke, A. and Hume, J. 2008. Lost Land of the Dodo. An Ecological History of Mauritius, Réunion & Rodrigues. New Haven, USA and London, UK: Yale University Press. 464 pp.
- Gurib-Fakim, A. and Seenauth, R. 2019. Floral Biodiversity of the Mascarene Islands: Our Legacy to the World. Singapore: SGM Knowledge Pte Ltd. 297 pp.
Self-check Quiz (For certificate learning only)
After viewing topic presentations, take this self-check quiz to check your own progress. This quiz is designed to see how well you remember some of the issues presented in the topic. There are five questions, and each has a potential of 4 answers, only one of which is correct. When you are ready, click the link 'Self-check Quiz 5.1.10' to start taking the quiz.
Case Study Discussion (For certificate learning only)
Once you have have read the presentation, post a question about the ecology of the Mascarene Islands, and answer/respond to at least one other question on the discussion board Case Study 10 Discussion- The Mascarene Islands.
Summary
The Mascarene Islands present an example, and a lesson, of what can happen on isolated islands. They differ from many other islands in that there were no (known) human inhabitants prior to European colonization. Early visitors saw the native flora and fauna as a resource to be exploited, resulting in the rapid loss of many species. The Dodo is the best-known example, but there were many others. The remnant flora and fauna continue to suffer as a result of the impacts of invasive species, and the increasing populations on the islands will undoubtedly continue to exert pressures o the remaining native vegetation. La Réunion has the greatest area of relatively intact ecosystems, protected by the inaccessibility of some areas.
Self-review (For self learning)
To review what you have learned in the topic, you are encouraged to use the following reflection questions as a study guide to do a self-review for the topic:
- What are the principal differences between the three Mascarene Islands?
- What are the origins of the floras of each of the islands and why are they different?
- What are the main forest types found on the islands and what are their environmental determinants?
- What are the ecological implications of the extinction of the Dodo on Mauritius?
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