5.1.10 Case study - The Mascarene Islands

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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

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