Introduction

The Western Ghats are a mountain range that extend down almost the entire the western coast of India. There is a pronounced north-south climatic gradient, with the length of the dry season increasing northwards. There is also a strong east-west gradient, with rainfall decreasing markedly in the rain shadow of the eastern slopes of the mountains. The vegetation reflects the complex history of India, which was originally a part of Gondwana but then drifted northwards before ultimately colliding with the Asian plate. The rain forests that today occur in the Western Ghats and Sri Lanka represent the remnants of what were once (about 10-15 million years ago) much more widespread rain forests.

Most of the forests of the Western Ghats have either been destroyed or heavily disturbed, and only 7% of the primary vegetation cover remains. The most frequent forest types are tropical semi-evergreen forest, tropical wet evergreen forest and moist deciduous forest. A coastal belt of tropical evergreen forest forest once existed, but has long since been destroyed by development. The degree of disturbance makes it difficult to determine what the original composition of the forests might have been like, but dipterocarps may have been relatively common.

The forests contain large numbers of endemic species, reflecting their degree and length of isolation. Of the 4780 plant species that have been documented, 45.6% are endemic. 220 amphibian species have been described from the region, of which 78% are endemic. The extent of forest loss, particularly in the coastal forests, suggests that many species may have been lost before they were described.

Outcomes

By the end of this topic, you should be able to:

• Describe the different forest types found in the Western Ghats
• Explain their origins
• Discuss the reasons behind the very high levels of endemism found within these forests
• Give examples of taxonomic groups that have unusually high levels of endemism in the Western Ghats
• Compare these forests with other tropical forests

Readings

Optional Readings

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Fundamental Concepts

PPT Presentations

This module contains one presentations:

5.1.7 Case study - Western Ghats, India.pptx

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 5.1.7' 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 forests in the Western Ghats of India, and answer/respond to at least one other question on the discussion board Case Study 7 Discussion - India's Western Ghats.

Summary

The Western Ghats are seldom included in texts about rain forests, despite the large numbers of endemic and endangered species that they contain. As a result, they are not particularly well-known outside of India. Interest however is increasing, and more and more information about the structure, composition and ecology of the forests in the region is emerging.

The very high levels of endemism reflect the unusual history of India. It is not a part of the Asian plate and, as a result, its flora and fauna evolved relatively independently after the separation from Gondwana (and the later separation from Madagascar). The forests of the Western Ghats are separated from other rain forests in Asia by broad areas of arid and semi-arid country and so, after contact with the Asian plate, there has been limited movement of Asian species into the Western Ghats.

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 characteristics of the different forest types found in the Western Ghats?
• What is the origin of these geographically isolated forests?
• Why are there so many endemic species in these forests?
• Are there particular taxonomic groups that have unusually high levels of endemism in the Western Ghats?
• How do these forests compare with other tropical forests that you are familiar with?