Introduction

In this case study, we look at the spiny forests ecoregion of southern Madagascar. This is an example of dry tropical forest area, with the dominant vegetation type being known as spiny forest-thicket. It can be divided into a number of regions, each with a distinctive flora and fauna. The geology also varies between regions and, to a certain extent, the regions are defined by the geology. For example, the Limestone Plateau region is an area of karst, delimited by the occurrence of limestone substrate.

Madagascar presents a fascinating case study because of the uniqueness of its flora and fauna. There are large numbers of endemic species, and eight plant families are endemic to Madagascar and the islands in the Indian Ocean. The Spiny Forest contains 2100 vascular plant species, with 53% of the species being endemic to the ecoregion. Eight genera are endemic, including Alluaudia and Didierea. The plants found in the Spiny Forest are primarily woody, with few herbaceous species. They show a number of traits characteristic of an arid and unpredictable climaye, including succulence, spinescence, pachycauly, deciduousness and leaflessness.

All non-flying mammals in Madagascar (with the exception of introduced species) are endemic. The 170 species belong to only four families: tenrecs, lemurs, carnivores and rodents. The mammal fauna has seen recent depletions: at least 25 species have disappeared since the first arrival of humans on the island. There are 44 mammals that have been recorded from the Spiny Forest, but most of these are very poorly known, and some are only known from one or two records.  20 species of mammals in the Spiny Forest are bats.

Outcomes

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

• Describe the unique nature of Madagascar’s Spiny Forest ecoregion
• Explain the reasons for the very high levels of endemism in this forest, as well as in Madagascar
• Compare the life histories of some of the species with those in more humid forest types

Readings

Optional Readings

• Goodman, S.M. and Benstead, J.P. (eds.) 2003. The Natural History of Madagascar. Chicago, Illinois, London: University of Chicago Press. 1709 pp.
• Jasper, L. and Gardner, C. 2015. Life amongst the thorns. Biodiversity and conservation of Madagascar’s Spiny Forest. Oxford, UK: John Beaufoy Publishing. 318 pp.

Fundamental Concepts

PPT Presentations

This module contains one presentation:

5.1.9 Case study - Madagascar's Spiny Forest.pptx Download 5.1.9 Case study - Madagascar's Spiny Forest.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 5.1.9' 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 Madagascar's Spiny Forest, and answer/respond to at least one other question on the discussion board Case Study 9 Discussion - Madagascar's Spiny Forest.

Summary

The Spiny Forest of Madagascar lies at the dry end of the spectrum of tropical forests. It illustrates that dry forests can hold considerable diversity. many of the plants and animals are specifically adapted to life in an arid environment and display traits that are characteristic of dryland species. Madagascar's isolation for the last 80 million years has resulted in the development of a unique flora and fauna, and levels of endemism are extremely high. The ecology of many species is largely unknown - numerous species have yet to be formally described.

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 some of the more unusual traits shown by trees in Madagascar’s Spiny Forest ecoregion?
• Why are there very high levels of endemism in this forest, as well as in Madagascar?
• How do the life histories of species in the spiny forest with those in more humid forest types?