Content

Introduction
Readings
Fundamental Concepts
Self Check
Case Study Discussion
Summary
Self Review

Introduction

The Guiana Shield is located in northeastern South America. It extends from Colombia and Venezuela to Brazil, taking in Suriname, Guyana and French Guiana. The exact boundaries are disputed, but many authors include both the highland areas and the surrounding areas of sedimentary deposits, extending to or just north of the Rio Negro in the Amazon Basin. The area includes some spectacular scenery, including the flat-topped tepuis with their unique ecosystems.

The area is considered to be one of the world's biodiversity hotspots, and over 13,000 vascular plant species have been recorded, 40% of which are endemic. The fauna is equally diverse, with 269 amphibian species involved, 54% of which are endemic, and over 1000 bird species, although only about 8% of these are endemic. If the definition involving the largest area is accepted, then the Guiana Shield completely encompasses seven ecoregions, and a further seven are partly located within the area. About 65% of the area lies within the Guianan moist forests ecoregion.

In this topic, we will introduce to these ecoregions and describe some of the species that are associated with them.

Outcomes

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

Describe the different types of forest found on the Guiana Shield
Explain the differences between the forests on the older rocks of the Shield and the surrounding sedimentary basins
Compare the structure and composition of the different forest types
Assess the role of very infertile soils in determining the vegetation composition of tropical forests

Readings

Optional Readings

Hammond, D.S. (ed.) 2005. Tropical forests of the Guiana Shield. Ancient forests in a modern world. Wallingford, UK: CABI Publishing. 528 pp.

Fundamental Concepts

PPT Presentations

This module contains one presentation:

5.1.16 Case study - Tropical forests of the Guiana Shield.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 5.1.16' 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 tropical forests of the Guiana Shield, and answer/respond to at least one other question on the discussion board Case Study 16 Discussion - Tropical Forests of the Guiana Shield.

Summary

The Guiana Shield contains many different ecosystems. Some of these are the typical tall humid evergreen forests that many associate with the humid Tropics. However, others are much more unusual. In particular, the occurrence of areas of savannah creates many questions. Other vegetation types are easier to explain, such as the heath forests found on infertile white sands. The summits of the tepuis have quite unique ecosystems, with numerous endemic species. Most are very inaccessible, and are only now beginning to be documented.

The presence of mon-dominant stands requires further study and explanation. Areas such as the mora, morabukea and wallaba forests are very poorly understood, and would benefit from further study. The area does not appear to have had such a long history of human occupation as some other areas, but this may the result of the lack of evidence to date, rather than a real absence.

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 different types of forest found on the Guiana Shield, and what are their main characteristics?
What are the differences between the forests on the older rocks of the Shield and the surrounding sedimentary basins?
How does the structure and composition of the different forest types found on the Guiana Shield vary?
What is the role of very infertile soils in determining the floral composition of tropical forests?

FODE 008-02