Content
Introduction
The kerangas forests of Borneo are a highly unusual form of tropical rain forest that appear to be determined by the substrate that the forests are growing on. They are characterized by large numbers of very small trees, often with a limited number of tree species present at a particular site. Various forms exist, and all may occur within a particular patch of kerangas.
Considerable debate exists over the environmental determinants of this type of forest. They are clearly determined by the substrate, with the best development being seen on podsols. The substrate can be either sandy beaches or sandstone plateaus, although the vegetation type has also been recorded on narrow ridges. The soils hold very little water, suggesting that moisture limitations may be the key environmental determinant. However, they are also highly leached and very acidic, and so nutrient limitation may be the most important environmental factor. The answer may lie in a combination of these two determinants.
Outcomes
By the end of this topic, you should be able to:
- Define heath forests and describe their main characteristics
- Indicate where the most important areas of kerangas are located
- Distinguish between kerangas and padang
- Explain the most important traits of trees surviving in kerangas forests
- Assess the relative importance of moisture deficits and nutrient deficiencies in determining the vegetation found in kerangas forests
Readings
Optional Readings
- Ashton, P. 2014. On the forests of Tropical Asia. Lest the memory fade. London, UK: Kew Publishing. 670 pp.
- Brünig, E.F. 1974. Ecological studies in the kerangas forests of Sarawak and Brunei. Kuching, Sarawak : Borneo Literature Bureau for Sarawak Forest Department.
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 5.1.6" 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 kerangas forests, and answer/respond to at least one other question on the discussion board Case Study 6 Discussion - Kerangas Forests of Borneo.
Summary
Kerangas forests are relatively rare, covering a tiny proportion of the forest area of Borneo. However, they are sufficiently unusual to have drawn the attention of several forest ecologists. They show a number of characteristics, and are noted for the high numbers of carnivorous plants (especially Nepenthes spp.) and myrmecophytes. Many of the plant species associated with kerangas are only found in this habitat, but their extent is too small to have allowed the evolution of unique bird or mammal species. The invertebrates of kerangas forests have not been studied in any detail, and it is possible that there may be some unique species associated with this vegetation type.
An ongoing debate exists over the relative importance of moisture limitations and nutrient deficiencies in determining the plants found in kerangas and their respective traits. The presence of traits associated with both these determinants suggests that a combination of factors may be involved.
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:
- How are heath forests defined, and what are their main characteristics?
- Where are the most important areas of kerangas located?
- What are the differences between kerangas, kerapa and padang?
- What are the primary traits of trees surviving in kerangas forests?
- What is the relative importance of moisture deficits and nutrient deficiencies in determining the vegetation found in kerangas forests?
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