Content
Introduction
The Philippines archipelago represents a geologically complex set of islands that differ in their origins and histories. Igneous, metamorphic and sedimentary geologies are all represented. Areas of karst and ultramafic rocks have their own types of specialized vegetation. The climate is complex, and dominated by the southwest and northeast monsoons. Some areas are more seasonal than others, with rainfall ranging from 900 mm to 4500 mm, and this is reflected by the forest types. Typhoons are common during the wet season, and can cause significant disturbance in the forests.
Although some forest types are now very rare on some islands due to deforestation, good descriptions of many forests were obtained in the early 20th century. However, even then, some lowland forests had been completely cleared in some areas. Dipterocarps are important at lower elevations, similar to other parts of Malesia.
Many of the mountains have distinct elevational gradients, and these have been described in detail. The forest passes through a number of forms, ranging from lowland humid rain forest at the lowest elevation to mossy forest at the highest elevations. The mossy forest consists of trees 6–8 m tall, and is often dominated by Podocarpaceae.
Outcomes
By the end of this topic, you should be able to:
- Compare the origins of different Philippine islands
- Describe the main forest types found on the islands
- Contrast the compositions of these forests
- Explain why the flora of Palawan has more similarities to the island of Borneo than it does to the island of Luzon
- Describe how the forests in the Philippines change with altitude
Readings
Optional Readings
- Fernando, E.S., Suh, M.H., Lee, J., Lee, D.K. 2008. Forest Formations of the Philippines. Seoul, Republic of Korea: ASEAN-Korea Environmental Cooperation Unit.
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 5.1.3' to start taking the quiz.
Summary
In this topic, we have looked at the forests of the Philippines. The Philippines are part of Malesia, and the flora has many affinities to other parts of Malesia. In particular, many of the forests are either dominated by Dipterocarpaceae, or species from within this family form an important component of the forest communities.
The flora shows some broad trends that can be related to the distribution of rainfall, with some areas experiencing relatively dry climates and others having moist tropical climate. In addition, altitude adds another dimension to the variation in forest communities. Further sources of variation are edaphic, and the very varied geology of the Philippines is reflected in the variety of specialized forest types, such as those found on ultramafic rocks.
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 did the Philippine islands originate?
- What are the main forest types found on the islands?
- How do these forests differ in their composition?
- Why does the flora of Palawan have more similarities to the island of Borneo than it does to the island of Luzon?
- How does the composition of Philippine forests change with altitude?
|
|