Wednesday, January 10, 2007

Tropical Vegetation

High temperature and abundant rainfall in the equatorial regions support a luxuriant type of vegetation -the tropical rain forest.

A great variety of vegetation:

The equatorial vegetation comprises a multitude of evergreen trees that yield tropical hardwood, e.g. mahony, ebony, greenheart, cabinet woods and dyewoods. - There are smaller palm trees, climbing plants like the lianas or rattan, which may be hundreds of feet long and epiphytic and parasitic plants that live on other plants. - Under the trees grow a wide variety of creepers, ferns, orchids and “lalang”.

A distinct layer arrangement:

From the air, the tropical rain forest appears like a thick canopy of foliage, broken only where it is crossed by large rivers or cleared for cultivation. - All plants struggle upwards for sunlight resulting in a peculiar layer arrangement. The tallest trees attain a height of over 150 feet. Their slander trunks pierce skywards with widespread branches at the top. The smaller trees beneath from the next layer, and the ground are rooted with ferns and herbaceous plants, which can tolerate shade. Because the trees cut out most of the sunlight the undergrowth is not dense.

Multiple species:

Unlike the temperature forests, where only a few species occur in a particular area, the trees of the tropical rain forests are not found in pure stands of a single species. - It has been estimated that in the Malaysian jungle as many as 200 species of trees may be found in acre of forest. This has made commercial exploitation of tropical timber a most difficult task.

Many of the tropical hardwoods do not float readily on water and this makes haulage an expensive matter. It is therefore not surprising that many tropical countries are net timber importers!