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close this bookBasic Concepts in Environment, Agriculture and Natural Resources Management: An Information Kit (International Institute for Rural Reconstruction (IIRR))
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View the documentTropical forest -ecosystems
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Tropical forest -ecosystems


Tropical forest -ecosystems

Tropical forest -ecosystems

Tropical forest ecosystems are situated in the equatorial belt of the earth. This portion of the earth is called the tropical zone. It-accounts for about 40 percent of earth's surface; Within this zone are two major types of tropical forest ecosystems: (1) the rainforest; and, (2) the monsoon or seasonal forest. Both types of forest ecosystems exist in the-Philippines. The latter occupies 6.7. million hectares of the available land area.

The rainforest is one of the oldest and most complex ecosystems on earth.

Extensive rainforest regions

The Amazon River Basin in South America, the Congo River Basin in equatorial Africa and the Malay Archipelago in Southeast Asia.

Philippine forests

Kalinga-Apayao Mountains, Sierra Madre Mts., Palawan, Northern Samar, Mindoro, Agusan, Surigao - del Sur and Bukidnon Mt.


Remaining old growth forest areas in the Philippines

Forest Areas in the Philippines

Types of Forest Area

(m has)

Dipterocarps

2.435

Mossy/marginal

0.2455

Mangroves

0.1494

Pines

0.0812

Beach

(no data)

Molave

(no data)

Adapted from DENR, 1990.

Ecological importance of tropical forests

  • Maintenance of a well-balanced local, regional and or global climates. Vegetation can affect-climate in several different ways, via heat balance, surface roughness, the hydrological cycle (precipitation and evapotranspiration) and carbon storage.
  • As a living storehouse of biodiversity. Reduction in structural diversity inevitably follows from human interaction with- tropical rainforests as they are progressively simplified by increasing degrees of interference, e.g., timber utilization. The mast deleterious effects would be to see the trees and not the animals or vice versa. Biodiversity has a life-sustaining effect to human beings.
  • Natural protection against human impoverishment. Human population located in the tropics depends on the forest resource base for its basic sustenance. The disappearance of the forest through massive disturbances in the forest ecosystem would also mean loss of hut man lives.


Forest ecosystem threats

The direct threets to forest ecosystems in the Philippines are:

Forest conversion

  • Logging. It is estimated that fogging activities destroy forests et a rate of 100,000 hectares per year (DENR,
  • Subsistence/Permanent Farming. The conversion of forests to other land uses. In 1980 alone, about 210,000 ha were deforested and converted into agricultural land use. This trend is increasing at the rate of 200,000 ha/year.
  • Aquaculture. Philippine mangrove forests have decreased in size by 99% since 1920. Mostly due to conversion to aquaculture.


Wildlife trade

  • In 1990-91, the Philippines exported about 84,668 heads of mammals, 4,188 heads of birds, 516 heads and specimens of reptiles and 130,775 pieces of orchids and 4,510 pieces of insects.


Other issues and threats

  • Watershed Denudation. Nineteen out of 58 major watersheds are critically denuded, reducing their hydroelectric and irrigation potentials, as well as their water regulation functions.
  • National Parks. This covers 381,549 has. Only seven out of 77 national parks now meet international standards, due to squatting, illegal logging, kaingin and subdivision.
  • Loss of Biodiversity. This is indicated by the fact that our list of endangered species contains 18 entries. Another 25 are in the threatened list. Many of these plants and animals reside in rapidly disappearing forests. 50 percent of our endemic forest flora are already extinct.


Effects and implication

  • Physical. Soil is exposed to wing and rain, therefore, increasing erosion. Loss of root structure can cause landslides end crop losses; silt raises riverbeds leading to floods; siltation on inland water bodies end coastal areas; depletion of biotic species inland and in the coastal areas; and, loss of forest biodiversity.
  • Sociocultural and Economic. Unemployment; export receipt diminution; degradation of cultural values and norms; development projects are resisted and aborted; dislocated communities (environmental refugees); and, more impoverished workers and upland occupants.