Cover Image
close this bookBasic Concepts in Environment, Agriculture and Natural Resources Management: An Information Kit (IIRR, 1993, 151 p.)
close this folderIntroduction
View the documentUse of workshop
View the documentWorkshop participants
View the documentSupport staff
View the documentGlossary of commonly used environmental terms
View the documentList of references
close this folderEcological basics
View the documentEcosystem degradation
View the documentHabitat and niche
View the documentThe food chain
View the documentBiological magnification
View the documentNitrogen cycle
View the documentSociety and the carbon-oxygen cycle
View the documentHealth consequences of environmental degradation
View the documentPopulation and the environment
close this folderFreshwater and marine ecosystems
View the documentFreshwater ecosystems
View the documentEstuarine-mudflat ecosystems
View the documentSeagrass ecosystems
View the documentMangrove ecosystems
View the documentCoral reef ecosystems
View the documentHuman intrusions into the water cycle
View the documentDiversity of coastal and marine resources
View the documentPhilippine marine fisheries
View the documentMarine turtles
View the documentMarine food web
View the documentOcean pastures
View the documentThe menace of algal bloom
View the documentRed tide (Dynamics and public health aspects)
close this folderForest ecosystems
View the documentTropical forest -ecosystems
View the documentProtected areas: a tool for biological diversity conservation
View the documentEnvironmental effects of overexploitation for fuelwood in nearshore coastal resources
View the documentBiological diversity: and wildlife conservation
View the documentWildlife trade
close this folderGlobal warming and acid rain
View the documentClimate change and the greenhouse effect
View the documentHow deforestation contributes to the greenhouse effect
View the documentAcid rain
close this folderPollution
View the documentToxic and hazardous wastes
View the documentPollution and long-term effects on the human body
View the documentUrban pollution: The metro Manila environment
View the documentMining operations: environmental effects on soil, water, communities and atmosphere
View the documentPesticides: environmental and health effects
close this folderOthers
View the documentPhilippine commercial energy sources, 1990
View the documentCommon property resources in crisis
View the documentDegradation of the uplands
View the documentLowland degradation
View the documentEnvironmental issues in animal production
View the documentPlant genetic resources
View the documentNatural hazards

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)










(no data)


(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.