Philippine old growth forests were dominated by dipterocarp forests, which contain a mixture of varied dipterocarp trees along with timber species of other plant families (e.g., Mimosaceae, Moraceae, Fagaceae, Sapotaceae, Myrtaceae, Euphorbiaceae) and numerous members of lesser-used species. Dipterocarp forests have been major sources of raw material for lumber, veneer and plywood, furniture wood and other hardwood-based products. They are located in higher elevations of Luzon, Palawan, Visayas and Mindanao, particularly in regions where precipitation is highest. Today, much of the remaining old-growth and second-growth dipterocarp forest are located in Regions II, IV, X and XI. Old-growth dipterocarp trees of large diameter sizes (at least 55 centimetres at breast height) now compose only 16 percent of all trees.
Figure 1 Dynamics of
The process of deforestation follows a series of stages beginning with high extraction rates in terms of high volume removal, extensive area cut, and logging damage, ineffective protection of cut-over forest, intrusion by secondary loggers, and conversion into non-forest uses (Figure 1). During the period 1970-1989, the exploitation of old-growth forest occurred at a rate of 210,000 hectares annually; on the other hand the gain in secondary area was only 11,000 hectares per year, implying further conversion into non-forest uses.
Since depreciation of resources in forest land occurs in terms of declining stocks of various forests species as well as removal of top layers of soils in forest lands as a result of erosion, this report integrates the results of both the forest and upland soils depreciation studies. The studies were generated by several phases of the Philippine Environmental and Natural Resources Accounting Project (ENRAP), an undertaking of the Department of Environment and Natural Resources (DENR) funded by the United States Agency for International Development (USAID).
Section 2 presents a detailed treatment of soil resources accounting in upland areas of at least eight percent slope. Three approaches are explored, including the change in asset value as affected by reduction of lifetime, productivity changes and replacement cost approaches. Comparisons are made and relevant policy implications are discussed.
Section 3 summarizes the results for dipterocarp forest resources and Section 4 presents an integration of the two accounting results with emphasis on forest-land-based resources. Recommendations for further methodology development and data refinement are discussed briefly.