A GIS-BASED MODEL TO IMPROVE ESTIMATION OF ABOVEGROUND BIOMASS OF SECONDARY FORESTS IN THE PHILIPPINES

Abstract

MAGCALE-MACANDONG, D. B., DELGADO, M. E. M., TY, E. & VILLARIN, J. R. T. 2006. A GIS-based
model to improve estimation of aboveground biomass of secondary forests in the Philippines. A geographic
information system (GIS)-based model was developed to spatially predict the aboveground biomass of
secondary forests in the Philippines. A database of the physical (soil type, slope, elevation) and climatic
(agroclimate zone, annual rainfall) properties of the different administrative units (provinces) in the country
was assembled from secondary data and existing maps. Thematic maps of each of the above physical and
climatic properties were developed for the whole country. Published data on diameter at breast height
(dbh) of sampled trees in secondary forests, and plantations of Swietenia macrophylla and Dipterocarpus sp.
were used to estimate aboveground biomass using allometric regression equation. The relationship of the
physical and climatic factors (independent or predictor variables) and the forest aboveground biomass
(dependent variable) was determined through multiple linear regression analysis. The resulting equation
was used to predict potential aboveground biomass of secondary forests in the country. Overlaying the
potential biomass map to the remaining secondary forest areas resulted in a map of the estimated
aboveground biomass of secondary forests. The study demonstrated the potential of GIS in estimating
forest biomass at different locations and environmental conditions. The GIS-based model can be further
improved with the availability of tree biomass data and digital maps.