Remote Sensing and GIS for Analyzing and Describing Forest cover Change in the Ancestral Domain of the AGTA in General Nakar, Quezon

Ma. Simeona M. Martinez

Thesis (MS in Remote Sensing)--University of the Philippines Diliman-2008


The designation of national parks and forest lands by the government entails the regulation of some activities such as the allocation of space for certain uses. The Revised Forestry Code’s implementation in 1975 resulted in the designation of lands into Alienable and Disposable (A and D) and Forest Land categories. Agricultural activities or non-forest encroachment in the forest lands pose challenges to the policies that regulate the use of forest resources. When non-forest activities encroach into national parks and protected areas, they show the conflict between actual resource use and the policies that created these parks. This conflict between forest use and protection policies has implications on the utilization of forest resources and on the resource users themselves, such as the Agta indigenous inhabitants of Quezon Province.

This research analyzes the land cover changes in the Kanan Watershed in the municipality of General Nakar, Quezon Province. It describes forest cover changes in the lands and in the area that was designated as a National Park. The information derived from the study can contribute to forest management planning among the various stakeholders of the Kanan Watershed. Landsat images acquired in 1972, 1989 and 2002 were used for the research. Maximum likehood classification was employed to classify each image while post classification change detection through spatial analysis in a GIS environment was also performed to determine stable non-forest and stable forest areas. Knowledge of local resource persons and other information such as land cover data from DENR and NAMRIA guided the selection of classification training areas which relied on visual interpretation of satellite images. Field visits in portions of General Nakar were conducted to verify the training areas.

The examination of three images shows that in areas of the Kanan Watershed that are 18% or above in slope (Forest Land by the Revised Forestry Code of 1975) and are cloudless in all three images, 0.5% has been identified as consistently non-forested since 1972 until 2002, while 61.45% of the area is seen as stable forest for the period. Change from forest to non-forest cover has been increasing through the years, with non-forest encroachment even reaching up to the 40% slope, which is beyond the 18% slope that is set as the limit of A and D lands.

Remote sensing (RS) and Geographic Information System (GIS) analytical techniques facilitated the analysis of changes in the environment of the study area through time. The information on land cover that they generate, together with the experience of the people whose livelihoods depend on the forest, can be utilized in assessing policies on forest use and protection implemented in the area of interest. As this study shows, RS and GIS methodologies can contribute to this purpose by providing reliable information on forest cover changes.

Subject Index : Remote sensing, Forest influences