Love A. Pannguiton, Royce G. Eustaquio, Paolo Campo
Department of Geodetic Engineering
University of the Philippines in Diliman
1101 Quezon City, Philippines
Tel: (632)- 920-53-01 local 5534
This paper aims to investigate the capability of integrating images from a multisensor platform in detecting urban sprawl in the forest reserved area. Using Remote sensing (RS) and Geographic Information System (GIS0 technologies, it attempts to monitor and study development changes occurring in the Mount makiling Forest Reserve (MFR) over the years. Visual interpretation of available imageries such as SPOT, Landsat TM ands TOPSAR acquired over different periods can produce a land use map of forest encroachment in the area as well as identification of possible hazard-risk areas of settlements .
Supplementary observations such as ground truthing using Global Positioning System (GPS) were done to reinforce the data analysis. The digitized boundary of the reserve was inputted to strengthen the assessment and analysis of the trend and behavior of these settlements vis-a-vis the forrest reserve.
Economic opportunities as well as the excellent venue for settlement area are two factors that trigger the increase in in-migration of the population in the area . In 1991 alone , 71% of the total households residing in the MFR are migrants (Torres & Rebugio 1991). Given the demand for housing space, construction of low cost housing has sprouted in the area. As sporadic mushrooming of settlements continue to intensify around the fringes of Mount Makiling. Its forest cover is constantly being threatened by the growing problems of pollution, land conversion and improper waste management . with the limited space for residential expansion, the areas surrounding the foot of Mount Makiling have become the ultimate catchments of these settlements. The encroachment level that initial signs of slope deterioration can be observed in some areas.
The declaration of the Mount Makiling Forest Reserve (MFR) as a national park has slowed down the expansion of the these settlements in the area. Somehow, because of the vastness of the area, and lack the of a clear government policy in dealing with the occupants, communities near the fringes have slowly , but steadily, encroached upon the reserve area.
The Study Area
The makiling Forest Reserve , with an area of 4244 hectares, is located within Mount Makiling at latitude 14°8′ N and longitude 121°11’E. it lies within 65 kilometers of Metro Manila, and is bounded by four municipalities, namely, Los Banos Bay and Calamba in the province of Laguna, and Sto. Tomas located in province of Batangas.
The Makiling Forest Reserve (MFR) was established in 1910. then in 1920 it was declared as a National Botanic Garden. In 1960, the administration of the reserve was transferred to the University of the Philippines and in 1996 the College of Forestry became the lead entity in implementing the FMR Master Plan.
The MFR also serves as a watershed, a geothermal resource and a gene pool of biological diversity. Settlements within the reserve also used portions of the MFR for economic reasons such as cutflower and ornamental farming.
Issues and Concerns
Through the years, the MFR has been surrounded by growing settlements whose influence constantly threatens the resources of the reserve. There has been difficulty monitoring the extent and rapidity of the changes occurring within the reserve itself. Various problems such as forest encroachment, logging , kaingin, pollution, poaching of forest products, uncontrolled in -migration, and increase in population endangering the stability and sustainability of the forest resource. Other problems like indiscriminate land conversion to non-agricultural use and infrastructure built-up are a common scene in its periphery.
The study uses the Landsat TM (1992), SPOT images (1993) and the radar image (TOPSAR) of the area taken 1996. Ancillary data such as the NAMRIA’s topographic maps (scale of 1:50,000) were used for images rectification of the SPOT data. All images were rectified and enhanced using standard operating techniques for the preparation of the analysis.
A supervised classification was performed on the images with the following land use classes;
- cultivated/cleared area
- settlements and special uses
- water body
The use of the existing land use map of the area in vector format is also integrated particularly the vales of different allocation of use. This will be compared and evaluated to the values generated by images classification.
Discussion of Results
Lansat TM images (19920 was first evaluated and compared to the existing land use map of 1991. Encroachment of small area sin the reserve periphery was detected. From the SPOT (1993). Patches of settlements denoted by pinkish in color begin to cluster near the urban canters. Small clearings can also be noted on some portion of the forest slopes . some areas, which were grasslands prior to 1993 have been converted into forest plantations. Vegetation in areas near the peak already have signs of unhealthy trees can be observed near the fringes and in deep slopes.
Since both images (Landsat TM and SPOT ) cannot fairly exhibits slope deterioration the use of the radar image (TOPSAR) was analyzed, and observed some changes near the mouth of the drainage system.
An analysis of ht image classification results differed considerably because of the length of period these images were taken. The settlement pattern in the reserve appears to length of period these images were taken. The settlement pattern in the reserve appears to exhibit an irregular behavior near the fringes of the reserve. Areas of settlements near the roads have experienced changes, more particularly converted to industrial use, compared to other areas in the reserve .
Road improvements projects being undertaken by local government units surrounding the reserve lave the was for real-estate firms to develop the area into housing subdivisions. Notable changes were detected with in area inside the reserve. Small-scale developments such as upland and recreation parks and continue to flourish.
The major changes that were observed mostly were areas formerly occupied by grasses being converted into residential use. These developments can be observed near the areas with steeper slopes especially adjoining the main thoroughfare. Other changes detected were conversion from forest to agricultural use. There are some areas where developments were reversed; i.e from cultivated to grassland, and from grassland to forest plantation. This can be denoted by roads being closed for public use as well as reforestation.
The integration of various images to detect settlement intrusion in the forest reserve areas is possible and yields fair results . changes detection is significantly improved image-fusion and GIS technologies. This approach is a very helpful tool in decision support system and for urban growth management.
The authors would like to acknowledge the following entities for the fulfillment of this paper.
- Lillesand and Kiefer (1994) Remote Sensing and Image Interpretation, 3rd ed. Wiley, New York, 743 pp.
- Cruz, R.V., et Al., 1991 Agrosystem Analysis of Makiling Forest Reserve, UP Los Banos, Laguna
- Torres, C.S. and E.N. Rebugio 1991 Census of household Occupants in Makiling Forest Reserve, UP Los Banos, Laguna.