|
Monitoring Changes in the Philippine Vegetation Cover from 2000 to 2011
Gay Jane
P.
Perez, NASA/GSFC Hydrospheric and Biospheric Sciences Laboratory, gay.j.perez@nasa.gov
(Presenter)
The Philippines is among the top ten countries in the world with high deforestation rate, with 9.8 million hectares (M Ha) of forest lost from 1934 to 1988. The remaining forest cover, as estimated in 2003, is only 7.2 M Ha, which comprises 24% of the total Philippine land area. A major cause of deforestation is the conversion of these lands to agricultural farms and residential areas. In 2002, the Philippines registered a total of 4.8 million agricultural farms (covering 9.7 M Ha), which constituted 32.2% of the country’s total land area. To evaluate the effectiveness of Philippine vegetation as a sink for Carbon Dioxide it is important to have an updated inventory of land cover types including existing forested and other vegetation areas. However, much of the currently available data are field measurements with incomplete historical records and sparse spatial coverage. To overcome this limitation, we analyzed Normalized Difference Vegetation Indexes (NDVI) satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS) to establish the state of the vegetation in the country and determine how it has been changing during the last decade. Using 16-day composites of NDVI at 250 m spatial resolution, we create time-series plots over the course of eleven years. Large seasonal and interannual variability were observed reflecting the differences in the type of vegetation in different parts of the country. NDVI maxima are observed during the months of August to October with moderate interannual variability while NDVI minima are recorded in the summer months (May to June) with much stronger interannual variability. The lowest value of NDVI from 2000 to the present was observed in the summer of 2010, with a decline of 5% from the previous year compared to an average fluctuation of 2%. This event coincided with an anomalously warm and exceptionally dry year in 2010. Most of the areas that showed significant decline in vegetation in the summer are agricultural lands, which exhibit well-defined seasonality that coincides with the cropping period, while known forested areas showed little or insignificant changes in vegetation. We use this seasonality information from NDVI measurements to classify major types of vegetation and identify crops with distinctive cropping period. High-resolution satellite data from LANDSAT and PALSAR were used in conjunction with field measurements to confirm the validity of such a classification scheme. Presentation Type: Poster Session: Global Change Impact & Vulnerability (Tue 11:30 AM) Associated Project(s):
Poster Location ID: 302
|