Changes in the landscape pattern of the La Mesa Watershed – The last ecological frontier of Metro Manila, Philippines

The La Mesa Watershed (LMW) is considered as the ‘lungs’ and the last ecological frontier of the Philippines’ National Capital Region, Metro Manila. It is among the many watersheds in the country that suffered from severe deforestation in the past. Nevertheless, over the past few decades, reforestation programs for the LMW have also been initiated. The spatiotemporal monitoring of landscape pattern (composition and configuration) is needed to inform policy and support forward-looking management planning toward landscape sustainability. However, the changes in the landscape pattern of the LMW, including the extent of forest cover loss and gain over the past decades, have not been quantified; hence, this study. We used remote sensing data (Landsat) to classify the land use/land cover of the LMW in 1988, 2002 and 2016. We subsequently used spatial metrics to quantify the changes in the landscape pattern of the watershed. We found that between 1988 and 2002, a period that largely preceded the start of the LMW's major rehabilitation (c. 1999), the watershed had a net forest cover loss of 259 ha. From 2002 to 2016, it had a net forest cover gain of 557 ha. The detected increase in forest cover was supported by the percent tree cover change analysis results based on MODIS data. The deforestation of the LMW resulted in landscape fragmentation as indicated by the decrease in the area of forest and mean forest patch size, and the increase in forest patch density, etc. Forest restoration activities have helped improve the watershed's landscape connectivity as signified by the increase in the area of forest and mean forest patch size, and the decrease in forest patch density, etc. The results also revealed that rapid urbanization has been a major factor driving landscape changes around the LMW, and this requires proactive, forward-looking management planning. Overall, the LMW's case presents some valuable learning experience and insights regarding public-private partnerships toward watershed and forest-related rehabilitation initiatives. On a national scale, the Philippine government has embarked on a massive national greening program. The findings of this study suggest that such efforts could lead to the enhancement of denuded forest areas, if done properly.