Within the watershed of Manila Bay upland forests abound which are sources of food, timber, fuel wood and other products, as well as habitats for wildlife. These forests provide protection from soil erosion and help maintain the water levels and water quality in rivers and streams. Mount Makiling, Angat Dam watershed, La Mesa Dam watershed, Mounts Palay-Palay / Mataas na Gulod Protected Landscape, Mount Arayat and other portions of national parks located in Bataan, Bulacan, Rizal and Tarlac form part of these upland forest ecosystem.