The importance of forest fragments for birds and local communities in Northeast Luzon, Philippines

The Philippine islands used to be covered mainly with forest until recent times. Within evolutionary history, the vast majority of flora and fauna species now occurring in the Philippines, colonized or evolved in forest habitats and not in cleared areas. Because of its specific island biogeographical history, the Philippines has a very high number of endemic species. During the last 100 years, most of the original tropical forests in the Philippines have been removed for timber or cleared for crop cultivation. The forest fragments that still remain, usually in areas not suitable for cultivation or timber extraction, harbor remnants of the biodiversity originally found in extensive lowland forest. The species richness of forest fragments is expected to be correlated to fragment size and the distance of the fragments to remaining forest. Local communities often depend on these fragments for their supply of a variety of forest products. We studied forest fragments in the Cagayan Valley of Northeast Luzon. One series of studies aimed to describe the vegetation of forest patches. We found that many patches retain some of the tree species usually found in primary forest. Gallery forests along creeks have higher tree to shrub ratios than woody patches surrounded by grassland. Another series of studies aimed to describe the utilization of forest products by local communities. We found that a variety of "free access" products were derived from forest patches, the most important being fuelwood. Rural and even urban communities in NE Luzon still depend, to a large extent, on the use of fuelwood and the forest patches play a crucial role in providing that. Last, a study was conducted on avian species richness in forest patches in relation to patch size and distance to contiguous remnant forest, of which a large stretch is present in the Sierra Madre Mountains. Species richness and the proportion of endemic species were found to be related to patch size but not so much to distance to remnant forest. Two forest plots, one degraded and the other slightly disturbed, which were surveyed in remnant forest in the Sierra Madre under similar conditions were compared. Avian species richness was higher in the degraded forest plot but the absolute and relative numbers of endemic species were higher in the slightly disturbed plot. Therefore, we conclude that forest structure is an important factor which determines the suitability of forest habitat for several endemic bird species. The dual role of forest fragments as a habitat for Philippine bird species and as a resource of multiple products and services to local communities offers possibilities for community-based conservation activities, though specialized endemic bird species will probably not survive if larger well-protected forest areas disappear.