Focal Nodes Identification Using Habitat Availability Concept for Simulation of Ecological Connectivity Network of Quezon City, Philippines

Abstract

Anthropocentric orientation of urban development processes leads to deficiency of areas with significant environmental values in the urban landscapes. As landscape planners try to increase the quality of living in the urban environment, efforts are focused only on the hot spots which often cater only to the recreational needs of urban dwellers. In Quezon City, the local government unit plans to create the Green Lung Network featuring a chain of developments linking La Mesa Nature Reserve, the largest green space in Metro Manila, to all the open spaces and parks in the city. However, the chosen areas to be connected are based only on area size of green spaces and opportunities for economic development. To support and enhance the connectivity plan of the city government, this study aims to identify the focal nodes which represent the key habitat patches of interest on the landscape between which flows are modelled in circuit analysis for simulating an ecological connectivity network. Parameters are based on empirical habitat-use data on the preference of biological indicators/focal species. For computational feasibility, instead of treating every occurrence of suitable habitat on the landscape as a focal node, this study applies the Habitat Availability (reachability) concept using the GIS tool Conefor Sensinode. This allows ranking habitat patches (patches prioritization) by their contribution to landscape connectivity, which provides objective criteria for the selection of the most critical habitat areas for conservation planning purposes. Not only the spatial arrangement of the habitat is considered (structural connectivity), but also the dispersal distances and the behavioural response of species to the physical structure of the landscape (functional connectivity) is taken into account in the analysis. The results revealed that focal nodes of Quezon City include not only the ecological cores but also other tiny patches of green spaces. Moreover, a more surprising result is that some highly vegetated nodes did not qualify as priority nodes for conservation.