Quantitative landscape management targets for biodiversity conservation: Method development with an example from the Philippines

Like many other parts of the tropics, the Philippines are facing a biodiversity crisis, with extensive deforestation driving species extinctions. In many cases, these extinctions can be averted by site level strategies – protecting the key biodiversity areas where threatened species occur. However, some threatened species require large areas of landscape. Here, we develop a method for identifying landscape level conservation targets, and set an example with a case study of an area-demanding threatened species, the Philippine Eagle (Pithecophaga jefferyi). We use the criteria under which the species is evaluated on the IUCN Red List to derive spatially explicit targets. This strategy reveals that land management modifications to allow the recovery of the species’ populations to maximum population density and occupancy throughout suitable habitat in Eastern Mindanao (11,346 km²) or the Sierra Madre (13,786 km²) would be just sufficient for it to be downlisted from the threatened categories of the IUCN Red List. Further work is necessary to develop equivalent methods for targeting other ecological processes on which threatened species depend, for landscape level adaptation to climate change, and for optimizing land use planning to deliver socio-economic benefits without compromising biodiversity. Nevertheless, the techniques developed here should allow explicit, justifiable targeting of landscape management and conservation of biodiversity in the Philippines and beyond.