This study demonstrates the use of TARGET (software) trade-offs analysis for prioritizing environmental service payments (PSA or ‘Pagos por Servicios Ambientales' in Spanish) to private land-owners in the Osa Conservation Area (ACOSA), Costa Rica. The paper answers a number of research questions of direct management relevance in ACOSA and general relevance to biodiversity conservation planning in the region. The analyses for the ACOSA area conclude that the 1999-2001 selection of areas to receive environmental service payments for forest protection, forest management, and reforestation was not cost-efficient, in the sense of maximizing biodiversity protection on private land outside existing national parks, while also minimizing the opportunity costs to agriculture and commercial forestry. The study goes on to show how TARGET methodology may be used to rank PSA candidate areas by their cost-efficiency in representing complementary biodiversity at lowest cost at regional level (ACOSA).
