Understanding IUCN protected area categories

Protected areas are the primary tool for in situ biodiversity conservation across the world. The system of protected area management categories defined and monitored by the World Conservation Union (IUCN) currently sets the standard for internationally recognized protected area management. IUCN unveiled this system in 1978 and revised it in 1994. The current system of categories reflects a dramatically increased degree of human inhabitation and resource use in protected areas. We trace the history of efforts to categorize protected area management objectives and document a clear trend toward increasing human presence in them. Analyzing available data from the period 1990-2003, we test the hypothesis that the relative coverage of uninhabited areas has decreased over time. Contrary to our expectations, uninhabited protected areas (category la) have actually increased both absolutely and relative to potentially inhabited protected areas. In 1990, category I protected areas covered 507,908 km(2) and comprised 7.8% of category I-V areas. By 2003, category la protected areas covered 1,033,888 km(2) and comprised 9.6% of category I-V areas. Unfortunately, limitations in the availability of historical data that describe protected area coverage by both region and category constrain our ability to explain this trend. Furthermore, the process of assigning categories to protected areas is not transparent and may be prone to incorrect categorization.