378 BIOTROPICA 33(3): 378–384 2001 Deforestation in Costa Rica: A Quantitative Analysis Using Remote Sensing Imagery 1 G. Arturo Sa ´ nchez-Azofeifa 2 Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada Robert C. Harriss National Center for Atmospheric Research, P.O. Box 3000, Boulder, Colorado 80307-3000, U.S.A. and David L. Skole Department of Geography, Michigan State University, East Lansing, Michigan 48824, U.S.A. ABSTRACT Accurate estimates of forest cover and forest fragmentation are critical for developing countries such as Costa Rica, which holds four to five percent of the world’s plant and bird species. We estimated forest cover for Costa Rica using Landsat 5 Thematic Mapper satellite scenes acquired between 1986 and 1991. In 1991, 29 percent (ca 14,000 km 2 ) of the land cover of Costa Rica was closed forest cover; of that forested area, ca 30 percent is protected by national conservation policies. Forest loss in a study area representing ca 50 percent of Costa Rica’s territory during a five-year period (1986–1991) was 2250 km 2 , and the estimated deforestation rate was ca 450 km 2 /yr, or ca 4.2 percent/yr, of remaining forest cover. Forests are almost completely eliminated from the Tropical Moist Forest and Premontane Moist Forest life zones, and the level of fragmentation of remaining forests may be more advanced than previously thought. RESUMEN La obtencio ´n de estimaciones precisas de la cobertura forestal y su nivel de fragmentacio ´n es crı ´tica para la conservacio ´n de la biodiversidad. Costa Rica contiene en su territorio nacional entre el cuatro y cinco por ciento de todas las especies de plantas y aves del mundo. Este estudio provee una estimacio ´n precisa de la cobertura nacional forestal del paı ´s y su distribucio ´n a nivel ecolo ´gico basada en ima ´genes de sate ´lite adquiridas entre 1986 y 1991 por el Trazador Tema ´tico Landsat 5. Para 1991, el paı ´s tenı ´a una cobertura forestal de bosque perennifolio del 29 por ciento (ca 14,000 km 2 ); el 71 por ciento de este bosque carecı ´a de proteccio ´n mientras que el 29 por ciento restante esta ´ protegido por el Sistema Nacional de A ´ reas de Conservacio ´n. La pe ´rdida total de bosque en el a ´rea de estudio, durante un perı ´odo de cinco an ˜os (1986–1991) y la cual representa ca 50 por ciento del territorio nacional, fue de 2250 km 2 . La tasa de deforestacio ´n estimada es de ca 450 km 2 por an ˜o, o ca 4.2 por ciento anual. El proceso de deforestacio ´n tropical ha eliminado casi completamente los bosques hu ´medo tropical y hu ´medo premontano del paı ´s. Los resultados de este trabajo sugieren que el nivel de fragmentacio ´n de los bosques costarricenses puede ser ma ´s grande de lo que se habı ´a pensado. Key words: Costa Rica; habitat fragmentation; tropical deforestation. THE TRANSFORMATION AND DEGRADATION OF TROPI- CAL FORESTS represent the primary driving force in the loss of biological diversity worldwide. Impacts and consequences of deforestation also extend far beyond the boundaries of transformed land (Vitou- sek 1994, Vitousek et al. 1997). Tropical forests are intimately linked to climate system dynamics, atmospheric composition, and other ecosystem ser- vices that contribute to human welfare and the sus- tainability of the earth’s life-support system (Daily 1 Received 24 January 2000; accepted 23 August 2000. 2 Corresponding author. E-mail: arturo.sanchez@ ualberta.ca & Ehrlich 1992, Daily 1997). The challenge of seeking a balance between an undisturbed nature and the human domination of ecosystems in trop- ical regions will be increasingly contentious at the turn of the 21st century due to population growth and the need for improved socioeconomic welfare. Costa Rica is often hailed as a model for how developing nations can balance the conservation of nature and economic development. The govern- ment has set aside almost one-fourth of the nation’s land for conservation and has been active in dis- cussions on the uses of protected areas for biodi- versity inventory, ecotourism, carbon sequestration, and bio-prospecting for medicines (Quesada-Mateo