Global Vegetation and Land Use: New High-Resolution Data Bases for Climate Studies

Abstract

Global vegetation and land-use data bases (1° latitude by 1° longitude resolution), designed for use in studies of climate and climate change, were compiled in digital form drawing upon approximately 100 published sources complemented by a large collection of satellite imagery. The vegetation data were encoded using the UNESCO classification system; land-use data were encoded using a classification system developed by the author. The vegetation and land-use data were then integrated into a land-cover data base. Areal estimates for most ecosystems from the land-cover data base were found to be significantly different from areal estimates derived from two other global land-cover sources. Possible explanations for discrepancies among these data bases include differences in ecosystem definitions and source material used in compilation. From areal estimates of major ecosystems, derived from the new vegetation and land-cover data bases it is estimated that the total ecosystem reduction caused by agricultural activities amounts to 17.6 × 10⁶ km² globally, with the greatest reduction occurring in non-tropical forests. Extensive subsistence agriculture which remains largely unreported in crop inventories accounts for 2.6 × 10⁶ km² of this figure, with the balance of 15 × 10⁶ km² agreeing encouragingly well with FAO's (1980) reported global crop area of 14.5 × 10⁶ km². As an example of the flexibility of the new data base, areal estimates and brief definitions of selected ecosystem subdivisions are presented for the world and mapped for North America.