Global-scale patterns of forest fragmentation

We report an analysis of forest fragmentation based on l-km resolution land-cover maps for the globe. Measurements in analysis windows from 81 km (2) (9 x 9 pixels, "small" scale) to 59,049 km (2) (243 x 243 pixels, "large" scale) were used to characterize the fragmentation around each forested pixel. We identified six categories of fragmentation (interior, perforated, edge, transitional, patch, and undetermined) from the amount of forest and its occurrence as adjacent forest pixels. Interior forest exists only at relatively small scales; at larger scales, forests are dominated by edge and patch conditions. At the smallest scale, there were significant differences in fragmentation among continents; within continents, there were significant differences among individual forest types. Tropical rain forest fragmentation was most severe in North America and least severe in Europe-Asia. Forest types with a high percentage of perforated conditions were mainly in North America (five types) and Europe-Asia (four types), in both temperate and subtropical regions. Transitional and patch conditions were most common in 11 types, of which only a few would be considered as "naturally patchy" (e.g., dry woodland). The five forest types with the highest percentage of interior conditions were in North America; in decreasing order, they were cool rain forest, coniferous, conifer boreal, cool mixed, and cool broadleaf.