Global Tree Cover
| Analytical Overview |
| The percent tree cover map was developed by researchers at the University of Maryland (UMD). They applied a linear mixture model to 1-km AVHRR data to estimate proportional land cover for various vegetation characteristics, such as woody or shrubby vegetation, evergreen or deciduous leaf type, and bare ground (DeFries et al., 2000). The methodology used to develop this map does not set minimum thresholds of tree cover within each cell, since the purpose is not to define "forest" but to identify where trees are present. This satellite-based percent tree cover map cannot readily be compared with that of the IGBP, because it defines tree cover by means of fewer parameters (percent tree cover and vegetation height). |
Map Projection
Interrupted Goode's Homolosine
Map Description
This map presents an alternative view of the world’s tree cover. It illustrates global cover of woody vegetation, on a continuous scale from 0 to 100 percent. Woody vegetation is defined as mature vegetation whose approximate height is greater than five meters and can thus be equated with trees. This technique avoids the problems inherent in traditional classification schemes (like that of the IGBP) with discrete numbers of vegetation types. The use of such classification schemes introduces abrupt boundaries and unrealistic homogeneity into the depiction of land cover types that are, in practice, often finely graded and heterogeneous. The percent tree cover map helps to identify areas of partial tree cover that, while not formally classified as forest, nevertheless provide many of the same goods and services, especially food, fuelwood, habitat, and soil protection. These areas are vulnerable to clearance, because they receive less attention and formal protection than forests.
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Citation:
World Resources Institute - PAGE, 2000
Sources:
- Defries, R.S., M.C. Hansen, J.R.G. Townshend, A.C,. 2000. A new global 1-km data set of percentage tree cover derived from remote sensing..Global Change Biology6: