Citation
Miles, L., Newton, A.C., DeFries, R.S., Ravilious, C., May, I., Blyth, S., Kapos, V., Gordon, J.E. (2006). A global overview of the conservation status of tropical dry forests. Journal of Biogeography. 33(3): 491-505. https://doi.org/10.1111/j.1365-2699.2005.01424.x
The global biogeographic classification presented by Olson et al. (2001) was used to identify biomes relevant to tropical dry forests. These were subsequently overlayed with a map of current (at the time of publication) forest cover derived from the MODIS Vegetation Continuous Fields (VCF) product (Hansen et al., 2003), which depicts percentage tree cover at a resolution of 500m.
To produce the distribution map, tropical forest was defined as those tropical grid cells with at least 40% forest cover, based on the MODIS data set, which uses a 500-m equivalent grid in geographic projection (Hansen et al., 2002, Hansen et al., 2003). Then, dry and seasonally dry forest was defined by further limiting this distribution to (1) cells found within the ‘Tropical and subtropical dry broadleaf forest’, ‘Mediterranean forest, woodland and scrub’, or ‘Desert and xeric shrubland’ biomes of the WWF ecoregions data set (Olson et al., 2001); and (2) cells falling within a subset of the ‘Tropical and subtropical grassland, savanna and shrub’ biome (limited to areas falling within the aridity zones from the World Atlas of Desertification (Middleton et al., 1997) to exclude this category's more humid subtypes).
This map represents the estimated maximum distribution of tropical dry and seasonally dry forest. It has not been ground-truthed, and it is particularly important to note that the definition of ‘forest’ is restricted to areas with 40% tree cover or greater. The 40% value corresponds to the FAO Global Forest Resources Assessment definition of closed forest (FAO, 2001).
This dataset was used in the publication " A global overview of the conservation status of tropical dry forests, 2006. Miles, L., Newton, A., DeFries, R., Ravilious, C., May, I., Blyth, S. Kapos, V. and Gordon, J. Journal of Biogeography 33: 491-505. The aim of this paper was to analyse the conservation status of tropical dry forests at the global scale, by combining a newly developed global distribution map with spatial data describing different threats, and to identify the relative exposure of different forests to such threats. References: Hansen, M.C., DeFries, R.S., Townshend, J.R.G., Carroll, M.,Dimiceli, C. & Sohlberg, R.A. (2003) Global percent treecover at a spatial resolution of 500 meters: first results of theMODIS Vegetation Continuous Fields algorithm. EarthInteractions, 7, 1–15. Middleton, N.J. & Thomas, D.S.G. (1997) World atlas of desertification. United Nations Environment Programme/Edward Arnold, London. Olson, D.M., Dinerstein, E., Wikramanayake, E.D., Burgess,N.D., Powell, G.V.N., Underwood, E.C., D’Amico, J.A.,Itoua, I., Strand, H.E., Morrison, J.C., Loucks, C.J., Allnutt,T.F., Ricketts, T.H., Kura, Y., Lamoreux, J.F., Wettengel,W.W., Hedao, P. & Kassem, K.R. (2001) Terrestrial ecoregions of the world: a new map of life on Earth. BioScience,51, 933–938.