Hosted/UNCCD_CBD_drylands2007 (FeatureServer)

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UNCCD_CBD_001_drylands2007 (3)

Description: <DIV STYLE="text-align:Left;"><DIV><DIV>The original dataset developed by the MA is a subset of the aridity zone map created by CRU/UEA, UNEP/GRID for the World Atlas of Desertification. Aridity zones were derived from an Aridity Index (AI) which is calculated as the ratio of precipitation to potential evapotranspiration. Zones included in this dataset are: hyperarid, arid, semiarid, and dry subhumid. These are in accordance with the United Nations Convention to Combat Desertification (UNCCD) definition of Drylands. In the first instance, we compared the map published by Miles et al (2006) to show global distribution of tropical dry forests with the dryland map produced by Sörensen (2007). The dry forest areas were almost entirely included within the areas originally mapped as drylands. The only exception were some seasonally dry forests of continental southeast Asia, but these are climatically relatively moist, being mostly characterised by P/PET ratios well above 0.65 and having few other dryland features.In a second approach we reviewed the WWF ecoregions dataset. Sörensen (2007) had identified a number of additional ecoregions for possible inclusion. Based on expert knowledge, this resulted in the inclusion of the 13 additional ecoregions most likely to include dryland features and/or dry and subhumid tropical forests. (Table 1).<TABLE><TBODY><TR><TD>Table 1. Ecoregions included in dryland area following review</TD></TR><TR><TD>Selenge-Orkhon forest steppe</TD></TR><TR><TD>Tian Shan montane steppe and meadows</TD></TR><TR><TD>Northwestern Himalayan alpine shrub and meadows</TD></TR><TR><TD>Central Tibetan Plateau alpine steppe</TD></TR><TR><TD>Southeast Tibet shrublands and meadows</TD></TR><TR><TD>Pamir alpine desert and tundra</TD></TR><TR><TD>Yarlung Tsangpo arid steppe</TD></TR><TR><TD>Hawaii tropical low shrublands</TD></TR><TR><TD>North Tibetan Plateau-Kunlun Mountains alpine desert</TD></TR><TR><TD>Hawaii tropical high shrublands</TD></TR><TR><TD>Maputaland-Pondoland bushland and thickets</TD></TR><TR><TD>Ascension scrub and grasslands</TD></TR><TR><TD>Drakensberg alti-montane grasslands and woodlands</TD></TR></TBODY></TABLE></DIV></DIV></DIV>

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Copyright Text: References: Miles, L., A.C. Newton, R.S. DeFries, C. Ravilious, I. May, S. Blyth, V. Kapos and J.E. Gordon. (2006). A global overview of the conservation status of tropical dry forests. J. Biogeogr. 33: 491–505. Sorensen, L. (2007). A spatial analysis approach to the global delineation of dryland areas of relevance to the CBD Programme of Work on Dry and Subhumid Lands. UNEP-WCMC, Cambridge. Full citation: UNEP-WCMC. (2007). A spatial analysis approach to the global delineation of dryland areas of relevance to the CBD Programme of Work on Dry and Subhumid Lands. Dataset based on spatial analysis between WWF terrestrial ecoregions (WWF-US, 2004) and aridity zones (CRU/UEA; UNEPGRID, 1991). Dataset checked and refined to remove many gaps, overlaps and slivers (July 2014). Cambridge (UK): UNEP-WCMC.

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