This indicator measures the total dryland area (in sq. km) that can be defined as additional dryland area, in a given country.
Additional drylands areas include areas that might not fall - based on the ratio of precipitation to potential evapotranspiration (P/PET) - within the intervals traditionally used to identify arid (0.06 - 0.20 P/PET), semiarid (0.21 - 0.50 P/PET) and subhumid areas (0.51 - 0.65 P/PET).
Based on expert knowledge, the following ecoregions are likely to include dryland and dry-subhumid features:
- Selenge-Orkhon forest steppe
- Tian Shan montane steppe and meadows
- Northwestern Himalayan alpine shrub and meadows
- Central Tibetan Plateau alpine steppe
- Southeast Tibet shrublands and meadows
- Pamir alpine desert and tundra
- Yarlung Tsangpo arid steppe
- Hawaii tropical low shrublands
- North Tibetan Plateau-Kunlun Mountains alpine desert
- Hawaii tropical high shrublands,
- Maputaland-Pondoland bushland and thickets
- Ascension scrub and grasslands
- Drakensberg alti-montane grasslands and woodlands
The values of this indicator have been aggregated at the country level by ILRI, in collaboration with the ILC's Rangelands initiative, based on:
- 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).