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The Holdridge Life Zones data set is from the International Institute for Applied Systems Analyses (IIASA) in Laxenburg, Austria. The data set shows the Holdridge Life Zones of the World, a combination of climate and vegetation (ecological) types, under current, so-called "normal" climate conditions, as well as under a presumed doubling of atmospheric CO2. The Life Zones were devised using three indicators: biotemperature (based on the growing season length and temperature); mean annual precipitation; and a potential evapotranspiration ratio, linking biotemperature with annual precipitation to define humidity provinces. The data set has a spatial resolution of one-half degree latitude/longitude, and a total of 38 life-zone classes which are listed on the accompanying legend sheet.
The Holdridge Life Zones data set includes a total of four data files. The first (HOLDNORM) is as described in the paragraph above; the second (HOLDDOUB) shows how the Life Zones would change given an assumed doubling of atmospheric CO2 (according to a General Circulation Model from the U.K. Office of Meteorology). The third and fourth data files show only those portions of the Life Zones which would undergo changes, that is for both the old classification (HOLDCHFR) before and the new classification (HOLDCHTO) after the theoretical doubling of CO2 (in effect, these areas have the appearance of 'sliver' polygons). The data set is useful for testing the role of climate influence on vegetation patterns, and also as a basis for evaluating future effects of climate change on vegetation.
The Holdridge Life Zones data file consists of 360 rows (lines) by 720 columns (elements/pixels/samples) of data, and one byte/eight bits per pixel. Its origin is at 90 degrees North latitude and 180 degrees West longitude, and it covers the entire globe to 90 degrees South latitude and 180 degrees East longitude. At one-half degree spatial resolution, each data file comprises 259.2 kilobytes, and thus all four data files described above together equal 1.04 Mb.
The proper reference to this data set is "Leemans, Rik, 1990. Global data sets collected and compiled by the Biosphere Project, Working Paper, IIASA-Laxenburg, Austria." Another useful description of this data set is found in the March 1990 issue of the IIASA publication known as 'Options', in an article entitled "IIASA's Climate Database" (pages 9-12). The source of this GRID-held data set is IIASA.
GRID LEGEND FOR HOLDRIDGE LIFE ZONES OF THE WORLD (Leemans, 1989) *
Class no. Life Zone title _________ _______________
1 Polar desert 2 Subpolar dry tundra 3 Subpolar moist tundra 4 Subpolar wet tundra 5 Subpolar rain tundra 6 Boreal desert 7 Boreal dry scrub 8 Boreal moist forest 9 Boreal wet forest 10 Boreal rain forest 11 Cool temperate desert 12 Cool temperate desert scrub 13 Cool temperate steppe 14 Cool temperate moist forest 15 Cool temperate wet forest 16 Cool temperate rain forest 17 Warm temperate desert 18 Warm temperate desert scrub 19 Warm temperate thorn scrub 20 Warm temperate dry forest 21 Warm temperate moist forest 22 Warm temperate wet forest 23 Warm temperate rain forest 24 Subtropical desert 25 Subtropical desert scrub 26 Subtropical thorn woodland 27 Subtropical dry forest 28 Subtropical moist forest 29 Subtropical wet forest 30 Subtropical rain forest 31 Tropical desert 32 Tropical desert scrub 33 Tropical thorn woodland 34 Tropical very dry forest 35 Tropical dry forest 36 Tropical moist forest 37 Tropical wet forest 38 Tropical rain forest
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