The Holdridge life zones system is a global bioclimatic scheme for the classification of land areas. It was first published by
Leslie Holdridge
Leslie Ransselaer Holdridge (September 29, 1907 – June 19, 1999) was an Americans, American botany, botanist and climatology, climatologist. He was the father of composer Lee Holdridge as well as the father of Leslie A. Holdridge, Lorena Holdri ...
in 1947, and updated in 1967. It is a relatively simple system based on few empirical data, giving objective criteria. A basic assumption of the system is that both
soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
and the
climax vegetation
In scientific ecology, climax community or climatic climax community is a historic term for a community of plants, animals, and fungi which, through the process of ecological succession in the development of vegetation in an area over time, hav ...
can be mapped once the climate is known.
Scheme
While it was first designed for tropical and subtropical areas, the system now applies globally. The system has been shown to fit not just
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
vegetation zones,but
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...
zones, and
boreal
Boreal may refer to:
Climatology and geography
*Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch
*Boreal climate, a climate characterized by long winters and short, cool to mild ...
zones too, but is less applicable to cold oceanic or cold arid climates where moisture becomes the predominant factor. The system has found a major use in assessing the potential changes in natural vegetation patterns due to
global warming
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
.
The three major axes of the
barycentric subdivision
In mathematics, the barycentric subdivision is a standard way to subdivide a given simplex into smaller ones. Its extension on simplicial complexes is a canonical method to refine them. Therefore, the barycentric subdivision is an important tool i ...
s are:
*
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
(annual, logarithmic)
* bio
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
(mean annual, logarithmic)
*
potential evapotranspiration
Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpira ...
ratio (PET) to mean total annual
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
.
Further indicators incorporated into the system are:
*
humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.
Humidity depe ...
provinces
*
latitudinal regions
*
altitudinal belts
Biotemperature is based on the growing season length and temperature. It is measured as the mean of all annual temperatures, with all temperatures below freezing and above 30 °C adjusted to 0 °C, as most plants are dormant at these temperatures. Holdridge's system uses biotemperature first, rather than the temperate latitude bias of
Merriam's life zones, and does not primarily consider elevation directly. The system is considered more appropriate for
tropical vegetation
Tropical vegetation is any vegetation in tropical latitudes. Plant life that occurs in climates that are warm year-round is in general more biologically diverse that in other latitudes. Some tropical areas may receive abundant rain the whole ye ...
than Merriam's system.
Scientific relationship between the 3 axes and 3 indicators
Potential evapotranspiration
Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpira ...
(PET) is the amount of water that would be evaporated and transpired if there were enough
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
available. Higher temperatures result in higher PET.
Evapotranspiration
Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpi ...
(ET) is the raw sum of evaporation and plant transpiration from the Earth's land surface to atmosphere. Evapotranspiration can never be greater than PET. The ratio, Precipitation/PET, is the
aridity index
An aridity index (AI) is a numerical indicator of the degree of dryness of the climate at a given location. A number of aridity indices have been proposed (see below); these indicators serve to identify, locate or delimit regions that suffer from ...
(AI), with an AI<0.2 indicating
arid/hyperarid, and AI<0.5 indicating dry.
Coldest
/\
/ \
PET - -- - Rain
The coldest regions have not much evapotranspiration nor precipitation as there is not enough heat to
evaporate
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
much water, hence
polar deserts. In the warmer regions, there are deserts with maximum PET but low rainfall that make the soil even drier, and rain forests with low PET and maximum rainfall causing
river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
systems to drain excess water into oceans.
Classes
All the classes defined within the system, as used by the
International Institute for Applied Systems Analysis
The International Institute for Applied Systems Analysis (IIASA) is an independent international research institute located in Laxenburg, near Vienna, in Austria. Through its research programs and initiatives, the institute conducts policy-or ...
(IIASA), are:
#
Polar desert
Polar deserts are the regions of Earth that fall under an ice cap climate (''EF'' under the Köppen classification). Despite rainfall totals low enough to normally classify as a desert, polar deserts are distinguished from true deserts (' or ' un ...
# Subpolar dry
tundra
In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless moun ...
# Subpolar moist tundra
# Subpolar wet tundra
# Subpolar rain tundra
#
Boreal
Boreal may refer to:
Climatology and geography
*Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch
*Boreal climate, a climate characterized by long winters and short, cool to mild ...
desert
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
# Boreal dry
scrub
# Boreal moist
forest
A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
# Boreal wet forest
# Boreal rain forest
#
Cool temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
desert
# Cool temperate
desert scrub
Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this ...
# Cool temperate
steppe
In physical geography, a steppe () is an ecoregion characterized by grassland plains without trees apart from those near rivers and lakes.
Steppe biomes may include:
* the montane grasslands and shrublands biome
* the temperate grasslands, ...
# Cool temperate moist forest
# Cool temperate wet forest
# Cool temperate rain forest
# Warm temperate desert
# Warm temperate desert scrub
# Warm temperate thorn scrub
# Warm temperate dry forest
# Warm temperate moist forest
# Warm temperate wet forest
# Warm temperate rain forest
#
Subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
desert
# Subtropical desert scrub
# Subtropical thorn woodland
#
Subtropical dry forest
The tropical and subtropical dry broadleaf forest is a habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive ...
#
Subtropical moist forest
Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forest, is a subtropical and tropical forest habitat (ecology), habitat type defined by the World Wide Fund for Nature.
Description
TSMF is generally foun ...
# Subtropical wet forest
# Subtropical rain forest
#
Tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
desert
# Tropical desert scrub
# Tropical thorn woodland
# Tropical very dry forest
#
Tropical dry forest
The tropical and subtropical dry broadleaf forest is a habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive ...
#
Tropical moist forest
Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forest, is a subtropical and tropical forest habitat type defined by the World Wide Fund for Nature.
Description
TSMF is generally found in large, discon ...
#
Tropical wet forest
Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forest, is a subtropical and tropical forest habitat type defined by the World Wide Fund for Nature.
Description
TSMF is generally found in large, discon ...
#
Tropical rain forest
Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equatori ...
See also
*
Andrew Delmar Hopkins
Andrew Delmar Hopkins (August 20, 1857 – September 22, 1948) was an American entomologist of the late 19th and early 20th centuries. Though self-taught, his scientific understanding of forest entomology was exceptional. He received an honor ...
*
Biome
A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
*
Ecoregion
An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
*
Holdridge life zones in Guatemala There are 14 Holdridge life zones
The Holdridge life zones system is a global bioclimatic scheme for the classification of land areas. It was first published by Leslie Holdridge in 1947, and updated in 1967. It is a relatively simple system base ...
*
Köppen climate classification
The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notabl ...
*
Life zone
The life zone concept was developed by C. Hart Merriam in 1889 as a means of describing areas with similar plant and animal communities. Merriam observed that the changes in these communities with an increase in latitude at a constant elevation ar ...
*
Trewartha climate classification
The Trewartha climate classification (TCC) or the Köppen–Trewartha climate classification (KTC) is a climate classification system first published by American geographer Glenn Thomas Trewartha in 1966. It is a modified version of the Köppen ...
References
[{{Cite web , title=holdridge life zone: Topics by Science.gov , url=https://www.science.gov/topicpages/h/holdridge+life+zone , access-date=2022-03-23 , website=www.science.gov , language=en]
Biogeographic realms
Sustainable building
Geographic classifications
Climate and weather classification systems