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 based on few empirical data, giving objective criteria.[1] A basic assumption of the system is that both soil and the climax vegetation can be mapped once the climate is known.[2]
Holdridge life zone classification scheme. Although conceived as three-dimensional by its originator, it is usually shown as a two-dimensional array of hexagons in a triangular frame.
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 vegetation zones, but Mediterranean zones, and boreal 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.[3]
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,[4] 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 than Merriam's system.
Scientific relationship between the 3 axes and 3 indicatorsedit
Potential evapotranspiration (PET) is the amount of water that would be evaporated and transpired if there were enough water available. Higher temperatures result in higher PET.[5]Evapotranspiration (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 (AI), with an AI<0.2 indicating arid/hyperarid, and AI<0.5 indicating dry.[6]
Coldest /\ / \ PET - -- - Rain
The coldest regions have not much evapotranspiration nor precipitation as there is not enough heat to evaporate 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 systems to drain excess water into oceans.
On this map, a shift of 1 indicates that at the end of the century, the region had fully moved into a completely different Holdridge zone type from where it had been historically. The extent of the shifts will be dependent on the severity of the climate change scenario followed.[8]
Many areas of the globe are expected to see substantial changes in their Holdridge life zone type as the result of climate change, with more severe change resulting in more remarkable shifts in a geologically rapid time span, leaving less time for humans and biomes to adjust. If species fail to adapt to these changes, they would ultimately go extinct: the scale of future change also determines the extent of extinction risk from climate change. For humanity, this phenomenon has particularly important implications for agriculture, as shifts in life zones happening in a matter of decades inherently result in unstable weather conditions compared to what that area had experienced throughout human history. Developed regions may be able to adjust to that, but those with fewer resources are less likely to do so.[8]
Areas of the globe where agriculture would become more difficult perhaps to the point of leaving the conditions historically suitable for it, under low-emission and high-emission scenarios, by 2100.[8]
Some research suggests that under the scenario of continually increasing greenhouse gas emissions, known as SSP5-8.5, the areas responsible for over half of the current crop and livestock output would experience very rapid shift in its Holdridge Life Zones. This includes most of South Asia and the Middle East, as well as parts of sub-Saharan Africa and Central America: unlike the more developed areas facing the same shift, it is suggested they would struggle to adapt due to limited social resilience, and so crop and lifestock in those places would leave what the authors have defined as a "safe climatic space". On a global scale, that results in 31% of crop and 34% of livestock production being outside of the safe climmatic space. In contrast, under the low-emissions SSP1-2.6 (a scenario compatible with the less ambitious Paris Agreement goals, 5% and 8% of crop and livestock production would leave that safe climatic space.[8]
^US EPA, OA (January 29, 2013). . US EPA. Archived from the original on April 28, 2013.
^Harris SA (1973). "Comments on the Application of the Holdridge System for Classification of World Life Zones as Applied to Costa Rica". Arctic and Alpine Research. 5 (3): A187–A191. JSTOR 1550169.
^Leemans, Rik (1990). "Possible Changes in Natural Vegetation Patterns Due to a Global Warming". National Geophysical Data Center (NOAA). from the original on 2009-10-16.
^Lugo, A. E. (1999). "The Holdridge life zones of the conterminous United States in relation to ecosystem mapping". Journal of Biogeography. 26 (5): 1025–1038. doi:10.1046/j.1365-2699.1999.00329.x. S2CID 11733879. (PDF) from the original on 27 May 2015. Retrieved 27 May 2015.
^. agron-www.agron.iastate.edu. Archived from the original on 2020-01-28. Retrieved 2022-03-23.{{cite web}}: CS1 maint: archived copy as title (link)
^Parry, M. L.; Carter, T. R.; Konijn, N. T. (1988), The effects on Holdridge Life Zones, Dordrecht, The Netherlands: Springer, pp. 473–484, ISBN978-94-009-2965-4, retrieved 2022-03-23
^ abcdKummu, Matti; Heino, Matias; Taka, Maija; Varis, Olli; Viviroli, Daniel (21 May 2021). "Climate change risks pushing one-third of global food production outside the safe climatic space". One Earth. 4 (5): 720–729. doi:10.1016/j.oneear.2021.04.017. PMC8158176. PMID 34056573.
February 16, 2024
holdridge, life, zones, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, dec. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Holdridge life zones news newspapers books scholar JSTOR December 2021 Learn how and when to remove this template message 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 based on few empirical data giving objective criteria 1 A basic assumption of the system is that both soil and the climax vegetation can be mapped once the climate is known 2 Holdridge life zone classification scheme Although conceived as three dimensional by its originator it is usually shown as a two dimensional array of hexagons in a triangular frame Contents 1 Scheme 2 Scientific relationship between the 3 axes and 3 indicators 3 Classes 4 Climate change 5 See also 6 ReferencesScheme editWhile it was first designed for tropical and subtropical areas the system now applies globally The system has been shown to fit not just tropical vegetation zones but Mediterranean zones and boreal 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 3 The three major axes of the barycentric subdivisions are precipitation annual logarithmic biotemperature mean annual logarithmic potential evapotranspiration ratio PET to mean total annual precipitation Further indicators incorporated into the system are humidity provinces latitudinal regions altitudinal beltsBiotemperature 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 4 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 than Merriam s system Scientific relationship between the 3 axes and 3 indicators editPotential evapotranspiration PET is the amount of water that would be evaporated and transpired if there were enough water available Higher temperatures result in higher PET 5 Evapotranspiration 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 AI with an AI lt 0 2 indicating arid hyperarid and AI lt 0 5 indicating dry 6 Coldest PET Rain The coldest regions have not much evapotranspiration nor precipitation as there is not enough heat to evaporate 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 systems to drain excess water into oceans Classes editAll the classes defined within the system as used by the International Institute for Applied Systems Analysis IIASA are 7 Polar desert Subpolar dry tundra Subpolar moist tundra Subpolar wet tundra Subpolar rain tundra Boreal desert Boreal dry scrub Boreal moist forest Boreal wet forest Boreal rain forest Cool temperate desert Cool temperate desert scrub Cool temperate steppe 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 desert Subtropical desert scrub Subtropical thorn woodland Subtropical dry forest Subtropical moist forest Subtropical wet forest Subtropical rain forest Tropical desert Tropical desert scrub Tropical thorn woodland Tropical very dry forest Tropical dry forest Tropical moist forest Tropical wet forest Tropical rain forestClimate change editSee also Effects of climate change on biomes and Effects of climate change on agriculture nbsp On this map a shift of 1 indicates that at the end of the century the region had fully moved into a completely different Holdridge zone type from where it had been historically The extent of the shifts will be dependent on the severity of the climate change scenario followed 8 Many areas of the globe are expected to see substantial changes in their Holdridge life zone type as the result of climate change with more severe change resulting in more remarkable shifts in a geologically rapid time span leaving less time for humans and biomes to adjust If species fail to adapt to these changes they would ultimately go extinct the scale of future change also determines the extent of extinction risk from climate change For humanity this phenomenon has particularly important implications for agriculture as shifts in life zones happening in a matter of decades inherently result in unstable weather conditions compared to what that area had experienced throughout human history Developed regions may be able to adjust to that but those with fewer resources are less likely to do so 8 nbsp Areas of the globe where agriculture would become more difficult perhaps to the point of leaving the conditions historically suitable for it under low emission and high emission scenarios by 2100 8 Some research suggests that under the scenario of continually increasing greenhouse gas emissions known as SSP5 8 5 the areas responsible for over half of the current crop and livestock output would experience very rapid shift in its Holdridge Life Zones This includes most of South Asia and the Middle East as well as parts of sub Saharan Africa and Central America unlike the more developed areas facing the same shift it is suggested they would struggle to adapt due to limited social resilience and so crop and lifestock in those places would leave what the authors have defined as a safe climatic space On a global scale that results in 31 of crop and 34 of livestock production being outside of the safe climmatic space In contrast under the low emissions SSP1 2 6 a scenario compatible with the less ambitious Paris Agreement goals 5 and 8 of crop and livestock production would leave that safe climatic space 8 See also editAndrew Delmar Hopkins Biome Ecoregion Koppen climate classification Life zone Trewartha climate classificationReferences edit US EPA OA January 29 2013 About the National Health and Environmental Effects Research Laboratory NHEERL US EPA Archived from the original on April 28 2013 Harris SA 1973 Comments on the Application of the Holdridge System for Classification of World Life Zones as Applied to Costa Rica Arctic and Alpine Research 5 3 A187 A191 JSTOR 1550169 Leemans Rik 1990 Possible Changes in Natural Vegetation Patterns Due to a Global Warming National Geophysical Data Center NOAA Archived from the original on 2009 10 16 Lugo A E 1999 The Holdridge life zones of the conterminous United States in relation to ecosystem mapping Journal of Biogeography 26 5 1025 1038 doi 10 1046 j 1365 2699 1999 00329 x S2CID 11733879 Archived PDF from the original on 27 May 2015 Retrieved 27 May 2015 potential evapotranspiration esdac jrc ec europa eu Retrieved 2022 03 23 Archived copy agron www agron iastate edu Archived from the original on 2020 01 28 Retrieved 2022 03 23 a href Template Cite web html title Template Cite web cite web a CS1 maint archived copy as title link Parry M L Carter T R Konijn N T 1988 The effects on Holdridge Life Zones Dordrecht The Netherlands Springer pp 473 484 ISBN 978 94 009 2965 4 retrieved 2022 03 23 a b c d Kummu Matti Heino Matias Taka Maija Varis Olli Viviroli Daniel 21 May 2021 Climate change risks pushing one third of global food production outside the safe climatic space One Earth 4 5 720 729 doi 10 1016 j oneear 2021 04 017 PMC 8158176 PMID 34056573 Retrieved from https en wikipedia org w index php title Holdridge life zones amp oldid 1196584726, wikipedia, wiki, book, books, library,
