Holdridge Life Zone Model



Mean annual
biotemperature (
oC)


Potential evaporation ratio


Humidity Province

Average total annual precipitation (cm)

Polar

<1.5

0.125-1.5

6.25-75

           

Subpolar (Alpine)

Tundra

 

Dry

1.5-3

1-2

Subhumid

6.25-12.5

 

Moist

1.5-3

0.5-1

Humid

12.5-25

 

Wet

1.5-3

0.25-0.50

Perhumid

25-50

 

Rain

1.5-3

0.125-0.25

Superhumid

50-100

           

Boreal (Subalpine)

Desert

3-6

2-4

Semiarid

6.25-12.5

Boreal

Dry Scrub

3-6

1-2

Subhumid

12.5-25

Boreal

Forest

       
 

Moist puna

3-6

0.50-1

Humid

25-50

 

Wet paramo

3-6

0.25-0.50

Perhumid

50-100

 

Rain paramo

3-6

0.125-0.25

Superhumid

100-200

           

Cool Temperate

Desert

6-12

4-8

Arid

6.25-12.5

Cool Temperate

Desert Scrub

6-12

2-4

Semiarid

12.5-50

Cool Temperate

Tundra Dry

6-12

1-2

Subhumid

25-50

Cool Temperate

Forest

       
 

Moist

6-12

0.5-1

Humid

50-100

 

Wet

6-12

0.25-0.5

Perhumid

100-200

 

Rain

6-12

0.125-0.25

Superhumid

200-400

           

Subtropical

Desert

12-24

8-16

Periarid

6.25-12

Subtropical

Desert Scrub

12-24

4-8

Arid

12-25

Subtropical

Thorn Woodland

12-24

2-4

Semiarid

25-50

Subtropical

Forest

       
 

Dry

12-24

1-2

Subhumid

50-100

 

Moist

12-24

0.5-1

Humid

100-200

 

Wet

12-24

0.25-0.5

Perhumid

200-400

 

Rain

12-24

0.125-0.25

Superhumid

400-800

           

Tropical

Desert

>24

16-32

Superarid

6.25-12

Desert Scrub

>24

8-16

Periarid

12-25

Tropical

Thorn Woodland

>24

4-8

Arid

25-50

Tropical

Forest

       

Very Dry

>24

2-4

Semiarid

50-100

Dry

>24

1-2

Subhumid

100-200

Moist

>24

0.5-1

Humid

200-400

Wet

>24

0.25-0.5

Perhumid

400-800

Rain

>24

0.125-0.25

Superhumid

>800

 

Email your Comments, Questions or Suggestions to geirs@cieer.org
Copyright 1998-2001. CIEER Inc. All rights reserved.