Hansen (1920) divides 8 zones on either side of equator. The three latitude zohes are (1) Polar (2) Temperate (3) Tropical.
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1. Equator:
0 -15.0 degree on either side of equator.
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2. Tropical zone:
15 – 23.5 degree on either side of equator.
3. Subtropical zone:
23.5 – 34.0 degree on either side of equator.
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4. Warm temperate zone:
34.0 – 45.0 degree on either side of equator.
5. Cold temperate zone:
45.0 – 58.0 degree on either side of equator.
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6. Subarctic zone:
58.0 – 66.5 degree on either side of equator.
7. Arctic zone:
66.5 – 72.0 degree on either side of equator.
8. Polar zone:
72.0 – 90 degree on either side of equator.
Distribution of Plant along altitudes:
0 – 600 m: Zone of plums & bananas.
600 – 1250 m: Tree ferns and figs.
1250 – 1900 m: Pines, miscellaneous.
1900 – 2600 m: Evergreen trees
2600 – 3200 m: Deciduous trees.
3200 – 3800 m: Coniferous trees.
3800 – 4450 m: Alpine shrubs.
4450 – 5050 m: Alpine herbs.
5050 – Above: Ice and snows.
Chief Vegetation Belt of the Earth
On the basis of climate and geographical conditions the earth is usually divided into four broad vegetation belts:
A. Arctic Zone: Two types:
1. Arctic proper: North Pole.
2. Sub arctic: Southern arctic to North Temperate Zone.
B. North Temperate Zone:
between 30°N latitude and 55°N latitude, two major zones:
(1) North temperate of the eastern zone:
04 zones:
(a) Western and Central Europe.
(b) Mediterranean
(c) Northern Africa.
(d) Himalayas, eastern Asia and Japan.
(2) North temperate to the Western hemisphere.
C. Tropical Zone:
Two sub zones –
(a) Palaeotropic –
(a) Tropical Africa, (b) Tropical Asia.
(b) Neotrophic
D. South Temperate Zone:
Africa, Australia, New Zealand.