In this article we will discuss about the Phytogeographic Divisions and Maps of India.
Phytogeographic Divisions of India:
J.D. Hooker, the auther of Flora of British India marked 9 distinct areas according to the nature of vegetation. By “British India” he meant the vast tract that included the sub-continent of India, Burma, Malaya, Sri Lanka and the Maldiva and Laccadiva Islands.
These nine phytogeographic divisions are:
1. East Himalaya:
Sikkim, Bhutan and North Assam.
2. North West Himalaya:
From Kumaoon to Chitral (now in Pakistan).
3. Indus plain:
Undivided Punjab, Sind, Baluchistan, Kutch, North Gujrat, Rajasthan.
4. Gangetic Plain:
From the Aravalli Hills in the west to Sylhet and Assam in the East and Orissa as far south as Mahanadi. This is subdivided into Upper gangetic plain, Lower gangetic plain and the Sunderbans.
5. Malabar:
This stretches from the south of Gujarat to Kanyakumari and the Laccadiva Islands.
6. The Deccan:
The elevated land east of Malabar and south of the Indo-Gangetic plain, including the Coromandel Coast on the east.
7. Ceylon (Sri Lanka) and the Maldives Islands.
8. Burma.
9. Malaya.
In 1937 C.C. Calder published an account of the vegetation of India and distinguished 6 phytogeographic divisions (which he Called regions) as noted below:
1. The Eastern Himalaya:
Sikkim and the hilly tracts eastwards; divided into 3 subdivisions according to altitude as tropical, temperate and alpine zones.
2. The Western Himalaya:
From Kumaoon westwards to Chitral, i.e. similar to Western Himalaya of Hooker. Like the Eastern Himalaya here also he recognised 3 distinct zones according to altitudes.
3. The Indus Plain:
Similar to Hooker’s 3rd division, comprising Punjab (undivided), Sind, Rajputana west of the Aravalli Hills, Gujarat and Kutch.
4. The Gangetic plain:
Similar to that of Hooker and subdivided into Upper Gangetic plain, Lower Gangetic plain and the Sunderbans.
5. Malabar:
The hilly strip of land known as the Western Ghats.
6. Deccan:
The plateau of the Peninsular India east of Western Ghats and south of Gangetic plain. A subdivision is distinguished in the east as Coromandel, a strip of plain land east of the Eastern Ghat hill-range. D. Chatterjee while making a study of the endemic flora of India divided the subcontinent into 8 divisions excluding Burma.
Phytogeographic Maps:
Map. I:
1. The Deccan:
Mysore, Madras and major part of Hyderabad, i.e. the states of Karnataka, Tamil Nadu and Andhra Pradesh.
2. Malabar:
Comparable to Malabar division of Hooker and Calder consisting of the narrow strip of land south of Sind running to the southern-most part of the country and including the Western Ghat hills.
3. Indus plain:
Areas on either sides of the Indus, divisible into a drier tract of Sind, Baluchistan and Rajputana (or Rajasthan) and a comparatively humid tract of Punjab.
4. Gangetic plain:
Divisible into 3 smaller areas as (a) the comparatively drier tract of Punjab including Delhi upto Alahabad of Uttar Pradesh, (b) a comparatively humid tract including the rest of Uttar Pradesh, Bihar, Bengal (i.e. W. Bengal and Bangladesh) and (c) the Sunder-bans.
5. Assam:
The Brahmaputra valley and the Naga, Khasia and Jaintea hills.
6. East Himalaya:
Darjeeling, Sikkim, Bhutan and eastwards to Mishmi. This division is subdivided into 3 zones according to altitude, viz. (a) Tropical zone, from the plains upto 1800 mtr., (b) Temperate zone stretching from 1800-3500 mtr. and (c) Alpine zone above 3500 mtr.
7. Central Himalaya:
Nepal
8. West Himalaya:
Kumaoon to Kashmir and N.W. Frontier Province. Chatterjee’s classification deviates from that of Hooder and Calder that he divided the subcontinent into 8 divisions in place of 6. He distinguished a Central Himalayan division and an Assam division.
Hooker and Calder are both silent about Nepal Himalaya which is the Central Himalayan division of Chatterjee. Here we do not find a type of vegetation characteristic of a distinct phytogeographic division like other divisions but it is an area of transition of Western and Eastern Himalayan flora.
His Assam division however is very distinct. It is similar to the East Himalayan division in certain respects but there is no alpine zone. The temperate zone has many species of plants allied to those growing in East Himalaya while there are many species which are allied to the hills of Burma and Malaya.
Hooker and Calder included this hilly area in the gangetic plain division where it hardly fits in. Further Chatterjee arranges his phytogeographic divisions starting from S. India where according to him is found the relic vegetation of India.
Map. II:
Making an adjustment of the views of different authors and depending on the reports of the explorers visiting different parts of the country in recent times we may recognise 7 phytogeographic divisions of the subcontinent of India which are named below:
(i) West Himalaya
(ii) East Himalaya
(iii) Arid zone
(iv) Gangetic Plain
(v) Assam
(vi) Malabar
(vii) Deccan
The 2 Himalayan divisions are divided into 3 distinct zones according to altitude, viz.:
(a) Tropical zone,
(b) Temperate zone and
(c) Alpine zone.
The Tropical zone stretches up to 1800 m. from the foot of the hills. The Temperate zone occupies a belt from 1800 m. to 3500 m. and above this is the Alpine zone. In the Western Himalaya Temperate zone starts from 1000 m.
West Himalaya stretches from western part of Nepal westwards to Chitral and East Himalaya includes the rest of Nepal, Darjeeling district, Sikkim, Bhutan, northern part of Assam and Arunachal Pradesh. The arid zone is the division designated as the Indus Plain by the previous authors.
The gangetic plain is the area as described by D. Chatterjee and is divisible into:
(i) A drier tract including a portion of drier Punjab, Delhi and Uttar Pradesh up to Allahabad,
(ii) A comparatively humid tract including the rest of Uttar Pradesh, Bihar, West Bengal and Bangladesh, and
(iii) The littoral forests of the Sunderbans.
Assam division is also the same as that of Chatterjee including the Brahmaputra valley the Naga, Khasia and Jaintea hills. Malabar division is the same as that of Hooker, Calder and Chatterjee a narrow stretch of land south of Gujarat running to the southern-most point of the country and including the Western Ghat hills.
The seventh division Deccan includes a vast area east of the Western Ghats and south of the Gangetic plain.
This is the same as Hooker, Calder and Chatterjee, and as has been shown by Calder is divisible into 2 subdivisions, viz.:
(i) The plateau of the Peninsular India and
(ii) Coromandel, a strip of plain land east to Eastern Ghats.