flowering plant diversity and endemism in india: an ...

ISSN 0975 - 9573

ANU J. Nat. Sci. 1(1), 27-39 (2010) 27

FLOWERING PLANT DIVERSITY AND ENDEMISM IN INDIA: AN OVERVIEW Vatsavaya S. Raju*, C. S. Reddy1 and Sateesh Suthari

Plant Systematics Laboratory, Department of Botany, Kakatiya University Warangal, Andhra Pradesh - 506 009, India 1 Forestry & Ecology Division, National Remote Sensing Centre Balanagar, Hyderabad, Andhra Pradesh - 500 037, India

Abstract: An overview of the flowering plant diversity and endemism in India is attempted. India is one of the megadiversity nations in the world. It has about 19,530 species of flowering plants of which 5400 are endemic. It forms one (Hindustan Region) of the Vavilovian Centers for agrobiodiversity having contributed 167 species to the world of agriculture. India is the home for 320 species of wild relatives of crops and has 16 major forest types diversified into 221 minor forest types. A birds eye view of flora of India, biogeographic zones, vegetation types, forest types, floristic richness, species abundance of the top ten angiosperm families and families of aquatic and insectivorous plants, list of extinct Angiosperms, endemism in regard to States and Union Territories, and the names of 25 hot spots are provided. Key words: India, Angiosperm diversity, endemism, hot spots.

Introduction Flowering Plants or Angiosperms (Angiospermae/Anthophyta/Magnoliophyta) are the most numerous, highly diverse and successful extant group of higher plants in the tropics. They constitute a monophyletic taxon and a kin to Gymnosperms with which they constitute the seed plants or Spermatophyta. The Angiosperms are distinguished from the other land plants, with several of their apomorphies, namely: sieve tube members with companion cells, flowers bearing perianth, carpels and fruits, ovules with integuments, stamens with two lateral thecae, male gametophyte trinucleate, female gametophyte 8-nucleate, triple fusion and double fertilization (APG II, 2003). Flowering plants are the dominant taxon on the earth today, constituting 300 to 400 families with 2,50,000 to 3,00,000 species in comparison to 16,000 species of Bryophytes, 13,000 species of Pteridophytes and 750 species of Gymnosperms (Table 1). In evolutionary terms, flowering plants are relatively recent, with fossil evidence indicating their first emergence at around 140 m years ago in

the early Cretaceous, followed by rapid diversification and radiation in the mid-Cretaceous (Willis and McElwain, 2002). Indian Peninsula India has a characteristic geographic location (6 45' to 370 6N latitude and 680 7' to 970 25' E longitude) with terrestrial land of about 15,200 km and a coastline of 7,516 km. Its geographical area is 3287.263 sq km (3,287 m ha). It is the seventh largest country in the world and the second largest in Asia. 0

Physiographically, the Indian mainland may be divided into three distinct regions: the Himalaya, the Indo-Gangetic Plain, and the Peninsular India. The Himalaya forms a mountain chain along the extreme northern margins of India, extending east-west for about 2,500 km, varying in width between 240 to 340 km, occupying an area about 5, 00, 000 sq km in India, and rising from the low lying Indian plains to the highest peaks at Kanchenjunga (8,586 m) in Sikkim. The Indo-Gangetic Plain comprises alluvial low lands lying parallel to the south of the Himalaya (ca. 2,400 km). This region is agriculturally more

* Corresponding author : [email protected] ANU Journal of Natural Sciences w June 2010 w

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Vatsavaya et al.

Table 1. The ratio of the number of Protista and Plantae occurring in India against the global numbers. Kingdoms

India

World

% Species in India/World

PROTISTA Algae

2,500

40,000

6.25

Fungi

23,000

47,000

48.94

2,450

17,000

11.41

Bryophytes

2,843

16,000

17.77

Pteridophytes

1,022

13,000

7.86

64

750

8.53

2,50,000

7.00

Lichens PLANTAE

Gymnosperms Angiosperms

19,530*

*Includes 282 subspecies and 2,206 varieties.

productive. The Peninsular India lies south of the Indo-Gangetic Plain; the two being separated roughly by the boundary of Tropic of Cancer. Biodiversity Biodiversity is the variation of life forms within a given ecosystem, biome, or on the entire Earth (biosphere). Biodiversity is organized at three levels, viz. genetic, species and ecosystem. The present paper deals with the plant diversity of the Indian nation at species and ecosystem levels. For convenience and practical reasons, biodiversity is discussed under natural (wild diversity), and manipulated or human impacted or domesticated diversity (agrobiodiversity). (A) Wild Diversity (i) Genetic Diversity: It is concerned with the variation in genes within a particular species. Billions of individuals are produced through sexual reproduction. Each differs from the other in its hereditary constitution or the genetic information contained in its genes. It is this difference which has given us beautiful butterflies, roses, parakeets or corals in a myriad hues, shapes and sizes. Examples: Brown Bear, Sloth Bear, Himalayan black Bear; Himalayan Tahr, Nilgiri Tahr. ANU Journal of Natural Sciences w June 2010 w

(ii) Species Diversity: It refers to the variety of living organisms on earth. Species differ from one another markedly in their genetic makeup and do not interbreed in nature. Species are defined variously as morphological, biological, genetic, cladistic, ecological and evolutionary. Closely related species, however, have much of their hereditary material in common. For instance, humans and chimpanzees have about 98.4% of the same genes. The Botanical and Zoological Surveys of India have estimated the number of biological organisms occurring in the country to be 1,26,188 species. These represent the five kingdoms, namely Monera, Protista, Fungi, Plantae and Animalia. According to the World Conservation Monitoring Centre (WCMC, 1992), 1,604,000 species have been described at the global level. Thus, India accounts for 8% of the global biodiversity residing in only 2.4% land area of the world. Of this, the flowering plants constitute 249 families, 2984 genera, 17,053 species, 282 subspecies, 2206 varieties, 33 sub-varieties and 68 forma (Table 2). According to Nayar (1989), the number of flowering plant species endemic to the present political boundaries of this country is 4900 out of a total of 15000, i.e. 33 %. Hajra and Mudgal (1997) reported 5400 endemics of 17000 angiospermous species found India (i.e. 31.76%).

Flowering Plant Diversity and Endemism ...

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Table 2. Statistical analysis of flowering plants of India. Families

Genera

Species

Subspecies

203

2,282

12,575

237

1,771

30

50

46

702

4,448

45

432

03

18

249

2,984

17,053

282

2,206

33

68

Dicots Monocots Total

Varieties Sub-varieties

Forma

Data based on Karthikeyan (1999) and updated.

The top ten dominant angiosperm families of India are enlisted in Table 3. Poaceae in Monocots and Asteraceae in Dicots predominate with 1225 (225 genera) and 1000 (161 genera) taxa, respectively. There are 17 taxa (11 monocots and 16 dicots) of Angiosperms which are construed to be extinct in the wild. These include the palm Corypha taliera Roxb., three species of Ophiorrhiza, two species of Dipcadi, the orchids Calanthe whiteana and Pleione lagenaria (Table 4). Table 3. The first ten large families of Angiosperms in India. Family

No. of Genera

No. of Species

1 Poaceae

225

1,225

2 Asteraceae

161

1,000

3 Orchidaceae

145

990

4 Fabaceae

123

775

5 Rubiaceae

90

495

6 Cyperaceae

24

449

7 Euphorbiaceae

74

419

8 Lamiaceae

68

393

9 Acanthaceae

84

379

66

356

10 Scrophulariaceae

himalayana Griff. and Mitrastemon yamamotoi Makino of Rafflesiaceae, with only the flower (representing the whole plant) projecting from the roots of the host plant, form an unusual case of botanical interest. Similarly, Balanophora dioica R.Br., Boschiniaekia himalaica Hook.f. & Thoms., Aeginitia indica Roxb. are the other root parasites of great morphological interest. Genera like Galeola, Epipogium and Monotropa are the best examples of saprophytes. Among the insectivorous plants Nepenthes khasiana Hook.f., Drosera burmannii Vahl, D. peltata Sm., Utricularia spp. and Aldrovanda spp. are of significant interest. The families with characteristic insectivorous plants are Lentibulariaceae (36 spp.), Droseraceae (3 spp.) and Nepenthaceae (1 sp.). Poa litorosa (Poaceae), the Angiosperm with highest chromosome number, also occurs in India. The parasitic families represented are Orobanchaceae (54 spp.), Loranthaceae (46 spp.), Rafflesiaceae (1 sp.), Santalaceae (10 spp.), Balanophoraceae (6 spp.), and Cuscutaceae (12 spp.). The taxa of Podostemaceae and Tristichaceae grow on rocks in flowing streams. Metal-tolerant species are found in the families Brassicaceae, Caryophyllacee, Cerotophyllaceae, Fabaceae, Portulacaceae, Salvadoraceae, Tamaricaceae and Thymelaeaceae while the families Chenopodiaceae, Basellaceae, Amaranthaceae and Phytolaccaceae are salt-tolerant. (iii) Ecosystem Diversity:

Several plants, say the species of Arenaria, Thylacospermum, Acantholimon and Festuca that occur especially in the high alpine meadows survive the extreme adverse ecological conditions by special adaptations. The woolly species of Saussurea form an interesting plant of the Western Himalaya. Sapria

This refers to the variety of habitats or ecosystems. A habitat is the sum total of the climate, vegetation and geography of a region. There are several kinds of habitats around the globe. These are organized into biomes like tundra, taiga, forests, grasslands, savannahs and deserts on the terrestrial ANU Journal of Natural Sciences w June 2010 w

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Vatsavaya et al.

Table 4. Extinct Angiosperm species from the wild in India and the regions with in. Species

Family

State/Region

1

Calanthe whiteana King & Pantl.

Orchidaceae

Sikkim

2

Carex repanda C.B. Clarke

Cyperaceae

Assam, Meghalaya

3

Corypha taliera Roxb.

Arecaceae

India

4

Dicliptera abuensis Blatter

Acanthaceae

Rajasthan

5

Dipcadi concanense (Dalzell) Baker

Liliaceae

Western Ghats

6

Dipcadi reidii Deb & S. Dasgupta

Liliaceae

Western Himalaya

7

Drimia polyphylla (Hook.f.) Ansari & Sundararagha.

Asparagaceae

Deccan Peninsula

8

Eragrostis rottleri Stapf

Poaceae

Tamil Nadu

9

Eriochrysis rangacharii C.E.C. Fischer

Poaceae

Tamil Nadu

10

Hedychium marginatum C.B. Clarke

Zingiberaceae

Nagaland

11

Hubbardia heptaneuron Bor

Poaceae

Karnataka

12

Ophiorrhiza brunois Wight & Arn.

Rubiaceae

Western Ghats

13

Ophiorrhiza caudata C.E.C. Fischer

Rubiaceae

Kerala

14

Ophiorrhiza radicans Gardn.

Rubiaceae

Kerala

15

Pleione lagenaria (Lindl.) Landl. & Paxton

Orchidaceae

Meghalaya

16

Sterculia khasiana Debberman

Sterculiaceae

Meghalaya

17

Wenlandia angustifolia Wight ex Hook.f.

Rubiaceae

Andhra Pradesh, Tamil Nadu

land. The aquatic ecosystems are the counter parts though directly they cannot be easily recognized like the biomes on the land. Three types of ecosystem diversity are realized at the level of communities: (a)

Alpha (a) diversity: It is the species diversity within the same community or habitat, with two components called species richness and evenness of species. At times, one species dominates the cover in a forest habitat.

(b)

Beta (b) diversity: It is the diversity between the communities or habitats. It is the species turn over per unit change in habitat. Greater is the dissimilarity between the communities, higher is the beta diversity since the species alter with the abiotic and biotic changes in the habitat, and

ANU Journal of Natural Sciences w June 2010 w

(c)

Gamma (g) diversity: It is the overall diversity of the habitats on a landscape or geographic area. It includes both alpha and beta diversities. The ecological diversity is described further under Biogeography.

Aquatic Plant Diversity The Indian region has approximately worlds half of the aquatic flowering plants. The aquatic families in the Indian flora are Alismataceae (5 genera, 8 spp.), Aponogetonaceae (6 spp.), Barclayaceae (2 spp.), Butomaceae (1 sp.), Cabombaceae (2 genera, 2 spp.), Callitrichaceae (2 spp.), Ceratophyllaceae (3 spp.), Hydrocharitaceae (8 genera, 13 spp.), Lemnaceae (4 genera, 14 spp.), Najadaceae (7 spp.), Nelumbonaceae (1 sp.), Nymphaeaceae (2 genera, 7 spp.), Podostemaceae (11 genera, 24 spp.), Pontederiaceae (2 genera, 3


spp.), Potamogetonaceae (6 spp.), Ruppiaceae (1 sp.), Trapaceae (2 spp.), Typhaceae (4 spp.) and Zanichelliaceae (1 sp.). (B) Agrobiodiversity It is the agricultural biodiversity, the backbone for global economy and food security. Over centuries, farmers developed crop varieties and maintained their diversity to meet the needs of their families and the farming systems. Still millions of farmers and local communities use this resource pool as the basis for the livelihood. This diversity is immense and invaluable. For example, a single species of rice collected from the wild in the distant past has diversified into 50,000 varieties as a result of the ingenuity and innovative skills of the farming communities all over the eastern countries. India is an important center of agrobiodiversity having contributed 167 species to the world agriculture and being homeland for 326 species of wild relatives of crops. It is the Hindustan Region, a centre of origin of cultivated crops (Vavilov, 1926). The numbers of species of crop wild relatives contributed by India to global agrobiodiversity are 55 vegetables and pulses, 51 millets, 104 fruit plants, 27 spices and condiments, 24 fibre crops, 12 oil seeds, tea, coffee, tobacco and sugarcane besides the 3000 medicinal plants (MoEF, 1999). Turmeric (Curcuma longa L.; C. domestica Val.) which is widely cultivated in India has 50 local cultivars, often associated with places of origin (selection), to mention for example Allepey, Bilaspur and Himachal turmeric. Biogeography Biogeography is the science which deals with patterns of distribution of living organisms and the processes that results in such patterns. India is at the junction of the three major biogeographic realms, namely, the Indo-Malayan, the Eurasian and the Afrotropical. It is considered to be one of the twelve centres of origin and diversity of several plant species in the world. Sir J.D. Hooker (1904) remarked that The Indian flora is more varied than that of any other country of equal area in the Eastern Hemisphere, if not on the globe. Change in climatic conditions is accompanied by a change in vegetation as well. For

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instance, cactus and thorny scrub replace grassland or forests as the climate changes from temperate to hot and dry conditions. Each species is adapted to a particular kind of environment. As the environment changes, species best adapted to that environment become predominant. Thus, the variety or diversity of species in the ecosystem is influenced by the ecosystem itself. The environmental changes within an ecosystem lead to genetic diversity or diversity within the same species. Several phytogeographers (Hooker, 1854, 1904; Chatterjee, 1939; Razi, 1955; Puri, 1960; Udvardy, 1975; Rodgers and Panwar, 1988) have variously divided the Indian region under a number of phytogeographical provinces, based on the floristic composition, the naturalness of the flora, and the local climate. A slightly modified version of the biogeographic classification proposed by Rodgers and Panwar (1988) is followed (Table 5). Indias rich vegetation wealth is undoubtedly due to the immense variety of the climatic and altitudinal variations coupled with varied ecological habitats. There are almost rainless areas to the highest rainfall area in the world. The altitude varies from the sea level to the highest mountain ranges of the world. The habitat types vary from the humid tropical Western Ghats to the hot desert of Rajasthan; from cold desert of Ladakh and icy mountains of the Himalayas to the long, warm coast line stretches of Peninsular India. The political boundaries and the vegetation types encountered in the 12 biogeographic zones of India are provided in Table 5. The extreme diversity of the habitats has resulted in such luxuriance and variety of flora and fauna. Almost all types of forests, ranging from scrub forest to the tropical evergreen rain forest, coastal mangrove to the temperate and alpine flora occur in India. Champion and Seth (1968) have recognized 16 major forest types with 221 minor types. Of the 16 types, we have 14 types represented currently. The area under these forest types and the percentage area (cover) are presented in Table 6. The Littoral Swamp forests, Tropical Dry Evergreen, Sub-tropical Dry Evergreen and Broad-leaved hill forests and Himalayan Dry Temperate forests are in less than 1% area while Tropical Moist Deciduous (33.92%) and Tropical Dry Deciduous (30.16%) forests ANU Journal of Natural Sciences w June 2010 w

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Vatsavaya et al.

Table 5. Biogeographic zones of India: Political boundaries and vegetation types. Biogeographic Zone

Political Boundary

Vegetation Types

1 Trans-Himalaya

Ladakh (Jammu & Kashmir), Lahul and Spiti (Himachal Pradesh).

Alpine scrubs, trees conspicuously absent, except the planted ones.

2 West Himalaya

Jammu & Kashmir (except Ladakh), Himachal Pradesh (except Lahul & Spiti), Garhwal and Kumaon (Uttar Pradesh).

Tropical, Subtropical, Temperate, Subalpine, Alpine.

3 East Himalaya

Sikkim, Darjeeling (West Bengal), Arunachal Pradesh.

Tropical, Subtropical, Temperate, Subalpine.

4 North-East India

Assam, Manipur, Meghalaya, Mizoram, Nagaland, Tripura.

Tropical, Subtropical, Temperate, Subalpine.

5 The Indian Desert

Western and North Western region of Rajasthan; part of Kutch region of Gujarat.

Vegetation of sand dunes, sandy and hammcky plains, gravelly and rocky plains, saline tracts.

6 Semi-Arid zone

Punjab plains, Haryana, Delhi; fringes of Jammu, Himachal Pradesh; western edge of Uttar Pradesh, eastern Rajasthan and Gujarat; North-west Madhya Pradesh.

Deciduous forests; open scrubs.

7 Gangetic Plains

From eastern Rajasthan through Uttar Pradesh to Bihar and West Bengal.

Secondary vegetation of xerophytes and open dry grasslands.

8 Deccan Peninsula

Most of Maharashtra, Madhya Pradesh, Karnataka, Tamil Nadu, Andhra Pradesh and Orisssa.

Dry scrubs; dry deciduous, moist deciduous, semi-evergreen.

9 Western Ghats

Narrow stretch from south of river Tapati to Kanyakumari along the west coast.

Dry scrubs; dry deciduous, moist deciduous, semi-evergreen, evergreen, sholas and grasslands.

10 Indian Coasts

Coast line of India from Gujarat to Kanyakumari in the west; Sunderbans to Kanyakumari in the east.

Submerged vegetation, Mangrove and beach forests.

11 Andaman and Nicobar Islands

Group of 348 Islands, islets in the Bay of Bengal.

Submerged and Strand vegetation; Mangrove, tidal, evergreen, semi-evergreen and moist deciduous forests; grasslands.

12 Lakshadweep Islands

Archipelago of 27 small Islands in the Arabian sea.

Virtually no natural vegetation left; coconut plantations common.

predominate while constituting 64.08% of the area (4,23,414 sq km). India as the Megadiverse Nation Biodiversity is unevenly distributed among the worlds nations which exist as Political States. Species richness or diversity is high in the tropics and the cold depths of the oceans, as both these regions are somewhat protected from disturbances due to inaccessibility. Rapid change in environment as at the seashore and long tracts of mountains also ANU Journal of Natural Sciences w June 2010 w

account for high species turnover. Barely a dozen countries lying partly or entirely in the tropics account for 60 to 70% of the worlds biodiversity. They are referred to as Megadiverse Nations or Countries. These are a group of countries that harbour the majority of the Earths species and therefore considered extremely biodiverse. Conversely, these are the Earths wealthiest nations. The United Nations Environment Programme has an agency called World Conservation Monitoring Centre (WCMC), which identified 17 megadiverse nations which are mostly located in the tropics.


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Table 6. Current forest cover in India against Forest types of Champion and Seth (1968). Forest Type

Area in sq km

Percentage*

1

Tropical Wet Evergreen forest

51,249

8.75

2

Tropical Semi-Evergreen forest

26,424

3.35

3

Tropical Moist Deciduous forest

236,794

33.92

4

Tropical Dry Deciduous forest

186, 620

30.16

5

Littoral and Swamp forest

4,046

0.38

6

Tropical Thorn forest

16,491

5.11

7

Tropical Dry Evergreen forest

1,404

0.29

8

Subtropical Broad-leaved Hill forest

2,781

0.38

9

Subtropical Pine forest

42,377

5.99

10

Subtropical Dry Evergreen forest

12,538

0.36

11

Montane Wet Temperate forest

23,365

3.45

12

Himalayan Moist Temperate forest

22,012

3.79

13

Himalayan Dry Temperate forest

312

0.28

14 -16

Sub-Alpine, Moist Alpine and Dry Alpine forest

18,628

3.79

Total

100.00

* Exclusively based on FSI 2007 data (FSI, 2009 Report).

Megadiversity is a concept first proposed in a paper at the Smithsonians 1988 Biodiversity Conference. This approach looks at biodiversity priorities by political units, in this case sovereign nations, rather than by ecosystems. It recognizes that a very small number of units (17 countries out of a global 200+) are home to an inordinately large share of the worlds biodiversity (USA, Mexico, Colombia, Venezuela, Ecuador, Peru, Brazil, Democratic Republic of Congo, South Africa, India, Madagascar, Malaysia, Indonesia, China, Philippines, Papua New Guinea and Australia). Most of the megadiversity areas are large, but several, such as Madagascar, the Philippines, and Ecuador pack high diversity into relatively small land areas (Mittermeier et al., 1999). India ranks 11th position in the world in presence of high diversity of flora and fauna. The species richness of different animal (mammals, birds, reptiles, amphibians) and plant species (angiosperms) for each country of the top 10 megadiverse nations is

provided in Table 7. The number of endemic taxa is provided in parentheses. As many as 131 plant species are stated to be primitive. The presence of a large number of primitive flowering plants in India renders the region a cradle of flowering plants (Takhtajan, 1969). Endemism The word endemic is ascribed to any taxon which has a restricted distribution. Endemics are commonly categorized in four contexts of spatial distribution: site or restricted area, biotope, biogeographical region and political area. Because of their narrow distributional zonation, endemics receive high priority for conservation. Endemism is a special criterion in conservation of any area. The flora of India shows close affinity with the flora of Indo-Malaya and Indo-Chinese regions. According to Nayar (1977), 35% of Indian flora has ANU Journal of Natural Sciences w June 2010 w

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Vatsavaya et al.

Table 7. Megadiversity nations of the World. Country

Number of Mammals

Number of Birds

Number of Reptiles

Number of Amphibians

Number of Angiosperms

1

Australia

255 (210)

650 (355)

686 (616)

197 (169)

23,000 (14,458)

2

Brazil

428 (131)

622 (>191)

467 (172)

516 (294)

55,000 (17,500)

3

China

394 (77)

1195 (99)

270 (133)

265 (175)

27,000 (10,000)

4

Columbia

359 (28)

1721 (>142)

383 (97)

407 (367)

45,000 (16,000)

5

Ecuador

280 (21)

1447 (37)

345 (114)

358 (138)

15,000 (4,500)

6

India

372 (44)

1224 (52)

408 (187)

246 (110)

17,000 (5,400)

7

Indonesia

515 (201)

1519 (397)

600 (150)

270 (100)

20,000 (16,000)

8

Madagascar

105 (77)*

250 (103)

269 (74)

144 (76)

10,000 (9,200)

9

Malaysia

293 (27)

1200 (11)

294 (68)

171 (57)

15,000 (7,250)

10

Mexico

449

1010

717

282

25,000

11

Peru

361 (46)

1703 (109)

297 (98)

251 (>89)

20,000 (5,356)

12

Zaire

409

1086

280

216

10,000

The numbers in parentheses indicate the endemic taxa for each nation. * Source Groombridge and Jenkis (1994).

south-east Asian and Malayan, 8% temperate, 1% steppe, 2% African and 5% Mediterranean-Iranian elements. The adventive weeds and naturalised aliens constitute only 18%. This fact prompted Hooker (1904) to arrive at the erroneous conclusion that India has no flora of its own (as a separate entity) but is an admixture of the floras from adjacent countries. For the first time, Chatterjee (1939) reported 6,850 plant species as endemic to India. The subsequent phytogeographers, after critical analysis of flora, have convincingly concluded that India has a flora of its own. Of the 5400 taxa, 33% are endemic (confined to present Indian boundaries). In fact, India is said to harbour more endemic plant species than any other region of the world except Australia. There are about 140 endemic genera distributed over 47 families. The total endemic genera in India represent 6.5% of the 2984 genera occurring in India. The largest endemic genera are Pteracanthus and Nilgirianthus of Acanthaceae, with 20 species each. There are 8000 species of flowering plants in the Himalaya. Of these, 3,165 are endemic. The areas rich in endemism are the northeast India, ANU Journal of Natural Sciences w June 2010 w

followed by southern parts of peninsular India, and northwestern Himalaya. The northwest Himalaya is estimated to harbour about 1000 endemics, of the 3000 total species, while the Eastern Himalaya has about 1500 endemic species of 4500 species. Peninsular India has 6000 species of which 2000 are endemic. The Andaman and Nicobar Islands contribute 353 species to the endemic flora of India. The Poaceae are one of the largest families, having about 360 endemic taxa. Hotspots A seminal paper by Norman Myers in 1988 first identified ten tropical forest hotspots characterized both by exceptional levels of plant endemism and by serious levels of habitat loss. In 1990, Myers added a further eight hotspots, including four Mediterranean-type ecosystems. Conservation International adopted Myers hotspots as its institutional blueprint in 1989, and in 1996. To qualify as a hotspot, a region must meet two strict criteria: it must contain at least 1,500 species of vascular plants (> 0.5% of the worlds total) as endemics, and it has to have lost at least 70% of its original habitat.


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In the 1999 analysis (Mittermeier et al., 1999), published in the book Hotspots: Earths Biologically Richest and Most Endangered Terrestrial Ecoregions, and a year later in the scientific journal Nature (Myers et al., 2000), 25 biodiversity hotspots were identified. Collectively, these areas hold as endemics no less than 44% of the worlds plants and 35% of terrestrial vertebrates in an area that formerly covered only 11.8% of the planets land surface. The habitat extent of this land area had been reduced by 87.8% of its original extent, such that this wealth of biodiversity was restricted to only 1.4% of Earths land surface.

Bhutan, the northeast Indian states of West Bengal, Sikkim, Assam, and Arunachal Pradesh, southeast Tibet (China), and northern Myanmar; and the Western Himalaya, covering the Kumaon-Garhwal, northwest Kashmir, and northern Pakistan. While these divisions are largely artificial, the deep defile carved by the antecedent Kali Gandaki River between the Annapurna and Dhaulagiri mountains has been an effective dispersal barrier to many species. The abrupt rise of the Himalayan Mountains from less than 500 m to more than 8,000 m results in

Asia-Pacific has the 13 hotspots which include two of our country, namely Himalaya, and Western Ghats and Sri Lanka. To provide a glimpse of these habitats: (i) HIMALAYA: Stretching in an area over 3,000 km of northern Pakistan, Nepal, Bhutan and the northwestern and northeastern states of India, the Himalaya hotspot includes all of the worlds mountain peaks higher than 8,000 m. This includes the worlds highest mountain, Sagarmatha (Mt. Everest) as well as several of the worlds deepest river gorges. This immense mountain range, which covers nearly 750,000 km², has been divided into two regions: the Eastern Himalaya, which covers parts of Nepal,

Fig.1. Himalaya hotspot.

Table 8. Vital signs for the hotspot: Western Ghats and Sri Lanka. Hotspot Original Extent (km2) Hotspot Vegetation Remaining (km2) Endemic Plant Species

189,611 43,611 3,049

Endemic Threatened Birds

10

Endemic Threatened Mammals

14

Endemic Threatened Amphibians

87

Extinct Species+

20

Human Population Density (people/km 2) Area Protected (km ) 2

261 26,130

Area Protected (km 2) in Categories I-IV* 21,259 + Recorded extinctions since 1500. * Categories I-IV afford higher levels of protection.

Fig. 2. Western Ghats and Sri Lanka. ANU Journal of Natural Sciences w June 2010 w

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Vatsavaya et al.

Table 9. Flowering plant diversity and Endemism in India (States and Union Territories). State/Union Territory

No. of Species

Endemic Taxa

Source

1

Andaman & Nicobar Islands

2500

353

Reddy et al., 2004

2

Andhra Pradesh

2700

398

Reddy & Raju, 2008

3

Arunachal Pradesh

4204

243

Chowdhery, 1999a

4

Assam

3017

102

Baishya, 1999

5

Bihar

2650

11

Das et al., 1999

6

Chandigarh

574

0

Balodi et al., 1999

7

Dadra & Nagar Haveli

410

0

Singh & Sharma, 1999

8

Daman & Diu

404

0

Singh et al., 1999

9

Delhi

962

0

Naithani & Uniyal, 1999

10

Goa

1143

2

Singh & Kothari, 1999

11

Gujarat

2016

16

Pandey & Singh, 1999

12

Haryana

1227

0

13

Himachal Pradesh

3980

82

Chowdhery, 1999b

14

Jammu & Kashmir

4252

97

Singh et al., 1999

15

Karnataka

3849

82

Singh et al., 1999

16

Kerala

4000

344

Reddy et al., 2007

17

Lakshadweep

238

0

Bhargavan & Nair, 1999

18

Madhya Pradesh

2317

10

Verma & Mudgal, 1999

19

Maharashtra

3225

169

Karthikeyan et al., 1999

20

Manipur

2376

52

Chauhan, 1999

21

Meghalaya

3000

65

Haridasan, 1999

22

Mizoram

2141

30

Singh, 1999

23

Nagaland

2431

14

Hynniewta, 1999

24

Orissa

2630

27

Sahoo et al., 1999

25

Pondicherry

-

0

Rajan & Venu, 1999

26

Punjab

1879

4

Singh & Chauhan, 1999

27

Rajasthan

1911

22

Singh & Pandey, 1999

28

Tamil Nadu

5640

531

Chithra & Nair, 1999

29

Tripura

1546

0

Deb, 1999

30

Uttar Pradesh

4250

119

Uniyal et al., 1999

31

West Bengal

3580

7

Chakraborty et al., 1999

32

Sikkim

4500

30

Singh & Chauhan, 1999


Kumar, 1999


37

a diversity of ecosystems that range, in only a couple of hundred kilometers, from alluvial grasslands (among the tallest in the world) and subtropical broadleaf forests along the foothills to temperate broadleaf forests in the mid hills, mixed conifer and conifer forests in the higher hills, and alpine meadows above the treeline.

of rivers originate in these mountains, including the peninsulas three major eastward-flowing rivers. Thus, they are important sources of drinking water, irrigation, and power. The wide variation of rainfall patterns in the Western Ghats, coupled with the regions complex geography, produces a great variety of vegetation types. These include scrub forests in the low-lying rainshadow areas and the plains, deciduous and tropical rainforests up to about 1,500 m, and a unique mosaic of montane forests and rolling grasslands above 1,500 m.

(ii) The Western Ghats and Sri Lanka: These are in southwestern India and the highlands of southwestern Sri Lanka, separated by 400 km, are strikingly similar in their geology, climate and evolutionary history. The present account only deals with Western Ghats of India. The Western Ghats, known locally as the Sahyadri Hills, are formed by the Malabar Plains and the chain of mountains running parallel to Indias western coast, about 30 50 km inland. They cover an area of about 160,000 km² and stretch for 1,600 km from the countrys southern tip to Gujarat in the north, interrupted only by the 30 km Palghat Gap.

There are a number of minor but vital hotspots in India (Table 10) not all included in the above two major hotspots globally recognized which have to be paid deep attention to conserve the biodiversity of India, keeping in view the biogeographic zones. Acknowledgements The authors are obliged to Professor Dr K.S. Tilak, Dean, Facutly of Natural Sciences, Acharya Nagrjuna University, Nagarjunanagar, for his keen interest in the subject and encouragement.

The Western Ghats mediate the rainfall regime of peninsular India by intercepting the southwestern monsoon winds. The western slopes of the mountains experience heavy annual rainfall (with 80% of it falling during the southwest monsoon from June to September), while the eastern slopes are drier; rainfall also decreases from south to north. Dozens

References APG II : An update of the Angiosperm Phylogeny Group classification for orders and families of flowering

Table 10. The major hot spots of genetic diversity and endemic plants in India and biogeographic zones. BIOGEOGRAPHIC ZONE

HOT SPOTS

1.

Trans-Himalaya

Karakoram & Ladakh.

2.

Western Himalaya

Kumaon-Garhwal Himalaya, Siwaliks.

3.

Eastern Himalaya

Sikkim Himalaya, Arunachal Pradesh.

4.

North-East India

Lushai hills, Tura, Balphakram, Khasi hills (Meghalaya).

5.

Semi-Arid zone

Aravallis.

6.

Gangetic plain

Bundelkhand.

7.

Deccan

Chotanagpur Plateau, Panchmarhi-Satpura Ranges, SaurashtraKutch, Marathwada hills, Bastar & Koraput hills.

8.

Eastern Ghats

Simlipal & Jeypore hills of Orissa, Vishakhapatnam hills & Araku Valley, Tirupati, Cuddappa hills.

9.

Western Ghats

Mahabaleshwar-Khandala Ranges, Agumbe-Phonda Ranges, Ratnagiri & Kolaba Ranges, Nilgris, Silent Valley & Wynaad, Annamalais, Idduki-Sabarigiri, Kalakad & Agastaimalai hills. ANU Journal of Natural Sciences w June 2010 w

38

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