Plant Biodiversity
Concept and definition
Planet
Earth is endowed with a rich variety of life forms and the teeming millions of
these living organisms have been well-knit by the laws of nature. The
inter-dependence of the various life forms starting from the unicellular
primary producers to the complexly built higher plants and animals is a unique
feature of this green planet.
Bio-diversity, as this assemblage of life forms is
referred to, has now been acknowledged as the foundation for sustainable
livelihood, and food security. Scientists have estimated that more than 50
million species of plants and animals including invertebrates and
micro-organisms occur on earth and hardly 2 million of them have been described
by man so far. Scientists are also aware of the immense potentials of the
various life forms especially in the context of recent advances made in science
and technology. The incessant human assault on forests has left indelible scars
on nature. One result of the United Nations Conference on Environment and
Development held in Rio de Janerio in June 1992 was a “Convention on Biological
Diversity” which was signed by 156 countries and European community.
Definition
Biological diversity refers to the variety and
variability among living organisms and the ecological complexes in which they
occur. Diversity can be defined as the number of different items and their
relative frequency. For biological diversity, these items are organized at many
levels ranging from complete ecosystems to the chemical structures that are the
molecules basis of heredity. Thus the term encompasses different ecosystems,
species, genes and their relative abundance.
Types of Biodiversity
The term biodiversity includes three different
aspects, which are closely related to each other. Following are the types of
biodiversity:
Genetic Diversity
It refers to the variation of genes within the
species. This constitutes distinct population of the same species or genetic
variation within population or varieties within a species.
Species diversity
It refers to the variety of species within a
region. Such diversity could be measured on the basis of number of species in a
region.
Ecosystem Diversity
In an ecosystem, there may exist different
landforms, each of which supports different and specific vegetation. Ecosystem
diversity is difficult to measure since the boundaries of the communities,
which constitute the various sub ecosystems, are elusive.
Ecosystem diversity could best be understood if
one studies the communities in various ecological niches within the given
ecosystem; each community is associated with definite species complexes. These
complexes are related to composition and structure of biodiversity.
Agro-Biodiversity
The agricultural biological diversity more
commonly referred to as the agro-biodiversity has been fast emerging as a
strong, evolutionary divergent line from the biodiversity, which deals with the
life forms at large. It has been specifically recognized to differentiate
between concern for ecosystems versus agro-ecosystems, wild forest flora and
fauna versus agriculture related plants, reptiles, insects, avian and microbes;
in situ conservation of wild forms versus on farm conservation of
landgraves and traditional/ primitive cultivars or ex-situ conservation of
plant genetic resources, etc.
Agro-biodiversity in a traditional farming system
is as follows (adopted from Altieri, 1991 and UNDP, 1995):
¨
Rich
in plant and animal species
¨
A
wide diversity of niches in the local environment utilized
¨
Reuse
of organic residues, consuming biomass enabled
¨
Ecosystem
functions, such as pest, weed and disease management enhanced
¨
Locally
available resources consumed to an advantage
¨
Reduction
of risk and optimization of resources use
¨
Associated
with farmers time tested local knowledge about resources.
Biodiversity at Global Levels
It is estimated that there exists
5-30 million species of living forms on our earth and of these, only 1.5
million have been identified and include 3,00,000 species of green plants and
fungi, 8,00,000 species of insects, 40,000 species of vertebrates and 3,60,000
species of micro-organisms.
Recently it has been estimated
that the number of insects alone may be as high as 10 million, but many believe
it to be around 5 million.
The tropical forests are regarded as the riches in
biodiversity. According to the opinion of the scientists more than half of the
species on the earth live in moist tropical forests, which is only 7% of the
total land surface. Insects (80%) and primates (90%) make up most of the
species.
Table 1.1 : Estimated number of
species worldwide
|
Taxonomic Group
|
Number of Species
|
|
Bacteria
|
3600
|
|
Blue Green Algae
|
1700
|
|
Fungi
|
46983
|
|
Bryophytes
|
17000
|
|
Gymnosperms
|
750
|
|
Angiosperms
|
250000
|
Status in India
During
the last few years, the subject of conservation of biological diversity has
attracted considerable attention at the national and global levels. India is a
rich centre of biodiversity and has contributed many economic plants to the
world and many useful genes for genetic upgrading of cultivated plants and
domesticated animals.
India has a land
mass of 329 million hactares with a diversified eco-geographical regions.
Almost all types of habitats available in the world are found in India. Ther
are two biogeographical realms in India and it is the confluence of floras and faunas of
Africa, Mediterranean, European, Sino-Japanese and Malayan rgions. As a result, we have a rich
biological diversity (Gadgil, 1992).
Plant Species
diversity
At present 1.7
million species have been recorded so far in the world (Global Biodiversity,
1995). India’s contribution to this record stands at 7 %. Surveys conducted so
far have inventorised over 47,000 species of plants and over 89,000 species of
animals. Survey and inventorisation of India’s biodiversity is still far from
complete especially the lower groups of plants and invertibrate animals (Table
1.2).
Table 1.2 : India’s Biological Wealth
|
Plant Taxa
|
Species
|
Animal Taxa
|
Species
|
|
Bacteria
|
850
|
Protista
|
2577
|
|
Viruses
|
Unknown
|
Mollusca
|
5070
|
|
Algae
|
6500
|
Arthropoda
(Insecta, Crustacea etc.)
|
68389
|
|
Fungi
|
14500
|
Other Invertebrates
|
8329
|
|
Lichens
|
2000
|
Protochordata
|
119
|
|
Bryophytes
|
2850
|
Pisces
|
2546
|
|
Pteridophytes
|
1100
|
Amphibian
|
209
|
|
Gymnosperms
|
64
|
Reptilian
|
456
|
|
Angiosperms
|
17500
|
Aves
|
1232
|
|
|
|
Mammalian
|
390
|
|
Total
|
45364
|
Total
|
89317
|
Based on the available data, India ranks 10th
in the world and 4th in Asia in plant diversity and ranks 11th
in the number of Angiosperm species (table 1.3). India ranks 10th in
the number of mammalian species and 11th in the number of endemic
species of higher vertebrates in the world.
Table 1.3 : Number of angiosperm species
in different countries.
|
Country
|
Angiospermic
species
|
|
Brazil
|
55000
|
|
Colombia
|
45000
|
|
Ecuador
|
29000
|
|
China
|
27000
|
|
Mexico
|
25000
|
|
Australia
|
23000
|
|
South Africa
|
21000
|
|
Indonesia
|
20000
|
|
Venezuela
|
20000
|
|
Peru
|
20000
|
|
India
|
17000
|
Floristic status
As noted earlier
47,000 species of plants representing about 12 % of the recorded world’s flora
have already been identified. Comparative statement of recorded number of plant
species in India and the world is given in Table 1.4.
Table 1.4 :
Comparative statement of Recorded number of
plant species in India.
|
Plant Taxa
|
Species
|
Percentage of India to the World
|
|
|
India
|
World
|
||
|
Bacteria
|
850
|
4000
|
21.25
|
|
Viruses
|
Unknown
|
4000
|
-
|
|
Algae
|
6500
|
40000
|
16.25
|
|
Fungi
|
14500
|
72000
|
20.14
|
|
Lichens
|
2000
|
17000
|
11.80
|
|
Bryophytes
|
2850
|
16000
|
17.80
|
|
Pteridophytes
|
1100
|
13000
|
8.64
|
|
Gymnosperms
|
64
|
750
|
8.53
|
|
Angiosperms
|
17500
|
25000
|
7.00
|
Flowering plants
accounts nearly 17,500 among 45,000
species of plants. The important economic species includes rice, sugar cane,
coix, beans, cowpeas, banana, Citrus,
mango, coconut, cardamoms, nutmeg, tea, cotton, jute, colocasia, pepper,
ginger, Rhododendron, Jasmines,
bamboos, Orchids, betel leaf etc.
Two regions of
our country harbours maximum diversity, they are North-East and Sourth-West
India. The North- East region is a very active centre of evolution and has
diversity for a number of plants like Rhododndron,
Camelia, Magnolia, Buddleia, etc. (Khosoo, 1991).
On the basis of
distribution pattern of plants, Good (1953), divided plant wealth into 37
floristic zones. With in these zones, pockets of diversity of plants species
arose and they were domesticated by human kind during the past 10,000 years.
During these
years enormous variability was genertated because of mutation, recombination
and selection process. The result being complex variation pattern in plants.
These evolved plants bear little or no resemblance with their ancestorsss.
Endemic Species
Every major habitat, from areas of heavy rainfall
to the dry desert, from coldest to the hottest climatic conditions, from
highest elevation down to the sea level is found in the country. India has a
rich endemic flora.
Endemism of Indian biodiversity is significant.
About 4950 species of flowering plants or 33% of this recorded flora are endemic
to the country. These are distributed over 141 genera belonging to 47 families.
These are concentrated in the floristically rich areas of North-East India, the
Western Ghats, North-West Himalayas and the Andaman & Nicobar Islands.
The Western Ghats and Eastern Himalayas are
reported to have 16000 and 3500 endemic species of flowering plants,
respectively. These areas constitute two of the 34 hot spots identified in the
world.
Cultivated
plants
Indian region alone has given to the world nearly
167 economical plants whose centre of origin/ diversity lie in India along with
their 320 species of wild relatives and land races.
India is considered to be the centre of origin of
rice, sugar cane, minor millets, pigeon pea, brassicas, rice-bean, Asiatic
vignas, egg plant, banana, citrus, mango, cardamom, jack fruit, jute, edible
diascorea, black pepper, seed amaranths, turmeric, ginger, several umbellifers
and cucurbits, bittergourd, colacasia, okra, coconut, bamboo, taro, indigo, sun
hemp, gooseberries and many herbal drugs, rhododendron, jasmine, some orchids
and betel nut. This remarkable diversity of life-forms in a single country is
because of the great diversity of ecosystems.
The gene bank of National Bureau of Plant Genetic
Resources (NBPGR) has a collection of over 1,59,080 varieties. The details of
the active germplasm holding and base collections of NBPGR are given in Table
1.5.
Table 1.5 : Active germplasm holding and
base collections at NBPGR.
|
Crop groups
|
Active
germplasm
|
Base collection holdings
|
|
Cereals
|
12086
|
43409
|
|
Pulses
|
38695
|
22269
|
|
Millets & Minor Millets
|
10349
|
14488
|
|
Oilseeds
|
19808
|
14278
|
|
Vegetables
|
12146
|
5681
|
|
Medicinal & Aromatic Plants
|
870
|
942
|
|
Pseudocereals
|
4739
|
736
|
|
Tuber Crop/ Spices
|
2053
|
-
|
|
Forage Crop
|
4060
|
-
|
|
Horticultural/ Ornamentals
|
22212
|
-
|
|
Fibre Crops
|
-
|
3212
|
|
Released crop Varieties
|
-
|
904
|
|
Reference Samples
(Medium Term)
|
-
|
53161
|
|
Total
|
107018
|
159080
|
Wild relatives
of Crops
There are several hundred species of wild crop
relatives distributed all over the country. A major centre for wild rice is the
eastern peninsular India, i.e., West Bengal, Orissa and Andhra Pradesh. The
North-Eastern hills and Tamil Nadu hills are rich in wild relatives of millets.
Wild relatives of wheat and barley have been located in the western and
North-Eastern Himalaya. Table 1.6 gives the statement of wild relatives of
crops recorded so far.
Table 1.6 : Wild relatives of crop
|
Crop
|
No. of
Wild relatives
|
|
Millets
|
51
|
|
Fruits
|
104
|
|
Spices and condiments
|
27
|
|
Vegetables and pulses
|
55
|
|
Fibre crop
|
24
|
|
Oil seeds, tea, coffee,
tobacco, & sugarcane
|
12
|
|
Medicinal plants
|
3000
|
Utilization of plant biodiversity
Biological resources contribute much to the social
and economical development of the nation. Utilizing the species for industry
and medicine and developing new products for national and international market
provides good opportunities. Greater agricultural production and prevention of
diseases and pests are also important. Biological and genetic diversity are
fundamental to the proper functioning of any ecosystem and hence to human
welfare.
The most important contribution of the earth’s
biota is to maintain the ecosystem ability to provide essential life support
functions, e.g. fixation of solar energy. Genetic resources are most precious
asset. They are nature’s tool for harvesting solar energy and processing
mineral resources in to food, fibre, fertilizer etc. They are crucial for human
survival in the physical environment. They are the result of evolution over
million of years.
Biological resources are active entities and
extremely vulnerable. Once they are lost, they can not be replaced at any cost.
Success of genetic engineering depends upon genes
(the basic building blocks) from plants, animals and micro-organisms.
Therefore, ensuring success in genetic engineering, we need to conserve
biological resources.
Genetic diversity is heritable with in and between
of the species of a genus. Genetic diversity is very critical to our
agriculture, horticulture, forestry and animal husbandry. Many germplasms from
India have made many distinctive contributions in plant improvement. Broadly
speaking biological diversity satisfies human needs in two different ways,
direct and indirect.
Biodiversity will not only help in increasing
agricultural productivity but also in developing disease resistant varieties.
It was evident in the early 1970’s when epidemic called grassy stunt virus
destroyed more than 1,60,000 ha of rice in Asia, could be controlled from a
single sample of wild rice Oryza nivara from Central India, which was found to be the
only known genetic source of resistance to the grassy stunt. Besides 20 major
genes from wild for disease and pest resistance are used in rice improvement
programmes.
Besides food and other basic needs, human health
has gained priority in welfare programmes. Once all medicines used to come from
plant and animal resources. Worldwide medicines from plants are now worth 40
billion dollars a years. Even now 80 percent people in the developing countries
depend upon traditional medicines.
Indirect benefits include nutrient trapping,
maintaining water cycles, soil production and protection of soil, absorption
and break down of pollutants, provision of recreational, aesthetic, scientific,
spiritual etc.
It is estimated that more than 25 percent of all
medicines available today are derived from tropical plants. Over 40 percent of
Pharmaceuticals available in the USA depend on natural sources.
In 1960, a child contracting Leukemia had one
chance in five survival, since then scientists have developed a drug –
Vincristine from a plant of the tropical forests, Vinca rosea, that now allow
leukemia sufferer four chances in five of survival.
The National Cancer Institute near Washington DC
has screened 29,000 plant species, and at least five may come to rival
vincristine. The institute believes that mass extinctions of species could
represent a serious back to the future of anti-cancer campaigns.
Among other medical products the “pill” that is
swallowed by million women each day contains sex hormone combination derive
from a Mexican forest yam. Over-the-counter sales of the pill are re worth one
million dollar a year.
Prioritization
approach and patenting
The list of species to be conserved is
ever-increasing. There are also other
plants and animals, which are likely to be important in future. There is a
whole range of threatened/ endangered plants numbering around 2000 in India.
Resource constraints do not allow, all these to be saved and it would be
totally unrealistic even to attempt this.
Approach of prioritization, both of economic
importance and academic interest are needed. With in a country different states
could select an indigenous mammal, bird, wild flower and a tree. These could
then be declared as state mammal, bird, flower and tree. Rajasthan state has
declared Great Indian Bustard (Ardeotis nigriceps) as state bird and
Khejri (Prosopis cineraria) as state tree. Based on indepth study, an
agreed list of species could be arrived and the best way of conservation
method(s) to b employed.
Patents are meant to stimulate innovation and
increase public perception about new ideas and inventions. A patent is,
therefore, a limited monopoly for a given number of years during which patentee
has exclusive rights to the invention. In view of expanding role of “Genetic
raw materials” is genetic engineering, patenting of cultivars by multinationals
has to be looked in a proper manner. During patenting, legal, economical and
technical issues may be taken into account.
Each country needs to critically review their
network of conservation areas, together with their future plans. The
conservation of just wild animals alone will not succeed unless, the carefully
chosen ecosystem need to be taken up for conservation purpose. Special
attention must be paid to forests having large biological diversity of plants
and animals.
Biological diversity has become a sensitive
subject. Countries having biodiversity needs to adopt a code of conduct and has
to conserve the diversity for sustainable use for the future generations.
National network for the management of protected
areas with clearly specified inter-connections are required. There is a need
for long range, land use planning of the protected areas. The management plan
must be science and technology based and it should to be over-exploitation. To
accomplish such an obligation necessary legislative and scientific steps should
be taken for the survival, regulation and conservation of threatened species.
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