PLANT BIODIVERSITY- FOR MSc FINAL

PLANT BIODIVERSITY

  INTRODUCTION

A Upanishadic rhymes is

“A Guru (i.e., master) asked his disciple to bring some waste plants, thereupon the disciple goes in search of these plants and later comes only to report to his guru that he could not find a single plant which is 'waste'.”

This means that plant on earth has some value. Nature has given plenty of plant resources to human beings and he started tailoring them ever since the beginnings of civilization in manifold ways to suit his needs whether knowingly or unknowingly. The civilization of man went hand in hand with the domestication and cultivation of crop plants and their evolution took place according to the evolution of mind and thought. Millions of years, the evolution of crop plants has been taking place with the direct human agency either consciously or unconsciously.

The quest for more knowledge of plant resources continues concomitant with the rise in population and depletion of food materials. Many new plants have been added to the existing ones with the modern techniques and trends in human utilization.

Plants bring about economy to the country at large and it is a fact that the wealth of any country largely depends upon its agriculture and plant products.

In this unit, we shall review all aspect of plant diversity, sustainable development, and origin of plants and their domestication.

 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 10^th in the world and 4^th in Asia in plant diversity and ranks 11^th in the number of Angiosperm species (table 1.3). India ranks 10^th in the number of mammalian species and 11^th 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.