UNIT II
Ecosystem
An ecosystem is a biotic community together with its physical environment, considered as an
integrated unit. Implied within this definition is the concept of a structural and functional whole
unified through life processes. An ecosystem may be characterized as a viable unit of
community and interactive habitat. Ecosystems are hierarchical and can be viewed as nested
sets of open systems in which physical, chemical, and biological processes form interactive
subsystems. Some ecosystems are microscopic and the largest comprises the biosphere.
Ecosystem restoration can be directed at different-sized ecosystems within the nested set, and
many encompass multiple states, more localized watersheds, or a smaller complex of aquatic
habitat.
ECOLOGY :
1.a. The science of the relationships between organisms and their environments. Also called bionomics.
b. The relationship between organisms and their environment.
2. The branch of sociology that is concerned with studying the relationships between human groups and
their physical and social environments. Also called human ecology.
INTRODUCTION :
The entire array of organisms inhabiting a particular ecosystem is called a community.[1] In a
typical ecosystem, plants and other photosynthetic organisms are the producers that provide the
food.[1] Ecosystems can be permanent or temporary. Ecosystems usually form a number of food
webs.[2]
Ecosystems are functional units consisting of living things in a given area, non-living chemical
and physical factors of their environment, linked together through nutrient cycle and energy
flow.[citation needed]
1. Natural
1. Terrestrial ecosystem
2. Aquatic ecosystem
1. Lentic, the ecosystem of a lake, pond or swamp.
2. Lotic, the ecosystem of a river, stream or spring.
2. Artificial, ecosystems created by humans.
Central to the ecosystem concept is the idea that living organisms interact with every other
element in their local environment. Eugene Odum, a founder of ecology, stated: "Any unit that
includes all of the organisms (ie: the "community") in a given area interacting with the physical
environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity,
and material cycles (i.e.: exchange of materials between living and nonliving parts) within the
system is an ecosystem."[3]
Etymology
The term ecosystem was coined in 1930 by Roy Clapham to mean the combined physical and
biological components of an environment. British ecologist Arthur Tansley later refined the term,
describing it as "The whole system, … including not only the organism-complex, but also the
whole complex of physical factors forming what we call the environment".[4] Tansley regarded
ecosystems not simply as natural units, but as mental isolates.[4] Tansley later[5] defined the
spatial extent of ecosystems using the term ecotope.
Examples of ecosystems
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Agroecosystem
Aquatic ecosystem
Chaparral
Coral reef
Desert
Forest
Greater Yellowstone Ecosystem
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Human ecosystem
Large marine ecosystem
Littoral zone
Lotic
Marineecosystem
Pond ecosystem
Biomes
Map of Terrestrial biomes classified by vegetation.
: Biome
Biomes are a classification of globally similar areas, including ecosystems, such as ecological
communities of plants and animals, soil organisms and climatic conditions.[citation needed] Biomes
are in part defined based on factors such as plant structures (such as trees, shrubs and grasses),
leaf types (such as broadleaf and needleleaf), plant spacing (forest, woodland, savanna) and
climate.[citation needed] Unlike ecozones, biomes are not defined by genetic, taxonomic or historical
similarities. Biomes are often identified with particular patterns of ecological succession and
climax vegetation.
A fundamental classification of biomes is:
1. Terrestrial (land) biomes.
2. Freshwater biomes.
3. Marine biomes.
Classification
Summer field in Belgium (Hamois). The blue flower is Centaurea cyanus and the red one a Papaver
rhoeas.
The High Peaks Wilderness Area in the 6,000,000-acre (2,400,000 ha) Adirondack Park is an example of a
diverse ecosystem.
Flora of Baja California Desert, Cataviña region, Mexico.
Ecosystems have become particularly important politically, since the Convention on Biological
Diversity (CBD) - ratified by 192 countries - defines "the protection of ecosystems, natural
habitats and the maintenance of viable populations of species in natural surroundings"[6] as a
commitment of ratifying countries. This has created the political necessity to spatially identify
ecosystems and somehow distinguish among them. The CBD defines an "ecosystem" as a
"dynamic complex of plant, animal and micro-organism communities and their non-living
environment interacting as a functional unit".
With the need of protecting ecosystems, the political need arose to describe and identify them
efficiently. Vreugdenhil et al. argued that this could be achieved most effectively by using a
physiognomic-ecological classification system, as ecosystems are easily recognizable in the field
as well as on satellite images. They argued that the structure and seasonality of the associated
vegetation, or flora, complemented with ecological data (such as elevation, humidity, and
drainage), are each determining modifiers that separate partially distinct sets of species. This is
true not only for plant species, but also for species of animals, fungi and bacteria. The degree of
ecosystem distinction is subject to the physiognomic modifiers that can be identified on an image
and/or in the field. Where necessary, specific fauna elements can be added, such as seasonal
concentrations of animals and the distribution of coral reefs.
CLASSIFICATION OF ECOSYSTEM
An ecosystem can be classified as below
ECOSYSTEM
NATURAL ECOSYSTEM
i)
ARTIFICIAL ECOSYSTEM
TERRESTRIAL ECOSYSTEM
Forests
Grasslands
Deserts
ii)
AQUATIC ECOSYSTEM
Fresh Waters
Marine Waters
There are further classifications in the above chart, but for a beginner level, it is enough to
concentrate on these areas. Also the study of artificial ecosystem is not the scope of an
environmental scientist. The environmentalists deal with natural creations and management only.
Moreover the system in artificial ecosystem does not offer much to study. Therefore we are more
interested in natural ecosystem and don’t consider artificial ecosystem
STRUCTURE OF ECOSYSTEM
By Architecture or Structure of an Ecosystem, we mean
the composition of biological community including species, numbers,
biomass, life history and distribution in space, etc.
the quantity and distribution of non living materials like nutrients, water etc.
the conditions of existence such as temperature, light etc.
An ecosystem possesses both living components and biotic factors and nonliving
or abiotic factors.
The nonliving factors, called abiotic factors, are physical and chemical characteristics of the
environment. They include solar energy (amount of sun light), oxygen, CO2, water, temperature,
humidity, ph, and availability of nitrogen.
The living components of the environment are called Biotic Factors. They include all the Living
Things that affect an organism. Biotic Components are often categorized as Producers, Consumers,
and Decomposer.
FUNCTION OF AN ECOSYSTEM
The function of an ecosystem is a broad, vast and often confused topic. The function of an
ecosystem can be best studied by understanding the history of ecological studies. The function of an
ecosystem can be studied under the three heads
.
1. Trophic Level Interaction
2.
Ecological Succession
3. Biogeochemistry
Trophic Level Interaction deals with how the members of an ecosystem are connected
based on nutritional needs. Ecological Succession deals with the changes in features/members of
an ecosystem over a period of time. Biogeochemistry is focussed upon the cycling of essential
materials in an ecosystem.
As we would be discussing about ecological succession and bio geo chemistry in the future
chapters, we shall confine to Trophic level interaction alone in this chapter. For examination
purposes, the student may also stop with explaining the constituents of trophic level interaction
.
Trophic Level Interaction was developed by zoologist Charles Elton. It deals with who eats
who and is eaten by whom in an ecosystem. The study of trophic level interaction in an ecosystem
gives us an idea about the energy flow through the ecosystem
.
The trophic level interaction involves three concepts namely
1. Food Chain
2. Food Web
3. Ecological Pyramids
FOOD CHAIN
In an ecosystem one can observe the transfer or flow of energy from one trophic level to other in
succession. A trophic level can be defined as the number of links by which it is separated from the
producer, in the food chain. The patterns of eating and being eaten forms a linear chain called food
chain which can always be traced back to the producers. Thus, primary producers trap radiant
energy of sun and transfer that to chemical or potential energy of organic compounds such as
carbohydrates, proteins and fats.
When a herbivore animal eats a plant (or when bacteria decompose it) and these organic
compounds are oxidized, the energy liberated is just equal to the amount of energy used in
synthesizing the substances (first law of thermodynamics), but some of the energy is heat and not
useful energy (second law of thermodynamics). If this animal, in rum, is eaten by another one, along
with transfer of energy from a herbivore to carnivore a further decrease in useful energy occurs as
the second animal (carnivore) oxidizes the organic substances of the first (herbivore or omnivore) to
liberate energy to synthesize its own cellular constituents. Such transfer of energy from organism to
organism sustains the ecosystem and when energy is transferred from individual to individual in a
particular community, as in a pond or a lake or a river, we come across the food chains. The number
of steps in a food chain are always restricted to four or five, since the energy available decreases
with each step. Many direct or indirect methods arc employed to study food chain relationships in
nature. They include gut content analysis, use of radioactive isotopes, precipitin test, etc.
Chain Diagram
A simple, nice, clear diagram showing you the Food Chain. The diagram is useful for
anyone interested in learning about Food Chains. We hope you like the Food Chain
Diagrams and Layouts displayed on this site below.
Diagram, Chart & Layout Site
FOOD WEB
food web is a graphical description of feeding relationships among species in an ecological
community, that is, of who eats whom (Fig. 1). It is also a means of showing how energy and
materials (e.g., carbon) flow through a community of species as a result of these feeding
relationships. Typically, species are connected by lines or arrows called "links", and the species
are sometimes referred to as "nodes" in food web diagrams.
Figure 1. A coastal food web in Alaska based on primary production by phytoplankton, and ending in
predators of both land and sea. (Image courtesy U.S. Geological Survey)
The pioneering animal ecologist Charles Elton (1927) introduced the concept of the food web
(which he called food cycle) to general ecological science. As he described it: "The herbivores
are usually preyed upon by carnivores, which get the energy of the sunlight at third-hand, and
these again may be preyed upon by other carnivores, and so on, until we reach an animal which
has no enemies, and which forms, as it were, a terminus on this food cycle. There are, in fact,
chains of animals linked together by food, and all dependent in the long run upon plants. We
refer to these as 'food-chains', and to all the food chains in a community as the 'food-cycle.'"
A food web differs from a food chain in that the latter shows only a portion of the food web
involving a simple, linear series of species (e.g., predator, herbivore, plant) connected by feeding
links. A food web aims to depict a more complete picture of the feeding relationships, and can be
considered a bundle of many interconnected food chains occurring within the community. All
species occupying the same position within a food chain comprise a trophic level within the food
web. For instance, all of the plants in the foodweb comprise the first or "primary producer" tropic
level, all herbivores comprise the second or "primary consumer" trophic level, and carnivores
that eat herbivores comprise the third or "secondary consumer" trophic level. Additional levels,
in which carnivores eat other carnivores, comprise a tertiary trophic level.
Ecological pyramid
An ecological pyramid (also trophic pyramid or energy pyramid) is a graphical representation
designed to show the biomass or biomass productivity at each trophic level in a given ecosystem.
Biomass is the amount of living or organic matter present in an organism. Biomass pyramids
show how much biomass is present in the organisms at each trophic level, while productivity
pyramids show the production or turnover in biomass.
Ecological pyramids begin with producers on the bottom (such as plants) and proceed through
the various trophic levels (such as herbivores that eat plants, then carnivores that eat herbivores,
then carnivores that eat those carnivores, and so on). The highest level is the top of the food
chain.
Contents
[hide]
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1 Pyramid of biomass
2 Pyramid of productivity
3 Pyramid of numbers
[edit] Pyramid of biomass
An ecological pyramid of biomass shows the relationship between biomass and trophic level by
quantifying the amount of biomass present at each trophic level of an ecological community at a
particular moment in time. Typical units for a biomass pyramid could be grams per meter2, or
calories per meter2.
The pyramid of biomass may be 'inverted'. For example, in a pond ecosystem, the standing crop
of phytoplankton, the major producers, at any given point will be lower than the mass of the
heterotrophs, such as fish and insects. This is explained as the phytoplankton reproduce very
quickly, but have much shorter individual lives.
One problem with biomass pyramids is that they can make a trophic level look like it contains
more energy than it actually does. For example, all birds have beaks and skeletons, which despite
taking up mass are not eaten by the next trophic level. In a pyramid of biomass the skeletons and
beaks would still be quantified even though they do not contribute to the overall flow of energy
when ripping and tearing into the next trophic level.
[edit] Pyramid of productivity
An ecological pyramid of productivity is often more useful, showing the production or turnover
of biomass at each trophic level. Instead of showing a single snapshot in time, productivity
pyramids show the flow of energy through the food chain. Typical units would be grams per
meter2 per year or calories per meter2 per year. As with the others, this graph begins with
producers at the bottom and places higher trophic levels on top.
When an ecosystem is healthy, this graph produces a standard ecological pyramid. This is
because in order for the ecosystem to sustain itself, there must be more energy at lower trophic
levels than there is at higher trophic levels. This allows for organisms on the lower levels to not
only maintain a stable population, but to also transfer energy up the pyramid. The exception to
this generalization is when portions of a food web are supported by inputs of resources from
outside of the local community. In small, forested streams, for example gone up greater than
could be supported by the local primary production.
When energy is transferred to the next trophic level, typically only 10%[citation needed] of it is used
to build new biomass, becoming stored energy (the rest going to metabolic processes). As such,
in a pyramid of productivity each step will be 10% the size of the previous step (100, 10, 1, 0.1,
0.01)[citation needed].
[edit] Pyramid of numbers
An ecological pyramid of numbers shows graphically the population of each level in a food
chain.
The diagram to the right shows a (nonfictional) example of a five level pyramid of numbers:
10,000 fresh water shrimps support 1,000 bleak, which in turn support 100 perches followed by
10 northern pikes and finally one osprey.
Carbon cycle
All living organisms are made up of molecules that contain carbon: carbo-hydrates, proteins and
lipids.
The carbon cycle includes all the reactions that allow living organisms to use carbon to
manufacture their tissues and release energy.
Plants are the starting point of the carbon cycle. Through the process of photosynthesis, plants
absorb carbon from the air (CO2) and incorporate it into their biomass (leaves, wood, roots,
flowers, fruits). This organic matter provides food for heterotrophic organisms (consumers). By
releasing energy when they respire, heterotrophs and autotrophs return carbon to the atmosphere
(CO2).
NITROGENCYCLE
The processes of the nitrogen cycle
Nitrogen is present in the environment in a wide variety of chemical forms including organic
nitrogen, ammonium (NH4+), nitrite (NO2-), nitrate (NO3-), and nitrogen gas (N2). The organic
nitrogen may be in the form of any living organism, or humus, and in the intermediate products
of organic matter decomposition or humus built up. The processes of the nitrogen cycle
transform nitrogen from one chemical form to another. Many of the processes are carried out by
microbes either to produce energy or to accumulate nitrogen in the form needed for growth. The
diagram above shows how these processes fit together to form the nitrogen cycle.
[edit] Nitrogen fixation
Main article: Nitrogen fixation
Atmospheric nitrogen must be processed, or "fixed" (see page on nitrogen fixation), to be used
by plants. Some fixation occurs in lightning strikes, but most fixation is done by free-living or
symbiotic bacteria. These bacteria have the nitrogenase enzyme that combines gaseous nitrogen
with hydrogen to produce ammonia, which is then further converted by the bacteria to make their
own organic compounds. Most biological nitrogen fixation occurs by the activity of Monitrogenase, found in a wide variety of bacteria and some Archaea. Mo-nitrogenase is a complex
two component enzyme that contains multiple metal-containing prosthetic groups.[4] Some
nitrogen fixing bacteria, such as Rhizobium, live in the root nodules of legumes (such as peas or
beans). Here they form a mutualistic relationship with the plant, producing ammonia in exchange
for carbohydrates. Nutrient-poor soils can be planted with legumes to enrich them with nitrogen.
A few other plants can form such symbioses. Today, about 30% of the total fixed nitrogen is
manufactured in ammonia chemical plants.[5]
] Conversion of N2
The conversion of nitrogen (N2) from the atmosphere into a form readily available to plants and
hence to animals and humans is an important step in the nitrogen cycle, which distributes the
supply of this essential nutrient. There are four ways to convert N2 (atmospheric nitrogen gas)
into more chemically reactive forms:[2]
1. Biological fixation: some symbiotic bacteria (most often associated with leguminous plants) and
some free-living bacteria are able to fix nitrogen as organic nitrogen. An example of mutualistic
nitrogen fixing bacteria are the Rhizobium bacteria, which live in legume root nodules. These
species are diazotrophs. An example of the free-living bacteria is Azotobacter.
2. Industrial N-fixation: Under great pressure, at a temperature of 600 C, and with the use of an
iron catalyst, atmospheric nitrogen and hydrogen (usually derived from natural gas or
petroleum) can be combined to form ammonia (NH3). In the Haber-Bosch process, N2 is
converted together with hydrogen gas (H2) into ammonia (NH3), which is used to make fertilizer
and explosives.
3. Combustion of fossil fuels: automobile engines and thermal power plants, which release various
nitrogen oxides (NOx).
4. Other processes: In addition, the formation of NO from N2 and O2 due to photons and especially
lightning, can fix nitrogen.
Assimilation
Plants get nitrogen from the soil, by absorption of their roots in the form of either nitrate ions or
ammonium ions. All nitrogen obtained by animals can be traced back to the eating of plants at
some stage of the food chain.
Plants can absorb nitrate or ammonium ions from the soil via their root hairs. If nitrate is
absorbed, it is first reduced to nitrite ions and then ammonium ions for incorporation into amino
acids, nucleic acids, and chlorophyll.[2] In plants that have a mutualistic relationship with
rhizobia, some nitrogen is assimilated in the form of ammonium ions directly from the nodules.
Animals, fungi, and other heterotrophic organisms obtain nitrogen as amino acids, nucleotides
and other small organic molecules.
] Ammonification
When a plant or animal dies, or an animal expels waste, the initial form of nitrogen is organic.
Bacteria, or fungi in some cases, convert the organic nitrogen within the remains back into
ammonium (NH4+), a process called ammonification or mineralization. Enzymes Involved:
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GS: Gln Synthetase (Cytosolic & PLastid)
GOGAT: Glu 2-oxoglutarate aminotransferase (Ferredoxin & NADH dependent)
GDH: Glu Dehydrogenase:
o Minor Role in ammonium assimilation.
o Important in amino acid catabolism.
] Nitrification
The conversion of ammonium to nitrate is performed primarily by soil-living bacteria and other
nitrifying bacteria. The primary stage of nitrification, the oxidation of ammonium (NH4+) is
performed by bacteria such as the Nitrosomonas species, which converts ammonia to nitrites
(NO2-). Other bacterial species, such as the Nitrobacter, are responsible for the oxidation of the
nitrites into nitrates (NO3-).[2]It is important for the nitrites to be converted to nitrates because
accumulated nitrites are toxic to plant life.
Due to their very high solubility, nitrates can enter groundwater. Elevated nitrate in groundwater
is a concern for drinking water use because nitrate can interfere with blood-oxygen levels in
infants and cause methemoglobinemia or blue-baby syndrome.[6] Where groundwater recharges
stream flow, nitrate-enriched groundwater can contribute to eutrophication, a process leading to
high algal, especially blue-green algal populations and the death of aquatic life due to excessive
demand for oxygen. While not directly toxic to fish life like ammonia, nitrate can have indirect
effects on fish if it contributes to this eutrophication. Nitrogen has contributed to severe
eutrophication problems in some water bodies. As of 2006, the application of nitrogen fertilizer
is being increasingly controlled in Britain and the United States. This is occurring along the same
lines as control of phosphorus fertilizer, restriction of which is normally considered essential to
the recovery of eutrophied waterbodies.
Denitrification is the reduction of nitrates back into the largely inert nitrogen gas (N2),
completing the nitrogen cycle. This process is performed by bacterial species such as
Pseudomonas and Clostridium in anaerobic conditions.[2] They use the nitrate as an electron
acceptor in the place of oxygen during respiration. These facultatively anaerobic bacteria can
also live in aerobic conditions.
] Anaerobic ammonium oxidation
In this biological process, nitrite and ammonium are converted directly into elemental nitrogen
(N2) gas. This process makes up a major proportion of elemental nitrogen conversion in the
oceans.
PHOSPHOROUS CYCLE
Process of the cycle
Phosphates move quickly through plants and animals; however, the processes that move them
through the soil or ocean are very slow, making the phosphorus cycle overall one of the slowest
biogeochemical cycles.
Unlike other cycles of matter compounds, phosphorus cannot usually be found in air as a gas, it
only occurs under highly reducing conditions as the gas Phosphine PH3. This is because at
normal temperature and circumstances, it is a solid in the form of red and white phosphorus. It
usually cycles through water, soil and sediments. Phosphorus is typically the limiting nutrient
found in streams, lakes and fresh water environments. As rocks and sediments gradually wear
down, phosphate is released. In the atmosphere phosphorus is mainly small dust particles.
Initially, phosphate weathers from rocks. The small losses in a terrestrial system caused by
leaching through the action of rain are balanced in the gains from weathering rocks. In soil,
phosphate is absorbed on clay surfaces and organic matter particles and becomes incorporated
(immobilized). Plants dissolve ionized forms of phosphate. Herbivores obtain phosphorus by
eating plants, and carnivores by eating herbivores. Herbivores and carnivores excrete phosphorus
as a waste product in urine and feces. Phosphorus is released back to the soil when plants or
animal matter decomposes and the cycle repeats.
FOREST ECOSYSTEM
GRASSLAND ECOSYSTEM
DESERT ECOSYSTEM
AQUATIC ECOSYSTEM
POND ECOSYSTEM
LAKE ECOSYSTEM
RIVER ECOSYSTEM
ESTURINE ECOSYSTEM
OCEAN ECOSYSTEM
BIODIVERSITY
DEFINITION :
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or
an entire planet. Biodiversity is a measure of the health of ecosystems. Greater biodiversity
implies greater health. Biodiversity is in part a function of climate. In terrestrial habitats, tropical
regions are typically rich whereas polar regions support fewer species.
LOSS OF BIODIVERSITY :
Habitat loss and degradation
Climate change
Excessive nutrient load and other forms of pollution
Over-exploitation and unsustainable use
Invasive alien species
Genetic diversity
Genetic diversity, the level of biodiversity, refers to the total number of genetic characteristics
in the genetic makeup of a species. It is distinguished from genetic variability, which describes
the tendency of genetic characteristics to vary.
Genetic diversity serves as a way for populations to adapt to changing environments. With more
variation, it is more likely that some individuals in a population will possess variations of alleles
that are suited for the environment. Those individuals are more likely to survive to produce
offspring bearing that allele. The population will continue for more generations because of the
success of these individuals.[1]
The academic field of population genetics includes several hypotheses and theories regarding
genetic diversity. The neutral theory of evolution proposes that diversity is the result of the
accumulation of neutral substitutions. Diversifying selection is the hypothesis that two
subpopulations of a species live in different environments that select for different alleles at a
particular locus. This may occur, for instance, if a species has a large range relative to the
mobility of individuals within it. Frequency-dependent selection is the hypothesis that as alleles
become more common, they become more vulnerable. This is often invoked in host-pathogen
interactions, where a high frequency of a defensive allele among the host means that it is more
likely that a pathogen will spread if it is able to overcome that allele.
Species diversity
Species diversity is an index that incorporates the number of species in an area and also their
relative abundance. It is a more comprehensive value than species richness.[1]
The most common index of species diversity is a family of equations called Simpson's Diversity
Index.[2]
Humans have a huge effect on species diversity; the main reasons are:
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Destruction, modification and fragmentation of habitat
Introduction of exotic species
Overharvesting
Global climate change
COMMUNITY DIVERSITY
1.
Diversity invigorates problem solving. Science benefits greatly
from a community that approaches problems in a variety of
creative ways.
VALUES OF BIODIVERSITY
The value of biodiversity is classified into direct and indirect values as shown in the below diagram.
Values of
biodiversity
Direct values
Consumptive
use values
Productive
use values
Indirect
values
Social and
cultural
values
Ethical
values
Aesthetic
values
Option
values
Environment
service values
Direct values
The direct value include food resources like grains, vegetables, fruits which are obtained from plant resources
and meat, fish, egg, milk and milk products from animal resources. These also include other values like
medicine, fuel, timber, fiber, wool, wax, resin, rubber, silk and decorative items.
The direct values are of two types (i) Consumptive use value and (ii) Productive use value.
Consumptive use value: These are the direct use values where the biodiversity products can be harvested
and consumed directly. Example: Food, fuel and drugs. These goods are consumed locally and do no figure
in national and international market.
(a)
Food:
(i) Plants: The most fundamental value of biological resources particularly plants is providing food.
Basically three crops i.e. wheat, maize and rice constitute more than two third of the food requirement all
over the world.
(ii) Fish: Through the development of aquaculture, techniques, fish and fish products have become the
largest source of protein in the world.
(b)
Fuel: Since ages forests have provided wood which is used as a fuel. Moreover fossil fuels like coal,
petroleum, natural gas are also product of biodiversity which are directly consumed by humans.
(c)
Drugs and medicines: The traditional medical practice like ayurveda utilizes plants or their extracts
directly. In allopathy, the pharmaceutical industry is much more dependent on natural products. Many
drugs are derived from plants like
(i)
Quinine: The famous anti malaria drug is obtained from cinchona tree.
(ii)
Penicillin: A famous antibiotic is derived from pencillium, a fungus.
(iii)
Tetracycline: It is obtained from bacterium.
(iv)
Recently vinblastin and vincristine, two anti cancer drugs have been obtained from
catharanthus plant which has anti cancer alkaloids.
Productive use values: These are the direct use values where the product is commercially sold in national
and international market. Many industries are dependent upon these values. Example- Textile, leather, silk,
paper and pulp industry etc. Although there is an international ban on trade of products from endangered
species like tusks of elephants, wool from sheep, fur of many animals etc. These are traded in market and
fetch a booming business.
Indirect values
Biodiversity provides indirect benefits to human beings which support the existence of biological life and other
benefits which are difficult to quantify. These include social and cultural values, ethical values, aesthetic
values, option values and environment service values.
Social and cultural value: Many plants and animals are considered holy and sacred in India and are
worshipped like Tulsi, peepal, cow, snake etc. In Indian society great cultural value is given to forest and as
such tiger, peacock and lotus are named as the national animal, bird and flower respectively.
Ethical: These values are related to conservation of biodiversity where ethical issue of ‘all life forms must be
preserved’ is laid down. There is an existence value which is attached to each species because biodiversity is
valuable for the survival of human race. Moreover all species have a moral right to exist independent of our
need for them.
Aesthetic value: There is a great aesthetic value which is attached to biodiversity. Natural landscapes at
undisturbed places are a delight to watch and also provide opportunities for recreational activities like bird
watching, photography etc. It promotes eco-tourism which further generates revenue by designing of
zoological, botanical gardens, national parks, wild life conservation etc.
Option values: These values include the unexplored or unknown potentials of biodiversity.
Environment service values: The most important benefit of biodiversity is maintenance of environment
services which includes
(i)
(ii)
Carbon dioxide fixation through photosynthesis.
Maintaining of essential nutrients by carbon (C), oxygen (O), Nitrogen (N), Sulphur (S),
Phosphorus (P) cycles.
(iii)
Maintaining water cycle and recharging of ground water.
(iv)
Soil formation and protection from erosion.
(v)
Regulating climate by recycling moisture into the atmosphere.
(vi)
Detoxification and decomposition of waste.
© 2008 Enviromatter.com. All rights reserved.
Hotspots
A biodiversity hotspot is a region with a high level of endemic species. Hotspots were first
named in 1988 by Dr. Norman Myers.[25][26] Many hotspots have large nearby human
populations.[27] While hotspots are spread all over the world, the majority are forest areas and
most are located in the tropics.[28]
Brazil's Atlantic Forest is considered one such hotspot, containing roughly 20,000 plant species,
1,350 vertebrates, and millions of insects, about half of which occur nowhere else. The island of
Madagascar, particularly the unique Madagascar dry deciduous forests and lowland rainforests,
possess a high ratio of endemism. Since the island separated from mainland Africa 65 million
years ago, many species and ecosystems have evolved independently. Indonesia's 17,000 islands
cover 735,355 square miles (1,904,560 km2) contain 10% of the world's flowering plants, 12% of
mammals and 17% of reptiles, amphibians and birds—along with nearly 240 million people.[29]
Many regions of high biodiversity and/or endemism arise from specialized habitats which require
unusual adaptations, for example alpine environments in high mountains, or Northern European
peat bogs.
Accurately measuring differences in biodiversity can be difficult. Selection bias amongst
researchers may contribute to biased empirical research for modern estimates of biodiversity. In
1768 Rev. Gilbert White succinctly observed of his Selborne, Hampshire "all nature is so full,
that that district produces the most variety which is the most examined."[30]
Species loss rates
During the last century, decreases in biodiversity have been increasingly observed. In 2007,
German Federal Environment Minister Sigmar Gabriel cited estimates that up to 30% of all
species will be extinct by 2050.[75] Of these, about one eighth of known plant species are
threatened with extinction.[76] Estimates reach as high as 140,000 species per year (based on
Species-area theory).[77] This figure indicates unsustainable ecological practices, because few
species emerge each year.[citation needed] Almost all scientists acknowledge that the rate of species
loss is greater now than at any time in human history, with extinctions occurring at rates
hundreds of times higher than background extinction rates.[76]
Threats
Jared Diamond describes an "Evil Quartet" of habitat destruction, overkill, introduced species,
and secondary extinctions.[78] Edward O. Wilson prefers the acronym HIPPO, standing for
habitat destruction, invasive species, pollution, human over population, and overharvesting.[79][80] The most authoritative classification in use today is IUCN’s Classification of
Direct Threats[81] which has been adopted by major international conservation organizations such
as the US Nature Conservancy, the World Wildlife Fund, Conservation International, and
Birdlife International.
] Habitat destruction
Deforestation and increased road-building in the Amazon Rainforest are a significant concern because of
increased human encroachment upon wild areas, increased resource extraction and further threats to
biodiversity.
Habitat destruction
Habitat destruction has played a key role in extinctions, especially related to tropical forest
destruction.[82] Factors contributing to habitat loss are: overpopulation, deforestation,[83] pollution
(air pollution, water pollution, soil contamination) and global warming or climate change.[citation
needed]
Habitat size and numbers of species are systematically related. Physically larger species and
those living at lower latitudes or in forests or oceans are more sensitive to reduction in habitat
area.[84] Conversion to "trivial" standardized ecosystems (e.g., monoculture following
deforestation) effectively destroys habitat for the more diverse species that preceded the
conversion. In some countries lack of property rights or lax law/regulatory enforcement
necessarily leads to biodiversity loss (degradation costs having to be supported by the
community).[citation needed]
A 2007 study conducted by the National Science Foundation found that biodiversity and genetic
diversity are codependent—that diversity among species requires diversity within a species, and
vice versa. "If any one type is removed from the system, the cycle can break down, and the
community becomes dominated by a single species."[85] At present, the most threatened
ecosystems are found in fresh water, according to the Millennium Ecosystem Assessment 2005,
which was confirmed by the "Freshwater Animal Diversity Assessment", organised by the
biodiversity platform, and the French Institut de recherche pour le développement (MNHNP).[86]
Co-extinctions are a form of habitat destruction. Co-extinction occurs when the extinction or
decline in one accompanies the other, such as in plants and beetles.[87]
] Introduced and invasive species
Male Lophura nycthemera (Silver Pheasant), a native of East Asia that has been introduced into parts of
Europe for ornamental reasons
Barriers such as large rivers, seas, oceans, mountains and deserts encourage diversity by enabling
independent evolution on either side of the barrier. Invasive species occur when those barriers
are blurred. Without barriers such species occupy new niches, substantially reducing diversity.
Repeatedly humans have helped these species circumvent these barriers, introducing them for
food and other purposes. This has occurred on a time scale much shorter than the eons that
historically have been required for a species to extend its range.
Not all introduced species are invasive, nor all invasive species deliberately introduced. In cases
such as the zebra mussel, invasion of US waterways was unintentional. In other cases, such as
mongooses in Hawaii, the introduction is deliberate but ineffective (nocturnal rats were not
vulnerable to the diurnal mongoose). In other cases, such as oil palms in Indonesia and Malaysia,
the introduction produces substantial economic benefits, but the benefits are accompanied by
costly unintended consequences.
Finally, an introduced species may unintentionally injure a species that depends on the species it
replaces. In Belgium, Prunus spinosa from Eastern Europe leafs much sooner than its West
European counterparts, disrupting the feeding habits of the Thecla betulae butterfly (which feeds
on the leaves). Introducing new species often leaves endemic and other local species unable to
compete with the exotic species and unable to survive. The exotic organisms may be predators,
parasites, or may simply outcompete indigenous species for nutrients, water and light.
At present, several countries have already imported so many exotic species, particularly
agricultural and ornamental plants, that the own indigenous fauna/flora may be outnumbered.
] Genetic pollution
Endemic species can be threatened with extinction[88] through the process of genetic pollution,
i.e. uncontrolled hybridization, introgression and genetic swamping. Genetic pollution leads to
homogenization or replacement of local genomes as a result of either a numerical and/or fitness
advantage of an introduced species.[89] Hybridization and introgression are side-effects of
introduction and invasion. These phenomena can be especially detrimental to rare species that
come into contact with more abundant ones. The abundant species can interbreed with the rare
species, swamping its gene pool. This problem is not always apparent from morphological
(outward appearance) observations alone. Some degree of gene flowis normal adaptation, and
not all gene and genotype constellations can be preserved. However, hybridization with or
without introgression may, nevertheless, threaten a rare species' existence.[90][91]
] Overexploitation
Overexploitation occurs when a resource is consumed at an unsustainable rate. This occurs on
land in the form of overhunting, excessive logging, poor soil conservation in agriculture and the
illegal wildlife trade. Joe Walston, director of the Wildlife Conservation Society’s Asian
programs, called the latter the "single largest threat" to biodiversity in Asia.[92] The international
trade of endangered species is second in size only to drug trafficking.[93]
About 25% of world fisheries are now overfished to the point where their current biomass is less
than the level that maximizes their sustainable yield.[94]
The overkill hypothesis explains why earlier megafaunal extinctions occurred within a relatively
short period of time. This can be connected with human migration.[95]
] Hybridization, genetic pollution/erosion and food security
The Yecoro wheat (right) cultivar is sensitive to salinity, plants resulting from a hybrid cross with cultivar
W4910 (left) show greater tolerance to high salinity
: Food Security and Genetic erosion
In agriculture and animal husbandry, the Green Revolution popularized the use of conventional
hybridization to increase yield. Often hybridized breeds originated in developed countries and
were further hybridized with local varieties in the developing world to create high yield strains
resistant to local climate and diseases. Local governments and industry have been pushing
hybridization. Formerly huge gene pools of various wild and indigenous breeds have collapsed
causing widespread genetic erosion and genetic pollution. This has resulted in loss of genetic
diversity and biodiversity as a whole.[96]
(GM organisms) have genetic material altered by genetic engineering procedures such as
recombinant DNA technology. GM crops have become a common source for genetic pollution,
not only of wild varieties but also of domesticated varieties derived from classical
hybridization.[97][98][99][100][101]
Genetic erosion coupled with genetic pollution may be destroying unique genotypes, thereby
creating a hidden crisis which could result in a severe threat to our food security. Diverse genetic
material could cease to exist which would impact our ability to further hybridize food crops and
livestock against more resistant diseases and climatic changes.[96]
Climate Change
Main article: Effect of Climate Change on Plant Biodiversity
Polar bears on the sea ice of the Arctic Ocean, near the North Pole. Climate change has started affecting
bear populations.
Global warming is also considered to be a major threat to global biodiversity.[citation needed] For
example coral reefs -which are biodiversity hotspots- will be lost in 20 to 40 years if global
warming continues at the current trend.[102]
In 2004, an international collaborative study on four continents estimated that 10 percent of
species would become extinct by 2050 because of global warming. "We need to limit climate
change or we wind up with a lot of species in trouble, possibly extinct," said Dr. Lee Hannah, a
co-author of the paper and chief climate change biologist at the Center for Applied Biodiversity
Science at Conservation International.[103]
RED DATA BOOK
A Red Data Book contains lists of species whose continued existence
isthreatened. Species are classified into different categories of perceived
risk. Each Red Data Book usually deals with a specific group of animals or
plants (e. reptiles, insects, mosses). They are now being published in
many different countries and provide useful information on the threat
status of the species.
The red-listing assessment is a simple logical process to determine the
status of threat to a species based on available information. In 2004 a
training workshop was conducted in Lao PDR on redlisting assessment
methodologies.
The MWBP red-listing process will be conducted on selected species groups
in addition to the flagship species. Of the four Flagship Species of the
MWBP, three have been categorized as Critically Endangered (Cr).
One of the key outputs of this process is production of a Regional Red Data
Book for the Lower Mekong Basin in five languages.
The process:
• Determine through a consultative process which groups of wetland
species to carry out red listing process
• Carry out initial red-listing process for flagship and associated species,
as part of action planning process
• Organise a training workshop on the Red-listing process
• National expert groups trained government counterparts collect
information on species selected, and carry out process at national level
• Regional expert groups meet to collate the data and go through red
listing process
• Send results to Species Survival Commission for ratification
In-situ and Ex-situ Conservation Methods
In Situ Conservation Methods
In-situ conservation, the conservation of species in their natural habitats, is considered the
most appropriate way of conserving biodiversity.
Conserving the areas where populations of species exist naturally is an underlying condition
for the conservation of biodiversity. That's why protected areas form a central element of
any national strategy to conserve biodiversity.
Ex Situ Conservation Methods
Ex-situ conservation is the preservation of components of biological diversity outside their
natural habitats. This involves conservation of genetic resources, as well as wild and
cultivated or species, and draws on a diverse body of techniques and facilities. Some of
these include:

Gene banks, e.g. seed banks, sperm and ova banks, field banks;

In vitro plant tissue and microbial culture collections;

Captive breeding of animals and artificial propagation of plants, with possible
reintroduction into the wild; and

Collecting living organisms for zoos, aquaria, and botanic gardens for research and
public awareness.
Ex-situ conservation measures can be complementary to in-situ methods as they provide
an "insurance policy" against extinction. These measures also have a valuable role to play in
recovery programmes for endangered species. The Kew Seed Bank in England has 1.5 per
cent of the world's flora - about 4,000 species - on deposit.
In agriculture, ex-situ conservation measures maintain domesticated plants which cannot
survive in nature unaided.
Ex-situ conservation provides excellent research opportunities on the components of
biological diversity. Some of these institutions also play a central role in public education
and awareness raising by bringing members of the public into contact with plants and
animals they may not normally come in contact with. It is estimated that worldwide, over
600 million people visit zoos every year.
Ex situ conservation measures should support in-situ conservation measures (in-situ
conservation should be the primary objective).
Biogeographic zones of India
This map shows biogeographic zones and biogeographic provinces of India as
revised by Rodgers, Panwar and Mathur (2002).
Description
Biogeographic classification of India was done by Rodgers and Panwar (1988),
describing 10 biogeographic zones in India, further divided into 25
biogeographic provinces. The maps were further revised by Rodgers, Panwar and
Mathur (2002), using GIS techniques into 10 zones and 26 provinces. The
classification was done using various factors such as altitude, moisture,
topography, rainfall, etc. Biogeographic zones were used as a basis for
planning wildlife protected areas in India.
Methods
The GIS data was created from a revised biogeographic map of India by Rodgers,
Panwar and Mathur (2002). The map also has codes for the zones and the
provinces, along with the area (in sq. km) information.