1. Introduction to biodiversity
The
variety of plant and animals life on earth, including genes, species and
ecosystems, is known as biological diversity. There are three major types of
biodiversity.
(i)
Habitat diversity (ecosystem diversity) – The variety of habitat types and
biologic richness of those habitats in an ecosystem.
(ii)
Genetic Diversity – The amount of variability that is available among the DNA
of individuals with in a population or species. Genetic variability gives
chances to species to compete, adapt, and survive.
(iii)
Species Diversity – The concepts of species richness and evenness. Species
richness refers to the number of species in a community. Species evenness is
the relative abundance of individual within each species.
2. The role of biological diversity
in living systems
Biological
diversity plays vital part in evolution of the new species. Evolution results
from genetic variability, mutation and natural selection. For example, when
individuals are force to adapt to a new environment whose characteristics allow
and adaptation successfully to the changes they will survive and produce
offspring with the same characteristics. The emergence of a new species by this
process or other mechanisms is called speciation.
A
number of circumstances lead to the isolation of a group of individuals. For
example, group of individuals could migrate across a river during a dry season
and later when the water is higher they might be cut off from their native
place or main population. This process is called divergent evolution.
Biodiversity
help to regulate the air, soil, and water purification and maintain their
quality. Cycling of nutrients provides essential minerals for living beings.
Examples are biogeochemical, nitrogen, sulphur and carbon cycles. Another
natural process of decomposition is help to regulate the environment through breaks
down the biodegradable matter into constituents. Biodiversity provides ecologic
benefits also. For example, wetland provides variety of environmental services
such as it’s a place for ground water storage and purifying toxins from soils
and water. Rain forests act as a carbon sequestration. In addition biodiversity
help for plant pollination. Insects, birds, bats and bees are important for
much plant pollination.
3. Threats to Biodiversity
3.1. Habitat loss and fragmentation
of biodiversity
Biodiversity
loss are caused by (i) habitat loss, fragmentation & degradation (ii) over
exploitation (iii) pollution (iv) introduction of invasive species and (v)
climate change
Habitat
loss connected with direct destruction of habitats. Complete loss of the
habitat means loss of the total occupying biodiversity in particular area.
There are three types of habitat loss was identified (i) destruction (ii)
fragmentation and (iii) degradation.
Fragmentation
means breaking up a habitat ecosystem into smaller fragments or patches which
have a smaller total area. Habitat fragmentation occurs when the size of
natural habitat area is reduced or when that area is cut off and isolated by
development activities. Fragmentation can damage the quality of habitat. For
example some species require habitat into the forest interior and they can’t
survive in the edge of forest or transitional zone because near the edge of
forest ecosystem characteristics are similar into adjacent areas. This is
called edge effect. New edge will occur when the forest area is clear by
development activities.
The
subject of habitat fragmentation comes from island bio-geography. The Theory of
Island Biogeography (Robert MacArthur and Edward Wilson) provides the
relationship between area and the number of species (or species richness) which
is described by the following equation.
| S=CAz |
S – Number of species in an island
A – Area of that island
C – Constant and will depend on both the taxon and
the bio-geographic province
z – Fitted constant (with 0.15-0.35)
An island is large and
it located near the land it’s a place for large habitat diversity and support
more species and greater chance to colonization and its give a path for low
extinction. If an island is small and far away from the mainland it support for
low species population and chance for low colonization and high extinction.
3.2.
Threats of extinction
In
earth history life was being shape up by through extinction within a short
geologically time. Several catastrophic episodes has influenced on species
modification and extinction of disappear. For example dinosaurs became extinct
65 million years ago by a giant meteorite impact. Generally extinctions are
caused by climatic change, volcanism or other catastrophic environmental
changes. But human activities are become as a dominant factor for today’s
extinction.
An
endangered species are the most vulnerable to extinction. Example includes the
black rhino, Siberian tiger, giant panda, mountain gorilla and many others. A
species show significant sign of decreases in population they will consider as
endangered species. Example is the gray wolf and sea otter. Some species are
more vulnerable and slow reproducers they will get more time to recovery from
natural catastrophe or human exploitation. Some are require unique types of
environment for their survival. Some species biologic and life style factors
has influence on their living habitat. For example Panda lives only in specific
places with certain conditions of environment.
Illegal
harvesting and over-exploitation of wild species for commercial allow to
greatest threats to biodiversity. Animals and birds are hunting for their
horns, feathers or any other various purposes. A rhinoceros or an elephant is
hunt for their horns. Many exotic fish, birds and plants are transported
illegally under poor conditions and they get die in that process.
Introduction
of exotic species is another major threat to biodiversity. Exotic species may
flourish in the new environment and become as an invasive species. They take
dominant place and wipe-out or force to migrated endemic species from their
native place.
4. Conservation of biodiversity
Conservation
biology is the applied science of maintaining the earth’s biological diversity.
Susan Jacobson (1990) describes his structure of conservation biology in
educational view.
Fig:
A Schematic view of the relationship between conservation biology and other
disciplines (Jacobson 1990)
Conservation
biodiversity requires mixture of approaches that include the concepts of
conservation. The basic principle of biodiversity conservation depends on
management of ecosystem. Managing ecosystem include protected area network,
managing cultivated and built ecosystems and restoring the degraded ecosystems.
There is important to ensure the habitat of species living without threatened.
Providing resources (water, physical environment, supplying foods, etc……),
control of predators, grazers, competitors and parasites which are cause
threats to endangered species.
Another
technique is development of the zoos, aquaria and botanical gardens which are conserve
the species through ex-situ conservation. The management of farms, forests,
grasslands and wetlands also include the framework of biodiversity
conservation.
Another
possible approach is tried to assign a value on ecosystem services – fresh water,
clean air, recreational benefits and so on. First step for this process has to
be valuing natural capital. Pavan Sukhdev, lead author of the 2010 The
Economics of Ecosystems & Biodiversity (TEEB) report is saying ‘you cannot
manage what you do not measure’. This is proposing with the value of changes of
ecosystem service flows. The safeguarding ways is ‘designing payments for
ecosystem services’ and going with the communities and land owners who need to
be pay considered to keep wetlands and forests intact. In Mexico deforestation
has been halved by 2003 law that allowed paying water charges by land owners
and willing to reduce the agricultural clearances.
In
other countries design ‘biodiversity credits’ that offer a rewarding to people that
those who willing to have desire to protect and manage biodiversity habitats. In
New South Wales, the state government department has setup a ‘Bio Banking’
scheme for developers and land owners those can trade biodiversity offsets.
Protecting
natural ecosystems can enhance the value for money in direct sense (E.g.
Protected areas….). But this approach is depending on effective way of
implementation. Force of law is the practical work to adapt these strategies.
The Convention on Biological Diversity, Convention on Climate change adapted a
strategic plan for the decade to 2020 is ‘Living in harmony with nature’. The plan
directs by governments and takes actions to restore biodiversity and ecosystem
services through protected areas, habitat restoration, species recovery programs
and other targeted conservation interventions’.
References:
1.
Barbara murck (2005); Environmental Science – A self-Teaching guide; John wiley
& sons; Inc; USA
2.
Mark Lynas (2012); The God species – How Humans Really can save the planet……;
Fourth Estate; London
3. http://www.algebralab.org/practice/practice.aspx?file=Reading_IslandBiogeography.xml
4. http://www.geolounge.com/island-biogeography/
