The world is losing species and biodiversity at an
unprecedented rate and its cause go deep ranging from a complex combination of
social, economic, political and biological factors. There is a biodiversity
crisis that has done irreparable harm to the countless species and the assaults
come from so many directions that nature can’t adjust.
E.O Wilson a
revolutionary biologist has coined the acronym HIPPO to describe these multiple
assaults: habitat destruction, invasive species, pollution, population increase
and over-grazing.
HABITAT DESTRUCTION
The word ‘Habitat’ means living space. This refers
to the process which habitat is unable to support the species present,
resulting in the species being displaced or destroyed and a reduced
biodiversity. Clearing habitats for agriculture is the primary reason of
habitat destruction. Mining, logging, trawling and urban sprawl as also some
other reason. . About 89% of bird species, 83% of mammals and 91% of plant
species have become extinct due to habitat destruction. As the climate changes,
the current habitats of innumerable plant and animal species will no longer be
suitable for them, because of changes in temperature, precipitation, storm
frequency etc.
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Impact of Habitat Destruction: When a
habitat is destroyed the plants, animals and any other species occupied in that
habitat are threatened since the habitat no longer has the capacity to sustain
the species.
INVASIVE SPECIES
This refers to when non-indigenous species compete
with the current species in a habitat for resources.
Invasive species refers to species, plants and
animals which are non-indigenous or non-native and have an adverse affect on
the habitat they invade. They disrupt by dominating the region. This term has
been uses by International Union for Conversation of Nature (IUCN).
Invasive species could also include when native
species disrupts the habitat by becoming dominant due to loss of natural
controls. (For example overpopulation a particular species). Common traits of
an invasive species are: the ability to reproduce both asexually and sexually,
fast growth, rapid reproduction, high dispersal rate, ability to adapt to suit
the conditions. These are also reason for its dominations in habitat areas. Lantana
in India is a common invasive species.
Examples – Nile Perch are large fish found in River
Nile which were introduced in Lake Victoria in Africa and thus were responsible
for the destruction of one entire habitat. Water hyacinth, water species from
Mexico, have choked water bodies in India and replaced natural vegetation.
Eucalyptus and Wattle have destroyed native forests in the mountains of the
Western Ghats in Tamil Nadu.
POLLUTION
Pollution comes in three forms: solid, liquid and
gaseous waste. Hence there are three types of pollution: air, water and soil
pollution. Pollution occurs when there is presence of substances beyond their
permissible limits in the atmosphere or water. It is the most subtle form of
habitat destruction, leading to loss of biodiversity and contamination or
disturbance of existing equilibrium. Pollution can also cause reduction and
elimination of sensitive species. Water pollution is caused by dumping organic
and human wastes, agricultural wastes and industrial effluents into the river
and ocean systems. Pesticides get mixed with the water and poison the fish.
Coral reefs are in danger by pollution and industrialization. Inorganic wastes
lead to Eutrophication or dying of water bodies. Air Pollution is one of the
major causes of Global Warming. Sulphur
Dioxide, Nitrogen Dioxide and suspended particles have an adverse effect on
plant and animal species. Pollution through biomagnifications can affect all
forms of life.
POPULATION
The population of the world is 6.2 billion and is
expected to rise to 9 billion by 2050. This raises the question whether there
will be enough resources to sustain the population. The large global population
of today, has put immense pressure on the habitat to sustain itself. Natural
resources are exploited at a destructive rate. There are water shortages, soil
exhaustion, loss of forest, air and water pollution. Most developed economies are consuming faster
than they can regenerate.
Protecting the environment and achieving better
standard of living go hand in hand. Slowing the increase of population will
reduce pressure on the environment, and gain time to improve standard of living
on a sustainable basis. Human Settlements and our expanding needs have turned
into encroachment on habitats of species. Most developed economies are
consuming faster than they can regenerate. There is a need for population
stabilization and resources conversation for the world to meet the challenges
of sustainable development.
OVER-HARVESTING
It is essentially about
sustainable use of renewable resources whether it is forests or fisheries.
Overharvesting pushes the ecosystem beyond repair. A large number of forest
lands are continuously cleared to convert it to grazing land for cattle. India
has a grazing land of only 13 million hectares and so more land is cleared. The
animals trample the seedlings and lead to a decrease in the water storing
capacity of the soil. Overgrazing destroys grasslands; plants become weak and
have reduced root strength. It leads to the inability of the forests to perform
their functions like acting as the catchment for rivers etc.
@Notes courtesy of Aparna, Shruti Gokhale, Dhanika and myself