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7/31/2019 Human Activities and Their Impacts on Biodiversity
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Human activities Human activities and
their impacts on biodiversity and theirimpacts on biodiversity
HUMAN ACTIVITIES ANDTHEIR IMPACTS ON
BIODIVERSITY
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Contents of Presentation
Human activities An Introduction
1. Habitat destruction
2. Human population growth3. Pollution
4. Agriculture
5. Poaching/hunting6. Climate change
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Habitat destruction
Definition:
Habitat destruction is the process by which naturalhabitat is damaged or destroyed to such an extent thatit no longer is capable of supporting the species and
ecological communities that naturally occur there. Itoften results in the extinction of species and, as aresult, the loss of biodiversity.
Habitat can be destroyed directly by many humanactivities, most of which involve the clearing of land forother uses such as agriculture, mining, logging,hydroelectric dams and urbanization.
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Habitat destruction
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Human population growth
The geometric rise in human population levelsduring the twentieth century is the
fundamental cause of the loss of biodiversity.It exacerbates every other factor having animpact on rainforests . It has led to anunceasing search for more arable land forfood production and livestock grazing, and forwood for fuel, construction, and energy.
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Conti.
The human population was approximately
600,000 million in 1700, and one billion in
1800. Just now it exceeds seven billion, and
low estimates are that it may reach 10 billion
by the mid-21st century and 12 billion by
2100.
Pakistan approximately 18crore
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Pollution
Pollution: Industrial, agricultural and waste-
based pollutants can have catastrophic effects
on many species. Those species which are
more tolerant of pollution will survive; those
requiring pristine environments (water, air,
food) will not. Thus, pollution can act as a
selective agent.
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Water pollution
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Conti..
Pollution of water in lakes and rivers has
degraded waters so that many freshwater
ecosystems are dying. Since almost 12% of
animals species live in these ecosystems, and
most others depend on them to some degree,
this is a very serious matter. In developing
countries approximately 90% of wastewater isdischarged, untreated, directly into
waterways.
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Agriculture
The dramatic increase in the number of humansduring the twentieth century has instigated aconcomitant growth in agriculture , and has led to
conversion of wild lands to croplands, massivediversions of water from lakes, rivers and undergroundaquifers, and, at the same time, has polluted water andland resources with pesticides, fertilizers, and animalwastes. The result has been the destruction,
disturbance or disabling of terrestrial ecosystems, andpolluted, oxygen-depleted and atrophied waterresources.
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Conti.
The native plants and animals adapted to the
local conditions are now being replaced with
foreign (or exotic) species which require
special inputs of food and nutrients, large
quantities of water. Such exotic species
frequently drive out native species. There is
pressure to conform to crop selection andagricultural techniques all is driven by global
markets and technologies.
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Conti..
Such exotic species frequently drive out native
species. There is pressure to conform to crop
selection and agricultural techniques all is
driven by global markets and technologies.
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Agricultural in swat pakistan
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Agricultural activity in swat pak..
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Climate change
Plants and animals are sensitive to fluctuations intemperature and climate. In the past, climate has variedconsiderably within short time scales. Evidence from fossilsand paleobiological studies have indicated that theseperiods of rapid climate change have been associated with
mass extinction events.
Almost all scientists are in agreement about one thing:human activities are exacerbating climatic conditions andspeeding up the rate of global warming. This is a directresult of the increase in production of greenhouse gases,such as CO2 (carbon dioxide) and CH4 (methane) due tothe burning of fossil fuels and incomplete combustion fromvehicles.
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Conti..
In addition, the release of anthropogenic
chemicals called CFCs - chlorofluorocarbons -
into the atmosphere has degraded the
stratospheric ozone layer around the Earth,which shields the planet from harmful
ultraviolet radiation. Changes in the integrity
of the ozone layer has resulted in increasedultraviolet radiation reaching the Earth's
surface.
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Climate change
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Poaching/hunting
Hunting, fishing, and gathering: Many forests
which appear intact are in fact empty
forests, since most large animals have been
hunted to unsustainable levels. These animalsare mainly hunted for meat.
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Conti
but also for skins (jaguar, ocelot) or
medicinal/chemical properties (poison-arrow
frogs, collected to provide poisons for arrow
tips, and the midwife toad, which in theAmazon is thought to have medicinal value).
Turtles are heavily harvested for meat and
their eggs are collected for food almosteverywhere in the tropics and subtropics..
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Poaching
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Conti..
Fish and aquatic animals are killed
indiscriminately by fishing techniques which
employ insecticides and/or dynamite. These
techniques not only catch the few desiredspecimens, but kill all of the other animals in
the area. Commercial fishing operations are
not sensitive to issues of sustainability..
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Conti
They catch as many marketable fish as
possible, and intensify their efforts when fish
populations drop (declines due in the first
place to overfishing). Such unsustainablefishing operations have led and are leading to
severe declines in fish in major river systems
within tropical rainforests
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Overharvesting/Overexploitation
Humans have historically exploited plant and animalspecies in order to maximize short-term profit, at the
expense of sustainability of the species or population.This exploitation follows a predictable pattern: initially,a species harvested from the wild can turn asubstantial profit, encouraging more people to getinvolved in its extraction. This increased competition
encourages the development of more large-scale andefficient methods of extraction, which inevitablydeplete the resource.
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Overharvesting/Overexploitation
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Introduction of exortic species
Plant and animal taxa in a particular area thathave been introduced by humans intentionally orunintentionally to areas outside their place oforigin & natural range of distribution are called
Exortic species .
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Exotic Specie
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Conti..,
Species introductions can occur accidentally,when organisms introduced into new systemson other animals or objects. For instance,
zebra mussels are thought to have beenbrought into the Great Lakes in the ballastwater of tankers that travelled up theLawrence Seaway.
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Conti
Unintentional species introductions can also
result from lack of education of the general
public. For instance, releasing aquarium fishes
or using exotic ornamental garden plantswhose seeds escape into natural systems can
increase the probability of an exotic species
becoming established in our nativeecosystems.
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conti
hybridization: Geographic barriers help tomaintain genetically diverse populations of
organisms. Introduction of non-native species,whether intentional or not, has resulted in theinterbreeding of native and non-native species,with the consequent decline of native species. It
has been estimated that hybridization was amajor factor in 38% of North American fishspecies extinctions.
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Conti..
disease and parasites: pest species
accidentally introduced to an area provide the
most dramatic example of the damage that
exotics can pose to native species. Forinstance, an exotic beetle was the vector for
Dutch Elm Disease, which has devastated elm
trees in North America.
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Conti..
homogenization of ecosystems: all the above
impacts combine to decrease the number of
native species in a habitat and replace them
with "weedy", widespread species - and thuscause regional homogenization of ecosystems.
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Thanks to All of You Dears