Human Activities and Their Impacts on Biodiversity

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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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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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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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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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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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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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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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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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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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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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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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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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

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Human Activities and Their Impacts on Biodiversity