Threats to biodiversity Chapter 2
Any process or event whether natural or human-induced that is likely to cause adverse effects upon the status or sustainable use of any component of biodiversity is referred to as a threat.
Habitat threat
it is the natural place where plants, animals, or other organisms live; it is what they call home. For example, terrestrial vegetation types may be forest, desert grassland, and freshwater habitat including streams, rivers, and lakes. while marine habitats include salt marshes,open seas, and deep water.
Habitat Alteration
it is change in land use or land cover that has impact on local ecosystem .
1- it may lead to habitat loss that is greatest current threat to living organisms.
2- large area of water and land is damaged by human activities such as over fishing and urbanization
3- Destruction of habitat results in loss of species.
Types of habitat destruction
1-Fragmentation
2-Degradation
Habitat Fragmentation
when habitat is broken into pieces or fargments called habitat fragmentation
For example a road cut the area of habiat half and cause lack of resources of species.
Habitat degradation
the process in which beauty and quality of habitat us destroyed is called habitat degradation.
For example:-
absence of fish and water
loss of beauty from environment
Causes of degradation
1- deforestation
2- un planned constructio
3- chemical influence
4- defective agricultural policies
5 secondar pollutants
6- over use of vehicles
Effects of degradation
1- Depletion of natural resources
2-wildlife extinction
3- formation of acid rain
4- destruction of biodiversity.
5- pollution
6- Reduction in natural quality of water system
Species altering the habitat
Pathogens:-
A chestnut blight , a fungus that kill the chestnut trees.it result in destruction of moths due to chestnut trees destruction.
Predation
Brown trees snakes were introduced to pacific ocean which wiped out 3/4 of native birds and lizard species
competition of resources
zebra mussels are an invesive species.it can complete with native species for food and space . Invasive species hold space and food of native mussels species
Overharvesting :-
This results when individuals of a particar are taken at higher rate than can be sustained by the natural reproductive capacity of the population being harvested.continuous overexploitation can lead tu destruction of tge resources that term applies to natural resources such as wild medicinal plants grazing postures ,game animals forest etc.
More population___ more requirements __ utilization of resources __degradation of ecosystem ___ eliminating of species
Effects of over harvesting
it leads to resource destruction including extinction of species
it directly impact on humans
For example by decreasing biodiversity that necessary for medical resources ,human can suffer from many diseases.
it also disturb the balance of ecosystem and is very dangerous for survival of species.
for further economic growth .Historical utilization of forest products including timber and fuel wood have important role in humans societies.
A man is cutting forest for necessaties of life .In this way damag countless species of forest habitat.
in developing countries like pakistan almost three billion people reply upon wood for haeting and cooking
According to FAQ 10% forest area must be present in each country but pakistan has 2.2% forest area .the ideal forest area in a country is 25 %.
Effects of deforestation
Due to deforestation temperature is increasing every year.Due to increase in temperature galciers melt and sea level increase and it cause flooding. Due to this ,raining cycle per year is also disturbing that affected on life cycle of insects .For example butterflies represent the clean and clear environment .
Excessive use of water:-
water is natural renewable resource but today it is being used in excessive amount that cycle of balancing water is not maintained. By this, many plant species have died due to lack of water .
Overfishing
Fishing is major food of peoples of Pakistan,living near oceans and seas. They are using excess fishing than their requirements .Mostly overfishing occurs in karachi .
Endaangered species in Pakistan:-
1- markhor
2- Black finless porpoise
3- Asian black bear
4- indus river ,Dolphin
5- Mountain weasel
6- European Otter
7- snow leopard
8- Baluchistan Forest Dormouse
Causes of over exploitation
Rapid increase in population and change in lifestyle
Lack of alternate mean of energy especially for rular household
Weak capacities of the public sector agencies and the local communities to manage their forest sustainability
Lack of advanced machinery to manage an regenerate the forest
Lack of recognition of environment resources including recycling of water biodiversity conservation, carbon fixing and control of soil erosion
Recommendations
A strict policy should be formed addressing the overharvesting in pakistan
People should strictly follow the environment laws
There should be a proper check and balance systematic regarding the maintenance of environment
People must be awar of overharvesting
There should other alternative resources sp that the natural resources take time to compensate the loss
Deforestation
The set of clearing the wide area off the tress or the permanent destruction of forest in order to make the land available for other uses is called deforestation.
Types
There are three major types of Deforestation.
(a) selective cutting
(b) clear cutting
(c) slash and burn
Selective cutting
It is the cutting down of the selected tree in a forest so that the growth of other tree is not affected.
Clear cutting
It is a practice in which most or the trees in an area are uniformly cut down.
Slash and Burn
The existing vegetation is cut down and burned off before new seeds are sown.
Causes of Deforestation
1.increasing population demands more land for building houses,industries,roads,market etc.
2.Deforstation is done to clear the forest so that land can be used for grazing of cattle.
3.Need for agriculture land also causes deforestation.
4.forest are cut down to obtain fuel,wood and for making wood products.
According to United Nation Framework Convenience on climate change (UNFCCC) secretrait describe causes of deforestation as
1) Subsistence farming os responsible about 48%.
2) Commercial agriculture is responsible about 32%.
3) Logging is responsible about 14%.
4) Fuel wood removal about 5%.
Environmental problems due to deforestation:
Atmospheric and hydrological are two important problems.
1) Atmospheric:
Tropical deforestation is responsible for 20% of world green house gas emissions. CO2 gas emissions from deforestation contributes about 12% anthropogenic CO2 emissions with range from 6 to 17%. After deforestation about 1.5 billion tons carbon increased in atmosphere every year.
2) Hydrological:
Deforestation also exerts an effect on water cycle.Trees extract ground water through roots and release into atmosphere by transpiration. Deforestation causes atmosphere and soil dryness. It reduces soil cohesion, so that erosion, flooding and landsliding ensue. Low precipitation, localized floods are also results of deforestation.
Effects of deforestation:
I)Soil erosion is caused by deforestation because the root of trees hold the soil for particals and soil layers
Ii) CO2 level is increased in the atmosphere due to deforestation because trees are not available to removed excess CO2 from the air
III) increased CO2 leads to green house effect and global warming
Iv) climate change are drastic leading malting of glaciers increased foods,storms erc
V)60-90 of all terrestrial species are found in forest deforestation also lead to loss of natural habit which leads to loss of biodiversity
Iv) desertification
Vii) we are losing 173 species of plant and insects every year
World wide rate of deforestation:
Brazil has started deforestation sinces 1970. 700,000 square kilometer of Amazon rain forest has been deforest 39,194 fire were observed in Amazon since January 2019 leading to destruction of habit are thousands species it hosts 50, 20% of the world biological diversity and a average of new animal species descovred each ear
USA has cased destruction of forests 75% since 1600
In Africa UpTo 5800 squaras miles are lost every year due to deforestation it causes threats to African biodiversity it causes 20-30% decline in lack productivity
Deforestation in Pakistan
Pakistan has highest deforestation rate in Asia and about 0.2-2.5% anually at the time of independence Thier was 33% of forest about no only 2.2 % ate remaining and 61000
Hectors of forest land has been converted to forest land if it continues to present rate Pakistan will run out of forest after 50 year
In Punjab 99711 acres of forest are removed and in Sindh 27874 acres of forests are removed
Effect on Pakistan is biodiversity:
Millions of speech list losing their habit due to deforestation some examples are i)chirr pheasants ii) Musk beer
III)Balochistan black bear iv)finlist propoise
v) Markhor 2500 individuals are left in Pakistan ,and the main cases is the destruction of their habit forest
Step of controlling deforestation:
a) Individuals levels:
I) plant a tree
Ii) useless paper
III) paper and card board
I) use recycled products
V) by only sustainable wood products
Iv) do not by products countining plane oil
b)Government levels
I) billion trees tsunamis project were started in June 2015. Their missions was to plant spalinngs by the end of 2017
Ii) national forest policy 2015.
III) climate change monistry has initiated a project add the the cost of rupees 3.652 billion in all the Pakistan it's mission is to plant 100 million new trees and untill 2021.
Iv) revival a forestry resources in Pakistan is initiated under the prime ministers green Pakistan program
V) reducing emissions from deforestation and forest degrajuation is new mechanism in which that will protect protect develop forest will be rewarded by cash compensation
Climate change
Climate change is the long term change in the weather patterns in a region
Climate:
Climate is the weather of a place avereged over a period of time often 30 year
Weather
Weather is the to day state of atmosphere and it's show time variation in minutes
Causes of climate change:
Increase in CO2 concentration is the major cases of climate change Wich is called global warming
Along CO2 in other green house gases methanc also causing causing climate change natural causing human activities both emite green house gases nitrous oxide hydrosulpric carbons methane etc
Climate change in the world ,
Human activities
It includes;
1) Burning of fossil fuels
2) Agriculture
3) changes in land use pattern
1)*Burning of fossil fuels
Burning of fossil fuels like coal and oil has increased the concentration of CO2 in the atmosphere.The contribution of fossil fuels in green house gases is 70 to 80% over last 55 years the CO2 emissions from fossil fuels use and forest destruction has increased dramatically atmospheric CO2.
2)*agriculture
Green House gas emission from agriculture come from livestock such as cow, agricultural soil and rice production and its contribution in emission of gas is 10 to 15%.
3)*change in land use pattern
Clearing of forest for cultivation, industry and other human activities have increased concentration of gases and its contribution is 5 to 10% .The industrial activities that our modern civilization depends upon have raised atmosphere CO2 level from 280 part's per million to 400 parts per million in last 150 years.
.*Natural Causes
The climate change can also be caused by natural factors such as volcanic activity and solar radiations.It includes;
i)*Volcanic eruptions:
Volcanic eruptions are responsible for releasing molten rock or lava from deep within the earth.The gases and dust particles thrown into the atmosphere during volcanic eruptions have influence on climate.most of particles spread from Volcanic eruptions cool the planet by shading incoming solar radiation.
ii)*Solar radiations;
Nuclear fusion deep within the sun releasing a tremendous amount of energy that is slowly transferred to solar surface, from which it is radiated into apace.
Sun is mostly responsible for less than 15% of global temperature increases.
.*effect of climate change
The increase in temperature is causing warming of oceans, melting of ice and increased in evaporation.The effect have several physical impact on biodiversity.
Glaciers are also retreating almost everywhere in the world including Himalayas,Africa etc.
.*Sea level rises
Sea level rise if primarily caused by water from melting ice sheets and glaciers as it warms . The rise in sea level had adverse impact on population living in coastal areas and also play a role in flooding and increased in stroms .sea level is increasing 1-2 mm per year over the last century.
Changing climate leads to changes in frequency , intensity , duration and timing of weather some of the changes in weather pattern include an increase in the number of warm days and nights and decrease in cold days and night and an increase such as sea level rise and visibility in weather pattern the impect of these physical changes is now becoming visible on biological and human system and also have harmful impacts on marine ecosystem.
Ocean warming
The ocean absorb almost 90% of the excess heat from the surrounding air making it wear the rate of warming is increasing as heat is reaching deeper water
Changes in snow ice and froze ground
Increase in the temperature directly impacts on snow ,river and lake ice ,sea etc Glacier, ice caps are frozen ground . Rise in temperature cause decline in ice mass.Measurement NASA's satellite shows that the Antarctics and green land mass is declining at unprecedent rate in the frequency and intensity of daily temperature extremes some of extreme weather event include floods droughts and heat waves
How is Pakistan affected by climate change?
1) Glaciers melt in Himalayas is projected to increase flooding will affect water resource with in next two or three decades
2)freash water available is also projected to decrease which will lead to increased flooding from the seaand in some cases the river
3) coastal areas in south Pakistan will be at great risk due to increased flooding from the sea and in some cases the river
4) Being a predominantly agricultural economy , climate change is estimated to decrease in crop yield in Pakistan which in turn will affect livelihood and food production
Solution for climate change
1) move closer to work
Temperature is the second leading source of greenhouse gas emission.Burning a single gallon of gasoline produce 20 pound of CO2 so it's to move closer to work, use public transports than own car, walking cycling etc
2) stop cutting down trees
Evey year 33 million acres of forest are cut down .This is controlled by forest management balancing the amount of wood taken out with the amount of new tress growing
3) Unplug
: Today, we spend more money on electricity by turning on all the power devices when we are not at home ate not in use
: Evey efficient gadget can also save both and money and thus prevent more green house gas emissions
: Replacing old light bulb with compact fluorescent would save billions of KWh.
In America, replacing just one light bulb in every American home would save enough energy to provide energy to 3 million American homes.
Pollution :
The introduction of harmful particles into environment which causes the Harniful or poisonons effect to our environment is called pollution.
These harmful particles which cause poisonous effects are called pollutants. Nowadays pollution has reached its peak that causes adverse change and human illness,
Primary pollutants:
The pollutants that are released directly from the source i.e. CO, SO, ete, - Secondary pollutants:
The pollutants that are released indirectly from the source. When primary pollutants react in atmosphere with other substances to form secondary pollutants i.e,
ozone, nitrogen dioxide, acid rain etc. . Types of pollution
Following are the major five types of pollution.
i. Air pollution
ii. Soil pollution
iii. Water pollution
iv. Noise pollution
v. Radioactive pollution
Air pollution
When pollutants are present in air, this is called air pollution. It is the most dangerous form of pollution for life.
Types of air pollutants:
; a) Sulphur dioxide
Sources Burning of fossil fuels such as coal oil and gas release sulphur dioxide and nitrogen , oxides in the atmosphere.
Effects
i) Damages plants and animals.
ii) So2 penetrates into leaves through stomata causing damage to leaves and kills the plants.
iii) In North America, from smelting work, SO2 releases that completely destroy the . vegetation.
iv) In human, it damage lining of eyes, air passage and lungs.
v) Prolong exposure to SO2 causes respiratory diseases.
b) Lead Sources
Lead may be present in air, water and food. Some fossils fuels such ae petrol also release Pb on burning. It is used as anti-knocking agent. Paints, toys, cosmetics and folk ,medicines are sources of lead. It is also produced by fission of radioactive substances
Effects
Anemia, cramp, loss of muscles control, coma, kidney and brain damage i human, death and forest decline are some effects of lead comprunde '
¢) Carbon dioxide Sources
i) Burning of organic compounds in industries and automobiles
ii) Respiration process.
Effects
i) Causes greenhouse effect.
ii) Causes global warming.
iii) Causes in melting of ice.
iv) Rises sea level water and causes flooding.
d) Carbon monoxide
Sources
Incomplete burning of carbonates and carbon compounds release carbon monoxsde
Effects
i) It combines with hemoglobin to form carboxy hemoglobin. It reduces the blood ‘capacity to transport oxygen. It also damages brain and causes headaches and death.
e) Chlorofluorocarbons Sources
Aerosol spray, foam packing, air conditioning system and refrigerators. Effects
i) Breakdown of ozone layer
ii) Allows ultraviolet radiation to penetrate to earth
iii) ‘Increasing risk of cancer
iv) Cataracts in humans
v) Distorts weather pattern
Vi) Destroys plants, animals and planktons.
Smog
Smog is a mixture of smoke and fog. Atmospheric pollutants when reacting with Water Vapours then smog is formed. Effects
Causes irritation of the eyes, nose, and throat.
ii) Long exposure causes lung cancer.
iii) In London in 1952 it causes 400 deaths only in 5 days
Air pollution is mainly caused by
© Direct release of smoke from combustion,
Industrial activities
Vehicles combustion of fossil fuels Combustion of agricultural wastes Electronic devices for example refrigerators, room heaters, etc.
Volcanic eruption
Biological ammonification
Effects
Air pollution causes
Asthma, respiratory diseases, lung cancer, etc.
Air pollution is the major cause of global warming, greenhouse effect and acid rain. Ways to reduce air pollution:
i) Use of catalytic convertor in cars.
ii) Less use of vehicles
iii) Use of filters or scrubbers on the chimneys
iv) Use of non-fossil fuel factories
v) Use of alkali to neutralize acidic waste products
vi) Use of ozone friendly products.
Types of air pollution:
1) Acid rain
Sulfur dioxide and nitrogen oxide react with oxygen and rainwater to form sulphuric acid and nitric acid respectively. Rain containing these acids is called acid rain. . Effects:.
i) Acid rain decreases pH of water of rivers and lakes and so damages living organisms.
ii) Kills decomposers and microorganisms. iii) It deprived the soil from valuable nutrients such as calcium and potassium, and plants become vulnerable to infections.
iv) Plants become poisoned.
v) It corrodes the materials such as metals and stones.
Causes:
1) Natural events such as volcanic activity add a large amount of sulphuric acid.
2) Industrial activities and automobiles release oxide of nitrogen and sulfur.
3) Motor vehicles are the major source of nitrogen oxide.
4) In electrical power plants, sulfur dioxide and nitrogen oxide are released by the burning of fossil fuels.
5) The main cause of acid rain is construction of smokestacks which release sulphur rich smoke.
2) Ozone layer depletion
In stratosphere about 10-50 km. above earth ozone layer is present that filters UV radiations. Ozone layer is rapidly depleting by increasing level of CFCs which contains . chlorine, fluorine and carbon. CFCs are produced by cooling systems. Chlorine single atom can react with UV rays and destroy one million ozone molecules. As ozone becomes thinner, more UV rays from sun are able to reach on earth. Ozone layer over _ Antarctica and arctic regions has fallen drastically and has led to a hole. Effects of UV
i) Increase global warming.
ii) Cause skin cancer.
iii) Cataracts in-human.
iv) Distort.weather pattern,
v) Affect crops, plants and marine planktons.
3) Greenhouse effect
Light rays from the sun penetrate the glass of green house and are absorbed by the plants’ and soil and then reradiate as longer wave infra red radiations (heat). The glass does not permit theses rays to escape outside and so the heat remains within the green house. This increase in temperature is called greenhouse effect. The carbon dioxide in the atmosphere acts as glass of green house. It absorbs the reradiated rays from the plants and soil and does not allow escaping outside; as a result temperature of atmosphere is increased.
Causes of greenhouse effect:
Over urbanization, deforestation and industrialization.
Effects:
Global warming, rapid ice melting, floods and change in global weather pattern.
vii) Water pollution Water is an important part of our life. We are all dependent on water directly or indirectly. When pollutants materials are present in water then this type of pollution is refer as water pollution.
Causes
Water pollution is caused by dumping industrial wastes directly into rivers, ponds, seas, etc.
Human daily activities like washing clothes near ponds, lakes, and rivers also cause water pollution
Fertilizers contain nitrates and phosphates that cause eutrophication.
Pesticides.
Effects
Drinking polluted water causes cholera, diarrhea, hepatitis, etc.
It also affects aquatic life and indirectly human who depends on them.
Anaerobic bacteria break the organic compounds of sewage and release foul smells due to hydrogen sulfide and ammonia.
Mercury present in industrial wastes causes polaoning and resulta will be blindness paralysis and death.
Higher biological oxygen demand (BOD) indicates higher degree of pollution and imbalance in aquatic ecosystem.
Some pesticides such as DDT (dichloro-dipheny! trichlorocthane) are non degradable and cause mutations.
viii) Soil / Land pollution
Soil pollution is caused by introduction of harmful chemicals in the soil due to human activities like using pesticides (insecticides, herbicides and fungicides) thal absorb nitrogen compounds from the soil and make soil polluted.
Causes
Industrial and commercial waste Industrial and commercial wastes Deforestation
Combustion of agricultural wastes also causes soil pollution
Effects
Soil erosion ( soil loses its quality plants cannot grow properly and cannot hold the soil)
Soil pollution effect on farm output ratio and it also contaminated the ground water
ix) Noise pollution
Pollution caused by sound is called noise pollution.
Causes
Sound produced by the vehicles and industries
Harmful effects
- Hearing loss
- Sleep disturbance
- Hypertension
- Mental losses
- Tension
x) Radioactive pollution
Pollution caused by radioactive materials is called radioactive pollution.
Causes
- Nuclear plants
- Nuclear waste disposal
- Harmful effects
- Skin and blood cancer
- Infertility of soil
- Birth defects
- Blindness
- Excessive heat release in the environment increases the earth's temperature and causes drastic climate change.
- Effects of pollution
- Environment degradation
- Human health problems
- Global warming
- Depletion of the ozone layer
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