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Threats to biodiversity Chapter 2

 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.



Threats to biodiversity Chapter 2


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

Causes of air pollution 

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

Pollution in Pakistan
According to a survey, 135000 deaths per year are attributed to ambient air pollution making it the leading cause of sickness and death in Pakistan.
Smog is public health emergency.
5.88% of GDP and $47.8 billion estimated economic burden in Pakistan. 
According to WHO (World Health Organization) report in 2014, 7 million people died worldwide due to air pollution

Pakistan ranked third worldwide among countries with the highest pollution-related deaths
Introduced species
or 
biological invasion
A species living outside its natural /native distributional range but which has arrived there by human activity either deliberately or accidentally is called introduced species

Invasive species
Introduced species that become established and spread beyond the place of introduction are ‘called invasive species. 
These species are also called alien species, exotic species, foreign species, non indigenous species or non-native species. 
Biological invasion 
A biological invasion consists of a species ‘acquiring a competitive advantage, following the disappearance of natural obstacles to its proliteration which allows it to spread rapidly and to conquer novel areas within recipicnt ecosystem tn which it become a dominant population. 
  An invasion species can be any kind of living organism i.e. amphibian, plants, insects, fish. fungus, bacteria or even an organism's seeds or eggs that is not native to an ecosystem and cause harm. 
Spread
The process of human caused introduction is distinguished from biological colonization in which Species spread to new areas through nature such as storms, rain splashes, small insects etc
. Example 
i. Spores that are a common means of reproduction in fungi may be spread by insects and by rain splashes.
 Categories ef invasive plants
Five categories of invasive plants such as 

Aliens
Plants whose presence in an area, beyond their known historical range is the result of human mediated transport (intentional or accidental).
ii-Casual Aliens 
Alien plants that flourish and reproduce occasionally outside the cultivation but do not farm selfreplacing population and eventually die out, they rely on repeated introductions for their persistence e.g. dlianthus altissia . 
iii)-Naturalized. Aliens that form self-replacing population for at least 10 years without direct intervention by people, they often recruit offspring freely and usually close to adult plants and do not necessarily invade the ecosystem.
e.g. Bougainvillea glabra 
iv. Invasive 
Plants are a subset of naturalized plants that produce reproductive offspring often in large numbers at considerable distances from parent plants and thus have the potential to spread over a p large area e.g. Datura stramonium
v. Transformer 
Transformer is a subset of invasive plants which change the character, condition, form or nature of ecosystem over a substantial area relative to extent of that ecosystem 
e.g. Eucalyptus citridora. 
Stages of invasion 
There are 4 stages of biological invasion
1) the First stage
involves movement of species from native to non native area. Various factors support this transfer i.e. human, other animals, wind, water etc.
2) the Second stage 
involves colonization of invasive species into new habitat. Successful” ; colonization favors’ to overcome natural resources and exploited successfully.
3) Third stage
involves establishment of invasive species into new habitat and production of new generation.
4) the Fourth stage
involves dispersal of new species and formation of new population across the environment. 
Effects 
The impact of introduced species is highly variable. Some introduce species may have negative , impact or minor impact while other have positive impact. Introduced species having positive impact have a lot of advantages for human being while species having negative impact have disadvantages for environment. 
Advantages 
i. Biological control
A control by living Organism is called biological control. In biological control pests are destroyed by using some living organisms that compete with or even eat them up.
For example an aphid that attacks walnut trees is being controlled biologically by a wasp that parasitizes this aphid. 
Pollution control 
Introduced species are effective pollution controllers without any destructionto , environment like transgenic bacteria have been introduced to control or prevent ; airborne chemical pollutants from being vented into air used as biofilter. They can also remove sulfur from coal before it is burned and help to clean up toxic waste dumps, these bacteria are given suicide genes that caused them to self destruction when the job had been accomplished. 
A weed called mouse-cared cress has been engineered to produce biodegradable plastic (Polyhydroxy butyrate) in cell granules.
iii. Treatment of diseases 
Transgenic bacteria are used for the production of insulin for the treatment of diabetes, hemophilia factor VIII, hepatitis B vaccine, etc. 
Gene therapy insertion of genetic material into human cells for the treatment of a disorder e.g, gene therapy is used in the treatment of severe combined immunodeficiency syndrome(SCID) which occurs mostly in those children that lack an enzyme adenosine deaminase ( ADA) that is involved in the maturation of T&B cells. Bone marrow stem cells are removed from the blood and infected with a retrovirus (RNA virus) that carries a normal gene for the enzyme then the cell is returned to the patient result an insufficient increase in their immune function which is associated with a sustained rise in the level of an ADA enzyme activity in the blood. 
>» Negative effects of invasive species
i. Increase in rate of soil erosion 
ii. Reduce soil values 
iii. Alteration of natural flora and fauna 
iv. Economic losses and risk of human health 
v. Modification of hydraulic cycle 
vi. Reduction in agricultural yield 
vii. Reduce water availabilities viii. Contribution to spread of vector-borne diseases.
Biodiversity in Pakistan and invasive flora 

6000 species of flowering plants representing 22 families and about 150 genera 
4 monotypic genera of flowering plants and around 400 species are endemic to Pakistan 
700 alien species of our vascular plants our deliberately introduced to Pakistan to get food, wood, and natural resources.
Methods used to control invasive species

i. Manual control
 This includes digging, Noodling, destruction, removal of nests, hand-pulling, burning, and genital destruction of invasive species by hand.
ii- Mechanical control 
Mowing, hosting, cutting, tilling, grinding, and constructing barriers to invasive species using tools or machines.
iii. Chemical control 
Includes pesticides besides fungicides and insecticides, The least labor-intensive operation, chemical control on its own is usually the most effective option because it. can target the specific species and will kill them
2.7. Desertification
What is Desertification?
Desertification is defined as a process of land degradation in arid, semi-arid, and subhumid areas due to various factors including climatic variations and human activities.
Desertification is a type of land degradation in which a relatively dry land region becomes increasingly arid, typically losing its bodies of water as well as vegetation and wildlife. 
Causes of Desertification:
1. Overgrazing 
Animal grazing is a huge problem for many areas that are starting to become desert biomes. If there are too many animals that are overgrazing in certain spots, it makes it difficult for the plants to grow back, which hurts the biome and makes it lose its former green glory.
2. Deforestation
When people need trees in order to make houses and do other tasks, then they are contributing to the problems related to desertification. Without the plants (especially the trees) around, the rest of the biome cannot thrive. 
3. Farming Practices 
Some farmers do not know how to use the land effectively. They may essentially strip the. land of everything that it has before moving on to another plot of land. By stripping the soil of its nutrients, desertification becomes more of a reality for the area that is being used for farming. 4. Excessive Use of Fertilizers and Pesticides 
The use of excessive amounts of fertilizers and pesticides to maximize crop yields in the short term often leads to significant damage to the soil. In the long run, this may tum from arable into arid land over time, and it will no longer be suitable for farming purposes after a few years of excessive farming since the soil has been damaged too much over time.
5. Over-drafting of groundwater
Groundwater is the freshwater found underground and is also one of the largest water sources. Over drafting is the process in which groundwater is extracted in excess of the. equilibrium yield of the aquifer that is pumping or the excessive pulling up of groundwater from underground aquifers. Its depletion causes desertification. 
6. Urbanization and Other Types of Land Development 
Land development can cause people to go through and kill plant life. 11 can also cause issues with the soil due to chemicals and other things that may harm the ground. As areas become more urbanized, there are fewer places for plants to grow, thus causing desertification.
7. Climate Change 
Climate change plays a huge role in desertification. As the days get warmer and periods of drought become more frequent, desertification becomes more and more eminent. Unless climate change is slowed down, huge areas of land will become desert; some of those areas may even become uninhabitable as time goes on. 
8. Stripping the Land of Resources 
If an area of land has natural! resources like natural gas, oil, or minerals, people will come and mine it or take it out. This usually strips the soil of nutrients, which in turn kills the plant life, and eventually leads to the process of becoming a desert biome as the line goes on.
9. Natural Disasters 
There are some cases where the land gets damaged because of natural disasters, including drought, In those cases, there isn’t a lot that people can do except work to try and help rehabilitate the land after it has already been damaged by nature. 
10. Soil Pollution 
Soil pollution is a significant cause of desertification. Most plants are quite sensitive to their natural living conditions. When soil becomes polluted due to various human activities, the respective area of land may suffer from desertification in the long run. Higher the level of pollution will be the degradation of soil over time. 
11 Overpopulation and excessive consumption 
Since our world population is continuously growing, the demand for food and material goods is also increasing at an alarming rate. Our overall level of consumption is also increasing at a steady rate. Thus to fulfill our demand, we have to optimize our farming processes to harvest even higher crop yields. However, this excessive optimization of farming will hurt the soil and will eventually turn into the desertification of land in the long run.
12. Mining 
Mining is another big reason for desertification. Large amounts of resources have to be extracted by industries to meet our demand for material goods. For mining, large areas of land have to be used, which causes deforestation as well as pollution of the nearby areas. By the time most of the natural resources have been extracted, and mining practices are no more profitable, the soil gets damaged significantly, the land becomes arid, which may not be recoverable, and desertification occurs. 

> Devastating Effects of Desertification
1. Farming becomes next to impossible 
If an area becomes a desert, then it’s almost impossible to grow substantial crops there without special technologies. This can cost a lot of money to try and do, so many farmers will have to sell their land and leave the desert areas.
2. Decrease in Crop Yields 
A major effect of desertification is the decrease in crop yields. Once land turns from arable to arid, it is often on longer suitable for farming purposes anymore. In tum, many farmers may lose their livelihood, since they often solely rely on farming as their single source of income. If their land becomes arid, they may no longer be able to provide sufficient crop yields to make a living out of it... 
3. Hunger 
Without farms in these areas, the food that those farms produce will become much scarcer, and the people who live in those local areas will be a lot more likely to try and deal with hunger problems. Animals will also go hungry, which will cause even more of a food shortage.
4-Flooding 
Without plant life in an area, flooding is a lot more imminent. Not all deserts are dry; those that are wet could experience a lot of flooding because there is nothing to stop the water from gathering and going all over the place. Flooding can also negatively affect the water supply, which we will discuss next. 
5. Poor Water Quality 
If an area becomes a desert, the water quality is going to become a lot worse than it would have been otherwise. This is because plant life plays a significant role in keeping the water clean and clear; without its presence, it becomes a lot more difficult for you to be able to do that.
6. Overpopulation 
When areas start to become deserts, animals, and people will go to other areas where they can actually thrive. This causes crowding and overpopulation, which will, in the long run, end up continuing the cycle of desertification that started this whole thing anyway. 
7. Poverty 
All of the issues that we've talked about above (related to the problem of desertification) can lead to poverty if it is not kept in check. Without food and water, it becomes harder for people to thrive, and they take a lot of time to try and get the things that they need. 
8. Biodiversity Loss 
In general, the destruction of habitats and desertification may also contribute to a loss of biodiversity. While some species may be able to adjust to the altered environmental conditions properly, many species will not be able to do so and may suffer from serious declines in population

9- Endangerment and Extinction of Species : 
The desertification results in a decline in population for which species may become. endangered or even extinct. This problem is especially severe for species that are already endangered as the small number of animals or plants that remains may also die off over time, which may even lead to the extinction of species. 
10. Destruction of Habitats
Desertification often leads to a loss of habitats for many animals and plants. ~ Desertification may alter the living conditions of the local flora and fauna making it impossible for animals and plants to sustain their populations. After desertification, regions suffer from water shortages due to climate change, and animals may suffer and die since water is vital for all life on our planet. 
11. Migration 
The desertification implies the destruction of the livelihood of farmers. This problem becomes. even worse when large areas of land that are currently used for farming will then no longer be suitable for farming due to a lack of water triggered by global warming. This results in serious Migration movements. 

Solutions to Desertification 

1- Policy Changes Related to How People can Farm 
In countries where policy change will actually be enforced on those in the country, policy change related to how often people can farm and how muck they can farm in certain areas could be put into place to help reduce the problems that are often associated with farming and desertification.  
2. Policy Changes to Other Types of Land Use 
If people are using land to get natural resources or they are developing it for people to live on, then the policies that govern them should be ones that will help the land to thrive instead of allowing them to harm the land further. The policy changes could be sweeping or they could be depending on the type of land use at hand. 
3. Education 
In developing countries, education is incredibly important too! that needs to be utilized in order to help people to understand the best way to use the land that they are farming on. By educating them on sustainable practices, more land will be saved from becoming desert. 
4. Technology Advances. 
Research is the key to overcoming most of our environmental problems, and it applies to desertification also. In some cases, it's difficult to try and prevent desertification from happening. In those cases, there needs to be research and application of the latest technology that pushes the limits of what we currently know about the drivers of desertification. Advancement could help us find more ways to prevent the issue from becoming an epidemic. 
8. Restricting Mining Practices 
Mining often implies the destruction of large areas of land. Therefore it should be regulated by governments to keep the nature reserves intact and protect the natural habitats of many animals and plants. Thus, fess land will be and, and the desertification issue can be mitigated to a certain extent. 
6. Putting Together Rehabilitation Efforts 
There are some ways that we can go back and rehabilitate the land that we've already pushed into desertification; it just takes some investment of time and money. By putting these together, we can prevent the issue from becoming even more widespread in the areas that have already been affected. 
7-Reforestation 
The areas that have been subject to deforestation in the past should be considered for reforestation. Planting trees in those areas are quite important since they are natural carbon dioxide storage spaces; they slow down global warming and contribute to maintaining 2 natural balance. Whereas using those areas for other purposes may turn them into land in the long run. Therefore, planting trees in the affected areas not only prevents desertification but also fights against additional environmental issues. 
8. Sustainable Practices to Prevent Desertification from Happening
There are plenty of sustainable practices that can be applied to these acts that may be causing desertification. By adding these to what we should be doing with land, we can ensure that we don’t tum the entire world into a desert.

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