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Environmental Changes and their Impact on Forest

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Climate change is affecting our natural environment. This presentation deals with understanding of effects of environmental changes on forests and mitigation methods.

Publié dans : Environnement
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Environmental Changes and their Impact on Forest

  1. 1. Presenter Malik Ghulam Asghar B.Sc. hons (Agronomy) Bahauddin Zakariya University Multan
  2. 2. Environmental change is defined as a change or disturbance of the environment caused by human influences or natural ecological processes. Environmental change can include any number of things, including: 1. natural disasters 2. human interference 3. animal interaction.
  3. 3. There are many different factors that affect environment around the world. 1. Green House Effect  Global Warming  Sea Level Rise  Glacier Melting  Acid Rain  Health Risks 2. Water Pollution  Causes  Effects  Health Risks 3. Soil Pollution  Causes  Effects  Health Risks
  4. 4. The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases.
  5. 5. A gradual increase in the overall temperature of the earth's atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide, CFCs, and other pollutants.
  6. 6.  Glaciers and ice shelves around the world are melting  The loss of large areas of ice on the surface could accelerate global warming because less of the sun's energy would be reflected away from Earth.  An immediate result of melting glaciers would be a rise in sea levels.  Initially, the rise in sea level would only be an inch or two. Even a modest rise in sea levels could cause flooding problems for low-lying coastal areas.  However, if the West Antarctic Ice Sheet were to melt and collapse into the sea, it would push sea levels up 10 meters (more than 32 feet), and many coastal areas would completely disappear beneath the ocean
  7. 7.  Acid Rain on the Forest Floor  How Acid Rain Harms Trees  How Acid Rain Affects Other Plants
  8. 8.  A spring shower in the forest washes leaves and falls through the trees to the forest floor below.  Some trickles over the ground and runs into streams, rivers, or lakes, and some of the water soaks into the soil.  That soil may neutralize some or all of the acidity of the acid rainwater. This ability is called buffering capacity, and without it, soils become more acidic.  Differences in soil buffering capacity are an important reason why some areas that receive acid rain show a lot of damage, while other areas that receive about the same amount of acid rain do not appear to be harmed at all.
  9. 9.  Acid rain does not usually kill trees directly. Instead, it is more likely to weaken trees by damaging their leaves, limiting the nutrients available to them, or exposing them to toxic substances slowly released from the soil.  At the same time, acid rain causes the release of substances that are toxic to trees and plants, such as aluminum, into the soil.  Loss of soil nutrients and increase of toxic aluminum may be one way that acid rain harms trees. Such substances also wash away in the runoff and are carried into streams, rivers, and lakes.  Trees can be damaged by acid rain even if the soil is well buffered. Forests in high mountain regions often are exposed to greater amounts of acid than other forests because they tend to be surrounded by acidic clouds and fog that are more acidic than rainfall.  When leaves are frequently bathed in this acid fog, essential nutrients in their leaves and needles are stripped away.
  10. 10.  Acid rain can harm other plants in the same way it harms trees.  Although damaged by other air pollutants such as ground level ozone, food crops are not usually seriously affected because farmers frequently add fertilizers to the soil to replace nutrients that have washed away.  They may also add crushed limestone to the soil.  Limestone is an alkaline material and increases the ability of the soil to act as a buffer against acidity.
  11. 11.  Acids have a corrosive effect on limestone or marble buildings or sculptures. It is well established that either wet or dry deposition of sulfur dioxide significantly increases the rate of corrosion on limestone, sandstone, and marble.  sulfur dioxide plus water makes sulfurous acid SO2 + H2O --> H2SO3  sulfur trioxide plus water makes sulfuric acid SO3 + H2O --> H2SO4 
  12. 12. Climate change is expected to affect air quality through several pathways, including production and allergenicity of allergens and increase regional concentrations of ozone, fine particles, and dust. Some of these pollutants can directly cause respiratory disease or exacerbate existing conditions in susceptible populations, such as children or the elderly.
  13. 13. Water pollution is the contamination of water bodies(e.g. lakes, rivers, oceans, aquifers and gro undwater).Water pollution occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds.
  14. 14.  Sewage and Wastewater  Marine dumping  Industrial water and water pollution  Nuclear waste – how it is produced  Oil pollution  Underground storage leakages  Atmospheric  Global Warming  Eutrophication
  15. 15.  Domestic households, industrial and agricultural practices produce wastewater that can cause pollution of many lakes and rivers.  Sewage is the term used for wastewater that often contains faeces, urine and laundry waste.  There are billions of people on Earth, so treating sewage is a big priority.  Sewage disposal is a major problem in developing countries as many people in these areas don’t have access to sanitary conditions and clean water.  Untreated sewage water in such areas can contaminate the environment and cause diseases such as diarrhoea.  Sewage in developed countries is carried away from the home quickly and hygienically through sewage pipes.
  16. 16.  Dumping of litter in the sea can cause huge problems. Litter items such as 6-pack ring packaging can get caught in marine animals and may result in death. Different items take different lengths of time to degrade in water:  Cardboard – Takes 2 weeks to degrade.  Newspaper – Takes 6 weeks to degrade.  Photodegradable packaging – Takes 6 weeks to degrade.  Foam – Takes 50 years to degrade.  Styrofoam – Takes 80 years to degrade.  Aluminium – Takes 200 years to degrade.  Plastic packaging – Takes 400 years to degrade.  Glass – It takes so long to degrade that we don’t know the exact time.
  17. 17.  Industry is a huge source of water pollution, it produces pollutants that are extremely harmful to people and the environment.  Many industrial facilities use freshwater to carry away waste from the plant and into rivers, lakes and oceans.  Pollutants from industrial sources include:  Asbestos  Lead  Mercury  Nitrates  Phosphates  Sulphur  Oils  Petrochemicals
  18. 18.  Nuclear waste is produced from industrial, medical and scientific processes that use radioactive material. Nuclear waste can have detrimental effects on marine habitats. Nuclear waste comes from a number of sources:  Operations conducted by nuclear power stations produce radioactive waste. Nuclear-fuel reprocessing plants in northern Europe are the biggest sources of man-made nuclear waste in the surrounding ocean. Radioactive traces from these plants have been found as far away as Greenland.  Mining and refining of uranium and thorium are also causes of marine nuclear waste.  Waste is also produced in the nuclear fuel cycle which is used in many industrial, medical and scientific processes.
  19. 19.  Oceans are polluted by oil on a daily basis from oil spills, routine shipping, run-offs and dumping.  Oil spills make up about 12% of the oil that enters the ocean. The rest come from shipping travel, drains and dumping.  An oil spill from a tanker is a severe problem because there is such a huge quantity of oil being spilt into one place.  Oil spills cause a very localised problem but can be catastrophic to local marine wildlife such as fish, birds and sea otters.  Oil cannot dissolve in water and forms a thick sludge in the water. This suffocates fish, gets caught in the feathers of marine birds stopping them from flying and blocks light from photosynthetic aquatic plants.
  20. 20.  A tank or piping network that has at least 10 percent of its volume underground is known as an underground storage tank (UST). They often store substances such as petroleum, that are harmful to the surrounding environment should it become contaminated. Many UST’s constructed before 1980 are made from steel pipes that are directly exposed to the environment. Over time the steel corrodes and causes leakages, affecting surrounding soil and groundwater.
  21. 21.  Atmospheric deposition is the pollution of water caused by air pollution.  In the atmosphere, water particles mix with carbon dioxide sulphur dioxide and nitrogen oxides, this forms a weak acid.  Air pollution means that water vapour absorbs more of these gases and becomes even more acidic.  When it rains the water is polluted with these gases, this is called acid rain.  When acid rain pollutes marine habitats such as rivers and lakes, aquatic life is harmed.
  22. 22.  An increase in water temperature can result in the death of many aquatic organisms and disrupt many marine habitats. For example, a rise in water temperatures causes coral bleaching of reefs around the world. This is when the coral expels the microorganisms of which it is dependent on. This can result in great damage to coral reefs and subsequently, all the marine life that depends on it.  The rise in the Earth’s water temperature is caused by global warming.  Global warming is a process where the average global temperature increases due to the greenhouse effect.  The burning of fossil fuel releases greenhouse gasses, such as carbon dioxide, into the atmosphere.  This causes heat from the sun to get ‘trapped’ in the Earths atmosphere and consequently the global temperature rises.
  23. 23.  Eutrophication is when the environment becomes enriched with nutrients. This can be a problem in marine habitats such as lakes as it can cause algal blooms.  Fertilizers are often used in farming, sometimes these fertilisers run- off into nearby water causing an increase in nutrient levels.  This causes phytoplankton to grow and reproduce more rapidly, resulting in algal blooms.  This bloom of algae disrupts normal ecosystem functioning and causes many problems.  The algae may use up all the oxygen in the water, leaving none for other marine life. This results in the death of many aquatic organisms such as fish, which need the oxygen in the water to live.  The bloom of algae may also block sunlight from photosynthetic marine plants under the water surface.  Some algae even produce toxins that are harmful to higher forms of life. This can cause problems along the food chain and affect any animal that feeds on them.
  24. 24. Soil pollution is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals, or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons (such as naphthalene andbenzo (a) pyrene), solvents, pesticides, lead, and other heavy metals. Contamination is correlated with the degree of industrialization and intensity of chemical usage
  25. 25.  Soil pollution can be caused by the following  Accidental Spills  Acid rain  Intensive farming  Deforestation  Genetically modified plants  Nuclear wastes  Industrial Accidents  Landfill and illegal dumping  Pesticides, herbicides and fertilizers  Mining and other industries  Oil and fuel dumping  Buried wastes  Disposal of coal ash
  26. 26.  Historical deposition of coal ash used for residential, commercial, and industrial heating, as well as for industrial processes such as ore smelting, were a common source of contamination in areas that were industrialized before about 1960.  Coal naturally concentrates lead and zinc during its formation, as well as other heavy metals to a lesser degree.  When the coal is burned, most of these metals become concentrated in the ash (the principal exception being mercury).  Coal ash and slag may contain sufficient lead to qualify as a "characteristic hazardous waste", defined in the USA as containing more than 5 mg/L of extractable lead using the TCLP procedure.  In addition to lead, coal ash typically contains variable but significant concentrations of polynuclear aromatic hydrocarbons (PAHs; e.g., benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(cd)pyrene, phenanthrene, anthracene, and others).
  27. 27.  Treated sewage sludge, known in the industry as biosolids, has become controversial as a fertilizer to the land. As it is the byproduct of sewage treatment, it generally contains more contaminants such as organisms, pesticides, and heavy metals than other soil.  In the European Union, the Urban Waste Water Treatment Directive allows sewage sludge to be sprayed onto land.  The volume is expected to double to 185,000 tons of dry solids in 2005.  This has good agricultural properties due to the high nitrogen and phosphate content.  In 1990/1991, 13% wet weight was sprayed onto 0.13% of the land; however, this is expected to rise 15 fold by 2005.
  28. 28.  Pesticide is a substance or mixture of substances used to kill a pest.  A pesticide may be a chemical substance, biological agent (such as a virus or bacteria), antimicrobial, disinfectant or device used against any pest. Pests include insects, plant pathogens, weeds, mollusks, birds, mammals, fish, nematodes (roundworms) and microbes that compete with humans for food, destroy property, spread or are a vector for disease or cause a nuisance.  Although there are benefits to the use of pesticides, there are also drawbacks, such as potential toxicity to humans and other organisms.  Herbicides are used to kill weeds, especially on pavements and railways.  One group derived from trinitrotoluene (2:4 D and 2:4:5 T) have the impurity dioxin, which is very toxic and causes fatality even in low concentrations.
  29. 29.  Effect on Growth of Plants  Health effects due to Soil Pollution
  30. 30.  The ecological balance of any system gets affected due to the widespread contamination of the soil.  Most plants are unable to adapt when the chemistry of the soil changes so radically in a short period of time.  Fungi and bacteria found in the soil that bind it together begin to decline, which creates an additional problem of soil erosion.  The fertility slowly diminishes, making land unsuitable for agriculture and any local vegetation to survive.  The soil pollution causes large tracts of land to become hazardous to health.  Unlike deserts, which are suitable for its native vegetation, such land cannot support most forms of life.
  31. 31.  Contaminated or polluted soil directly affects human health through direct contact with soil or via inhalation of soil contaminants which have vaporized; potentially greater threats are posed by the infiltration of soil contamination into groundwater aquifers used for human consumption, sometimes in areas apparently far removed from any apparent source of above ground contamination.  Chronic exposure to chromium, lead and other metals, petroleum, solvents, and many pesticide and herbicide formulations can be carcinogenic, can cause congenital disorders, or can cause other chronic health conditions.  Industrial or man-made concentrations of naturally occurring substances, such as nitrate and ammonia associated with livestock manure from agricultural operations, have also been identified as health hazards in soil and groundwater.
  32. 32.  Chronic exposure to benzene at sufficient concentrations is known to be associated with higher incidence of leukemia.  Mercury and cyclodienes are known to induce higher incidences of kidney damage, some irreversible.  PCBs and cyclodienes are linked to liver toxicity.  Organophosphates and carbomates can induce a chain of responses leading to neuromuscular blockage.  Many chlorinated solvents induce liver changes, kidney changes and depression of the central nervous system.  There is an entire spectrum of further health effects such as headache, nausea, fatigue, eye irritation and skin rash for the above cited and other chemicals.  At sufficient dosages a large number of soil contaminants can cause death by exposure via direct contact, inhalation or ingestion of contaminants in groundwater contaminated through soil.
  33. 33.  Loss of habitat  Drives climate change  Deprives the forest  Speed and severity of global warming.  carbon sink
  34. 34. Deforestation has many negative effects on the environment. The most dramatic impact is a loss of habitat for millions of species. Seventy percent of Earth’s land animals and plants live in forests, and many cannot survive the deforestation that destroys their homes.
  35. 35. Deforestation also drives climate change. Forest soils are moist, but without protection from sun-blocking tree cover they quickly dry out. Trees also help perpetuate the water cycle by returning water vapor back into the atmosphere. Without trees to fill these roles, many former forest lands can quickly become barren deserts.
  36. 36. Removing trees deprives the forest of portions of its canopy, which blocks the sun’s rays during the day and holds in heat at night. This disruption leads to more extreme temperatures swings that can be harmful to plants and animals.
  37. 37. Trees also play a critical role in absorbing the greenhouse gases that fuel global warming. Fewer forests means larger amounts of greenhouse gases entering the atmosphere— and increased speed and severity of global warming.
  38. 38. A carbon sink is a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period. The process by which carbon sinks remove carbon dioxide (CO2) from the atmosphere is known as carbon sequestration.
  39. 39. Forests as a carbon sink are often overlooked as a major source of carbon removal from the atmosphere, a process known as carbon sequestration. Conversely , deforestation, whether removal of forests by logging or burning, has been a major contribution to atmospheric carbon addition. There are two main reasons for land use conversion by deforestation; ranching and agriculture. These conversions are done in an attempt to produce short term economic benefit by forcing immediate environmental change. Cattle ranching is one of the leading causes of deforestation.
  40. 40.  Afforestation is the establishment of a forest or stand of trees in an area where there was no forest.  Reforestation is the reestablishment of forest cover, either naturally (by natural seeding, coppice, or root suckers) or artificially (by direct seeding or planting). Many governments and non-governmental organizations directly engage in programs of afforestation to create forests, increase carbon capture and sequestration, and help to anthropogenically improve biodiversity
  41. 41.  In a natural forest or woodland, the trees are heterogeneous. Owing to the sensitivity to over usage and slow growths, these forests cannot be used continuously for commercial purposes like wood products.  The process of planting trees in empty lands helps promote the fast propagation of specific types of trees for the wood industry. With the increasing demand for wood fuels and building materials, this process helps to meet these demands without cutting down the natural forests.  Afforestation ensures trees and plants that hold the soil in these sensitive areas remain protected.
  42. 42. Many countries have introduced the practice of planting trees along with agricultural crops in croplands. The benefits of this practice, which is called agroforestry, are:  It provides a supply of timber, fruit, and fodder for cattle apart from crop production  It prevents soil erosion  It enables better retention of water  It shields crops from excessive wind and sun damage  In terms of the environmental benefits, planting trees is always beneficial whether it takes place in a barren land or is used as a method to regenerate a depleted forest.  Trees help check atmospheric carbon dioxide; large scale afforestation can curb the problems caused due to burning of fossil fuels, industrialization and so forth.

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