Presentation on theme: "FORESTRY Dr VISHAL SHARMA ASSOC.PROF. BOTANY DEPARTMENT, POST GRADUATE GOVERNMENT COLLEGE FOR GIRLS-11, CHANDIGARH."— Presentation transcript:
FORESTRY Dr VISHAL SHARMA ASSOC.PROF. BOTANY DEPARTMENT, POST GRADUATE GOVERNMENT COLLEGE FOR GIRLS-11, CHANDIGARH
Forsetry stands for the theory and practice of constitution and management of forests and utilization of their products. Forestry has different branches: (1)Mensuration: It deals with the measurement of forest produce (2)Management: It is a practical application of science,technology and economicsto a forest estata for the production of certain desired results. (3)Silviculture: It refers to certain aspects of theory and practice of raising crops,trees,their growth and care upto harvesting. (4)Utilization:It is the branch ofForestry which deals with the harvesting,marketing, conversion and applying the forest produce to a variety of uses
What are the Causes of Deforestation? The destruction of the forests is occurring due to various reasons, one of the main reasons being the short term economic benefits. Given below are some more common causes of deforestation: Used for Urban and Construction Purposes: The cutting down of trees for lumber that is used for building materials, furniture, and paper products. Forests are also cleared in order to accommodate expanding urban areas. To Grow Crops: Forests are also cut down in order to clear land for growing crops. To Create Grazing Land: Forests are cut down in order create land for grazing cattle. Used for Fuel: Trees are cut down in developing countries to be used as firewood or turned into charcoal, which are used for cooking and heating purposes. Some of the other causes of deforestation are: clearing forests for oil and mining exploitation; to make highways and roads; slash and burn farming techniques; wildfires; and acid rain.
What are the Effects of Deforestation? There are a number of adverse effects of deforestation, such as: Erosion of Soil: When forest areas are cleared, it results in exposing the soil to the sun, making it very dry and eventually, infertile, due to volatile nutrients such as nitrogen being lost. In addition, when there is rainfall, it washes away the rest of the nutrients, which flow with the rainwater into waterways. Because of this, merely replanting trees may not help in solving the problems caused by deforestation, for by the time the trees mature, the soil will be totally devoid of essential nutrients. Ultimately, cultivation in this land will also become impossible, resulting in the land becoming useless. Large tracts of land will be rendered permanently impoverished due to soil erosion. Disruption of the Water Cycle: Trees contribute in a large way in maintaining the water cycle. They draw up water via their roots, which is then released into the atmosphere. A large part of the water that circulates in the ecosystem of rainforests, for instance, remains inside the plants. When these trees are cut down it results in the climate getting drier in that area. Loss of Biodiversity: The unique biodiversity of various geographical areas is being lost on a scale that is quite unprecedented. Even though tropical rainforests make up just 6 percent of the surface area of the Earth, about 80-90 percent of the entire species of the world exist here. Due to massive deforestation, about 50 to 100 species of animals are being lost each day. The outcome of which is the extinction of animals and plants on a massive scale
Flooding and Drought: One of the vital functions of forests is to absorb and store great amounts of water quickly when there are heavy rains. When forests are cut down, this regulation of the flow of water is disrupted, which leads to alternating periods of flood and then drought in the affected area. Climate Change: It is well known that global warming is being caused largely due to emissions of greenhouse gases like carbon dioxide into the atmosphere. However, what is not known quite as well is that deforestation has a direction association with carbon dioxide emissions into the atmosphere. Trees act as a major storage depot for carbon, since they absorb carbon dioxide from the atmosphere, which is then used to produce carbohydrates, fats, and proteins that make up trees. When deforestation occurs, many of the trees are burnt or they are allowed to rot, which results in releasing the carbon that is stored in them as carbon dioxide. This, in turn, leads to greater concentrations of carbon dioxide in the atmosphere ATMOSPHERIC ROLE OF FORESTS Rainforests play the important role of locking up atmospheric carbon in their vegetation via photosynthesis. The vegetation and soils of the world's forests contain about 125% of the carbon found in the atmosphere. When forests are burned, degraded, or cleared, the opposite effect occurs: large amounts of carbon are released into the atmosphere as carbon dioxide along with other greenhouse gases (nitrous oxide, methane, and other nitrogen oxides). The burning of forests releases almost one billion tons of carbon dioxide into the atmosphere each year.containreleases
The buildup of carbon dioxide and other gases in the atmosphere is known as the "greenhouse effect." The buildup of these gases is believed to have altered the earth's radiative balance meaning more of the sun's heat is absorbed and trapped inside the earth's atmosphere, producing global warming. The largest anthropogenic contributor to the greenhouse effect is carbon dioxide gas emissions, 73-92% of which comes from the combustion of fossil fuels, 13-23% of which is attributed to deforestation, and the final 1% coming primarily from energy costly production activities like the manufacture of concrete, steel, and aluminum.greenhouse effectemissions The extent and effect of global warming has been long debated by scientists, industries, and politicians. In 1995 leading scientists, the Intergovernmental Panel on Climate Change (IPCC) concluded that global warming had been detected and that "the balance of evidence suggests a discernible human influence of global climate." Their evidence included a 0.5-1F (0.3 to 0.6C) increase in average global temperature, a 4.5F (2.5C) degree increase at the Earth's poles, the breaking up of the Antarctic ice sheets, the receding of glaciers worldwide, the longest El Niño ever recorded, a record number of hurricanes in 1995, a record number of heat waves, and an increase of epidemics attributed to global climate change including dengue fever, malaria, hanta virus, and the plague.debatedEl Niño
The water cycle is also affected by deforestation. Trees extract groundwater through their roots and release it into the atmosphere. When part of a forest is removed, the trees no longer evaporate away this water, resulting in a much drier climate. Deforestation reduces the content of water in the soil and groundwater as well as atmospheric moisture.Deforestation reduces soil cohesion, so that erosion, flooding and landslides ensue.Forests enhance the recharge of aquifers in some locales, however, forests are a major source of aquifer depletion on most locales. Shrinking forest cover lessens the landscape’s capacity to intercept, retain and transpire precipitation. Instead of trapping precipitation, which then percolates to groundwater systems, deforested areas become sources of surface water runoff, which moves much faster than subsurface flows. That quicker transport of surface water can translate into flash flooding and more localized floods than would occur with the forest cover. Deforestation also contributes to decreased evapotranspiration, which lessens atmospheric moisture which in some cases affects precipitation levels downwind from the deforested area, as water is not recycled to downwind forests, but is lost in runoff and returns directly to the oceans. According to one study, in deforested north and northwest China, the average annual precipitation decreased by one third between the 1950s and the 1980s.
One of the maincauses of Global Warming is the Green house effect. When the emission of infra-red radiation in the atmosphere warms a planet's surface, it is known as the Green House Effect. The Greenhouse effect is a natural phenomena occurring on planet Earth. 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, energy is transferred to the surface and the lower atmosphere. As a result, the temperature there is higher than it would be if direct heating by solar radiation were the only warming mechanism. The greenhouse effect is actually beneficial to the Earth. It is only when human-made processes increase its speed that the problems occur. One main problem is the oft repeated 'Global Warming'.
Man-made causes: (i) deforestation - increases the amount of carbon dioxide in the atmosphere - due to the disappearance of trees, photosythesis cannot take place. - levels of deforestation have increased by about nine percent in recent times. - burning of wood causes it to decay,therefore releasing more carbon-dioxide into the atmosphere. (ii) Emission of gases due to the burning of fossil fuels, oil, coal and gas (iii) Electrical appliances - gases are known as Chloroflourocarbons (CFCs) - used in refrigerators, aerosol cans, some foaming agents in the packaging industry, fire extinguisher chemicals and cleaners used in the electronic industry - some processes of the cement manufacturing industries also act as a cause towards the Greenhouse effect
Deforestation is one of the major factor for Global warming. Government across the globe should stop deforestation immediately to save our ear th.
Effect of deforestation on Global warming: Deforestation is a contributor to global warming,and is often cited as one of the major causes of the enhanced greenhouse effect. Tropical deforestation is responsible for approximately 20% of world greenhouse gas emissions. According to the Intergovernmental Panel on Climate Change deforestation, mainly in tropical areas, could account for up to one-third of total anthropogenic carbon dioxide emissions. But recent calculations suggest that carbon dioxide emissions from deforestation and forest degradation (excluding peatland emissions) contribute about 12% of total anthropogenic carbon dioxide emissions with a range from 6 to 17%. Trees and other plants remove carbon (in the form of carbon dioxide) from the atmosphere during the process of photosynthesis and release oxygen back into the atmosphere during normal respiration. Only when actively growing can a tree or forest remove carbon over an annual or longer timeframe. Both the decay and burning of wood releases much of this stored carbon back to the atmosphere. In order for forests to take up carbon, the wood must be harvested and turned into long-lived products and trees must be re-planted. Deforestation may cause carbon stores held in soil to be released. Forests are stores of carbon and can be either sinks or sources depending upon environmental circumstances. Mature forests alternate between being net sinks and net sources of carbon dioxide.
The Chipko movement or Chipko Andolan (literally "to stick" in Hindi) is a social-ecological movement that practised the Gandhian methods of satyagraha and non-violent resistance, through the act of hugging trees to protect them from falling. The modern Chipko movement started in the early 1970s in the Garhwal Himalayas of Uttarakhand,ith growing awareness towards rapid deforestation. The landmark event in this struggle took place on March 26, 1974, when a group of peasant women in Reni village, Hemwalghati, in Chamoli district, Uttarakhand, India, acted to prevent the cutting of trees and reclaim their traditional forest rights that were threatened by the contractor system of the state Forest Department. Their actions inspired hundreds of such actions at the grassroots level throughout the region.Hindisocial-ecological GandhiansatyagrahaGarhwalHimalayasUttarakhandChamoli districtUttarakhand The Chipko movement, though primarily a livelihood movement rather than a forest conservation movement, went on to become a rallying point for many future environmentalists, environmental protests and movements the world over and created a precedent for non-violent protest. Its success meant that the world immediately took notice of this non-violent Tree hugging movement, which was to inspire in time many such eco-groups by helping to slow down the rapid
Wood Seasoning is a process to stabilise the moisture content in the wood..Afinal moisture content of 7-12% is desirable There are four methods of seasoning wood: (1)Immersion method (2)Mechanical seasoning (3)Air seasoning (4)Klin seasoning
Figure : Wood before seasoning (left) and after seasoning (right)
The process of kiln drying consists basically of introducing heat. This may be directly, using natural gas and/or electricity or indirectly, through steam-heated heat exchangers, although solar energy is also possible. In the process, deliberate control of temperature, relative humidity and air circulation is provided to give conditions at various stages (moisture contents or times) of drying the timber to achieve effective drying. For this purpose, the timber is stacked in chambers, called wood drying kilns, which are fitted with equipment for manipulation and control of the temperature and the relative humidity of the drying air and its circulation rate through the timber stack Kiln drying provides a means of overcoming the limitations imposed by erratic weather conditions. In kiln drying as in air drying, unsaturated air is used as the drying medium. Almost all commercial timbers of the world are dried in industrial kilns. A comparison of air drying, conventional kiln and solar drying is given below: Timber can be dried to any desired low moisture content by conventional or solar kiln drying, but in air drying, moisture contents of less than 18% are difficult to attain for most locations. The drying times are considerably less in conventional kiln drying than in solar kiln drying, followed by air-drying. On the other hand, installing an industrial kiln, to say nothing of maintenance and operation, is expensive. In addition, wood that is being air-dried takes up space, which could also cost money. In air-drying, there is little control over the drying elements, so drying degrade cannot be controlled
Wood preservation All measures that are taken to ensure a long life of wood fall under the definition wood preservation (timber treatment). Apart from structural wood preservation measures, there are a number of different (chemical) preservatives and processes (also known aschemicalpreservatives timber treatment or lumber treatment) that can extend the life of wood, timber, woodwoodtimber structures or engineered wood. These generally increase the durability and resistanceengineered wooddurability from being destroyed by insects or fungusinsectsfungus Creosote is a wood preservative used for commercial purposes only; it has no registered residential uses. Creosote is obtained from high temperature distillation of coal tar (itself a mixture of hundreds of organic substances), and over 100 components in creosote have been identified. It is used as a fungicide, insecticide, miticide, and sporicide to protect wood and is applied by pressure methods to wood products, primarily utility poles and railroad. Coal-tar creosote Creosote is a tar-based preservative that has been commonly used for telephone poles and railroad ties. Creosote is one of the oldest wood preservatives, and was originally derived from a wood distillate. These days virtually all creosote is manufactured from the distillation of coal tar. It often collects inside chimneys and may cause a fire hazard. Creosote is regulated as a pesticide and is not usually sold to the general public. It is still used for railroad ties (also called railway sleepers and cross ties) and utility polestartelephone polesrailroad tiesCreosotechimneysrailroad tiesutility poles
Linseed oil Linseed oil has been incorporated in preservative formulations as a solvent and water repellent to 'envelope treat' timber. This involves just treating the outer 5 mm of the cross-section of a timber member with preservative (e.g., Permethrin 25:75), leaving the core untreated. Linseed oil is used to preserve Wood fences, log cabins, and wood furniture. (Such woods as Willow, Pine, oak and exc.) The function of linseed oil as a preservative is believed to be related to its action as a water repellent and drying agent rather than a direct biocidal activity. Fire retardant treated This treated wood utilizes a fire retardant chemical that remains stable in high temperature environments. The fire retardant is applied under pressure at a wood treating plant like the preservatives described above, or applied as a surface coating. In both cases, treatment provides a physical barrier to flame spread. The treated wood chars but does not oxidize. Effectively this creates a convective layer that transfers flame heat to the wood in a uniform way which significantly slows the progress of fire to the material. Some site-applied coatings as well as brominated fire retardants have lost favor due to safety concerns as well as concerns surrounding the consistency of application.
Borate preservatives Boric acid, oxides and salts (borates) are effective wood preservatives and are supplied under numerous brand names throughout the world. Borate treated wood is of low toxicity to humans, and does not contain copper or other heavy metals. However, unlike most other preservatives, borate compounds do not become fixed in the wood and can readily be leached out. Therefore they should not be used where they will be exposed to rain, water or ground contact. Recent interest in low toxicity timber for residential use, along with new regulations restricting some wood preservation agents, has resulted in a resurgence of the use of borate treated wood for floor beams and internal structural members. Sodium silicate-based preservatives Sodium silicate is produced by fusing sodiumwith sand or heating both ingredients under pressure. It has been in use since the 19th century. It can be a deterrent against insect attack and possesses minor flame resistant properties; however, it is easily washed out of wood by moisture, forming a flake-like layer on top of the wood. Potassium silicate-based preservatives There are a number of European natural paint fabricants that have developed potassium silicate (potassium waterglass) based preservatives. They frequently include boron compounds, cellulose, lignin and other plant extracts. They are a surface application with a minimal impregnation for internal use