1 / 84

Man- Environment Relationship

Man- Environment Relationship. HO Pui-sing. Contents. Modification of Landforms Modification of the Atmosphere Modification of Ecosystem Tropical Rain Forest Landscape Tropical Desert Landscape. Modification of Landforms. Mining, Quarrying, Deforestation, introduce new plants and animals

hu-alvarado
Download Presentation

Man- Environment Relationship

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Man- Environment Relationship HO Pui-sing

  2. Contents • Modification of Landforms • Modification of the Atmosphere • Modification of Ecosystem • Tropical Rain Forest Landscape • Tropical Desert Landscape

  3. Modification of Landforms • Mining, Quarrying, Deforestation, introduce new plants and animals • Direct affect on the shape of landforms: Excavating, reclaiming land… • Deforestation for agriculture and urbanization

  4. Deforestation • Natural vegetation • Regulator of natural erosion • Protecting the ground from raindrop • Absorbing runoff (Large infiltration capacity) • Making the slope more cohesive • Deforestation • Small infiltration capacity, more surface runoff, soil erosion in upper courses, increase sedimentation and floods in lower courses

  5. Deforestation – runoff and sediments

  6. Urbanization

  7. Modification of the Atmosphere • Sources: • Industrial Revolution • Mining and quarrying • Urbanization • Farming • Harmful effects: • Health • Pollution and Acid Rain • Climate changes

  8. Harmful effects - health • Many pollutants are irritant to eyes • Eg. Smoke, Ozone, Suspended particles… • Dangerous to the respiratory system • Eg. Lung Cancer

  9. Harmful effects – Pollution • Pollutants: • Solid: Smoke, Total suspended particles (TSP) • Liquid: Acid rain • Gaseous: sulphur dioxide (SO2), Carbon monoxide (CO), Oxides of nitrogen (NOx – NO, NO2)…..

  10. Harmful effects – climate changes • Change the composition of air • Increase CO2 Level (290ppm to 340ppm)

  11. Harmful effects – Climate changes • CO2 from fossil fuels combustion • CO2 level increase, O2 level decrease • CO2 is greenhouse gas • Affect global radiation and heat balances • Global temperature increase • Alter the rate of evapo-transpiration • Urbanization • Alter the surface nature & industrial activities • Heat Island effect (micro-climate)

  12. Modification of Ecosystem • Agriculture, Industries activities and Urbanization • Simplified ecosystems • Disrupted nutrient cycling • Introduced alien species • Eliminated original species • pollution

  13. Simplified ecosystem • Monoculture • High energy and materials (fertilizers) input • Destroys major nutrient reservoirs (biomass and soil) • Eutrophication – excess fertilizers added • Elimination species • Conscious - hunting • Unconscious – disruption of habitats • Decline efficiency – ecological imbalance

  14. Tropical Rain Forest Landscape • Where is Shifting Agriculture Practiced • Characteristics of Shifting Cultivation • The Relationship between SC and Env. • Opportunities and constraints posed by Env. • Response to the opportunities and constraints - Farm Cycle • Conclusion • Shifting Cultivation is Ecologically Destructive

  15. Distribution of Shifting cultivation Congo Basin Amazon Basin South-east Asia

  16. Characteristics of Shifting Cultivation • Primitive peoples’cultivation method • Subsistence farming with tuberous plants • “Slash and Burn” for clearing forest • Low man-land ratio • Primitive method with simple hand tools • Relatively low yields from crops supplementary with gathering • No fertilizers and pesticides added • Periodic migration leaving the clearing (2-3 years) • Extensive farming

  17. Relationship between SC and Env. • Tropical climate –high temp. and high rainfall • Rapid and high level nutrition cycle • Heavy leaching, Rapid chemical processes and bacterial activitieslitter and humus are quickly decomposeinfertile soil • Soil fertility maintain by efficient nutrient cycle and most nutrients are locked in biomass

  18. Relationship between SC and Env. • Shifting cultivator disrupts an ecosystem equilibrium • SC take the advantage of transient availability of nitrogen and carbon (nutrients) • Destroyed the nutrient cycle by clearing • Depleting effects are accelerated and soil becomes almost completely inorganic • Oxides layer of the soil expose to air becomes laterite • Lateritic crusts are hard, compact and very difficult to cultivate and increase surface runoff and soil erosion • Exposure to air, loss of humusincrease evaporation, raindrop effect and decrease field capacitysoil structure change

  19. Farm cycle – Response to the Env. • Selecting site • Clearing forest • Burning off the dead materials • Planting crops • Weeding and harvesting crops • Abandoning the clearing

  20. Selecting site • Fertile soil and ease of clearing • Primeval forest fertile soil • Few undergrowth under the dense canopy ease to clear • Some tribes prefer secondary forest (former site)

  21. Clearing forest • Clearing forest for having site for cultivation • Time: end of rainy season to the beginning of dry season • Lianas, undergrowth and sapling are hacked down. Trees are cut above buttress roots. • The largest trees may be spared for against soil erosion and they are hard to cut down • The dead vegetation is piled into heaps and dry out for one or two months.

  22. Burning off the dead vegetation • Late dry season will set on a fire to burn them off. • Fire is the easiest way to clear the site. • The largest trees left for shading for young plants • Advantages of burning: • Ashes are also fertility for soil • Potash, phosphates and decrease in soil acidity. • Break up the hard lateritic surface • Dry out the clay soil and develop large cracks into which the ashes accumulate • Burning debris helps to reduce runoff and soil erosion.

  23. Planting crops • Planting is usually timed to take full advantage of rainy season • Mixed cropping • Advantage of mixed cropping • maximum return and minimum effort. • Mixture of crops prevent weeds growth. • Different growth habits, root systems, demand on soil nutrient. • Insuranceagainst the failure of any one crop. • Practice crop rotation for more than one growing season

  24. Weeding and Harvesting • Minimal weeding • Almost no attention until harvest • Too much cultivation increases soil erosion

  25. Abandon and migration • 1 to 3 years, yields begin decline • Humus and ashesare thoroughly used and leach out without any replenishment • Weeds and undergrowth encroach seriously • Abandon the clearing and find another site for clearing and cropping.

  26. Abandon and migration – cont’d • Some tribes may plant tree crops (bananas and coconuts) before moving • More primitive peoples build only temporary villages for always moving. • The land will recover the fertility after a long period of time (about 20 years) • Clearing and migration are conservational measure to restore fertility to depleted soils.

  27. Conclusion • Shitting cultivation is a response to the harsh environment. • Subsistence farming with growing wide range of crops (tuberous plant) • It is a miniaturized tropical forest • ‘Slash and burn’ is a method to transfer the stored nutrients from biomass to soil. • Short period of cultivation and long period of fallowno permanent damage to the environment

  28. Conclusion – cont’d • Effective means of using rain forest env. and minimize the problems (soil erosion, soil fertility deterioration and vegetation degradation) • Pre-requisite: primitive technology, small population and sparse distribution.

  29. Case study • Note p.14-16 “Shifting Cultivation is ecologically destructive” • Main points (destroy old balance between man and nature) • Population increase demand of food increase • Introduce commercial concept – growing tree crops (rubber, coffee,….)for sell • Introduce European agricultural techniques and urban development • More lands for farming • Field works are left to women • Shorten the fallow (abandon) period • Serious soil depletion and soil erosion

  30. Impacts of Shifting Cultivation • The atmosphere • The hydrosphere • Soil • Vegetation and animals

  31. The Atmosphere • The global climate • TRF is a natural filter • It absorb CO2 and produce O2 through photosynthesis • Clearance of TRF, increase CO2 (greenhouse gas) content and lead to temperature increase and • Affect water budget: rainfall changes (increase or decrease)

  32. Atmosphere – cont’d • The micro-climate • Normal • Forest floor is moist, shade, temperature is relatively low (32oC), wind cannot penetrate and high humidity. • Clearance • Sunshine reaches the floor, temperature and soil temp. increase (65oC), increase evaporation, decrease relative humidity and increase wind speed

  33. The hydrosphere • Reduce interception and organic debris supply • Decrease infiltration capacity and increase surface runoff • River flow increase (volume, speed and silt load) • Water chemistry (increase solution load) • Shape and size of river channels (flooding and sedimentation)

  34. Soil • Increase leaching • Desilication and accumulation of sesquioxides • Laterization • Oxisolexpose to air and through desiccation to become harden layer –latertie. • Mechanism to check laterization in TRF • Trees supply plenty of organic matter • Slows down evaporation from soil

  35. Soil – cont’d • Break down the nutrient cycle • Release large amount of nutrients from biomass to soil by burning • Large amount of nutrients will be transform to ash which is loss by volatilization, wind deflation and water erosion. • Increase temperature lead to increase rate of decomposition and no humus can be accumulated • Runoff washes away the available nutrients • Soil become exhaustion and lead to soil erosion

  36. Soil – cont’d • Soil erosion • Ground become no protection for deforestation • No interception and rain drops directly on ground surface (rainsplash) to destroy soil structure • Decrease infiltration capacity and increase surface runoff • Rills, gullies to badland • Increase river loads and lead to sedimentation in lower course and causes reservoir silting, obstruct navigate, poor irrigation and flooding.

  37. Vegetation and animals • Rain forest was cleared and abandoned by man, secondary forest occurs. • The floristic andstructure are very different from the virgin forest • The different depends on • Availability of seeds of primary forest trees • Length of cultivation before abandonment

  38. Primary Forest

  39. Secondary Forest

  40. Vegetation and animals – cont’d • The different between secondary forest and primary forest • Secondary forest is lower and consists of trees of smaller average dimensions. • Very young secondary forest is remarkably regular and uniform structure (abundance of small climbers and young saplings) • Poorer in species (one or a small number) • Secondary forest vegetation is light demanding and intolerant of shade. • Growing very fast • Short-live, mature and reproduce early • Wood has a soft texture and low density

  41. Vegetation and animals – cont’d • Disturbing the ecological system • Rainforest lost: West Africa –72%, South east-Asia: 63.5% • TRF is the centre of the plant evolution of the world. Deforestation may change the future course of plant evolution. • Knowledge of plant physiology and ecology has been gained from studies in tropics. • Forest to agricultural, complex food web to simple food chain, encourage certain animals and insects species to multiply • Shifting agriculture becomesecologically destructive.

  42. Desert Landscape • Natural Environment • Nomadic Pastoralism • Problem of Over-grazing • Impacts of Over-grazing • Remedies to Desertification

  43. Global distribution of desert

  44. Natural Environment • Annual rainfallless than250 mm • Rainfall is insufficient • Erratic • Unpredictable • Vegetation is sparse and very localized • It is a harsh Environment • It is impossible for arable farming and very difficult to support domestic animals

  45. Desert Environment

More Related