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Earth: Our Home Full Geography Chapter 9 Types of Natural Vegetation

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1Earth: Our Home FuII GeographyChapter 9Types of NaturaI Vegetation2ou wiII Iearn: to describe the global distribution of different types of forests to describe the characteristics of different types of forests to compare the ways in which different types of forests adapt to the environment

hat is NaturaI Vegetation? Natural vegetation refers to plants that grow naturally in a place with little or no human interference. t plays an important role in a forestecosystem by providing food and shelter for the animals and native people that live in the forest.

ajor types of naturaI vegetationTropical rainforestTemperate deciduous forestConiferous forestGrassland biomeGrasses constitute the main plants in a grassland biome. It hasIew varieties oI plants.Tropical grassland Temperate grasslandDesert biomeThe vegetation in a desert biome consists oI mainly sparse vegetation, such as scrubs and tough grasses in the hot desert, and mosses and lichens in the cold desert. It has very Iew varieties oI plants.Hot desert vegetationCold desertvegetation (tundra)Forest biomeThe vegetation in a Iorest biome consists oI mainly trees. It generally has many varieties oI plants.

istribution of NaturaI Vegetation Climate is a major factor in influencing the distribution of natural vegetation. There areclimatic types..

istribution of NaturaI Vegetation'ery low temperatures, oIten below 0C. 'ery low annual precipitation, below 250 mmLow to modern temperatures, ranging Irom 0C to 34C, depending on the season. Moderate annual precipitation, 300 mm to 1 000 mmHigh temperatures throughout the year, 20C to 30C.High precipitation, above 1 000 mmTemperate regionPolar regionTropical regionTropical regionTemperate regionPolar region

istribution of NaturaI Vegetation Temperature and precipitation can influence plant growth. Plant growth is more abundant in areas where temperatures are consistently above 20HC than in areas where temperatures fall below HC.

istribution of NaturaI Vegetation Water is required by plants to make food. Thus, different types of natural vegetation forests are found in different parts of the world.- forests --- high precipitation at above1 000 mm per year. - grasslands --- moderate precipitationbetween 200 mm to 1 000 mm per year.- hot desert vegetation or tundra --- no orlittle precipitation at less than 20 mm peryear.

istribution of NaturaI Vegetation10TropicaI forests are a cradIe of biodiversity. It has been estimated that haIf of the pIant and animaI Iife forms that Iive on this pIanet are found in this environment, even though tropicaI forests cover onIy six percent of the earth's surface. Source: The TropicaI Rainforest by Francesco Petretti, Journey Editions, 1998, ItaIy.11TropicaI Rainforest Tropical rainforests- found in places that experience thetropical equatorial climate- high temperatures, about 2HC - high amount of rainfall, above 1 00 mm throughout the year- examples of tropical rainforests includethe Amazon Basin in South America,Congo Basin in Africa and parts ofSoutheast Asia12TropicaI Rainforest Structure of the forest- layers:- Emergent layer, 0 m to 0 m- Canopy layer, 1 m to 0 m- Understorey layer,m to 1 m- Shrub layer, grow up tom- Undergrowth layer, grow up to m1TropicaI Rainforestmergent layer 50 mTall trees, called emergents, reach a height oI 30 m to 50 m. Their crowns appear above the canopy layer. These trees have tall, thick and straight trunks.30 mCanopy layerThe trees in this layer reach a heightoI 15 m to 30 m. Their wide, shallow and umbrella-shapedcrowns Iorm a continuousleaI cover, called a canopy, as they preventsunlightIrom penetratinginto the lower layers oI the Iorest. 15 mUnderstorey layerThe trees here have narrower, oval-shapedcrowns because most oI the sunlightis blocked by the canopy. These trees grow where gaps in the canopy allow sunlightto pass through.Their heights range Irom 6 m to 15 m. Young trees oI the emergentand canopy layers are also Ioundin this layer.6 mShrub layerTree saplings and woodyplants are Ioundin this layer. They may grow up to 6 m high.5 mUndergrowth layerThe undergrowth or Iorest Iloor is made up oI grasses, Ierns, mosses and Iungi.Plant growth is sparse because very little sunlightreaches this layer. Plants in this layer reach a maximumheight oI 5 m.0 m1TropicaI Rainforest Characteristics of thelayersEmergent Iayer- trees have tall, thick and straight trunksCanopy Iayer- tree crowns inter-lock- presence of epiphytes and lianas, and parasitic plantsUnderstorey Iayer- trees with narrower crowns- presence of parasitic plantsShrub Iayer- tree saplings and woody plants foundUndergrowth Iayer- sparse due to lack of sunlight that reaches the forest floor1TropicaI Rainforest Characteristics- a wide diversity of plant species-0 species of trees and 1 00 species of other plantsin 1 hectare- the high temperature and rainfall throughout the yearenables it to support a large variety of plants ensity- extremely dense- density is due to high temperature and rainfall thatencourage abundant vegetation growth1TropicaI Rainforest Characteristics and AdaptationsLeaves- are evergreens - due to high rainfaII throughout theyear, trees do not shed Ieaves at thesame time- are waxy with drip tips- to aIIow rainwater to drain off easiIy1TropicaI Rainforest Characteristics and AdaptationsFIowers and fruits- are colourful and sweet-smelling - to attract insects for pollination andanimals for seed dispersal1"uick "uiz Can you identify the flower?1"uick "uiz t is a type of Rafflesia, a spectacular plant found in the tropical rainforest. There are 1 to 1 species of Rafflesia. Rafflesia is known to produce the largest individual flower on the Earth.20TropicaI rainforest Characteristics and AdaptationsBark and branches- thin and smooth branches- does not need protection against cold or dry conditions- branches are found at the uppermost one-third of thetrunks to get as much sunlight as possibleRoots- shallow and spreading- nutrients are found at topsoil due to high decomposition - buttress roots (of some tall trees)- support weight of trees21TropicaI onsoon Forest Tropical monsoon forest- found in the tropics- high temperatures, about 2HC - high amount of rainfall, above 1 00 mmthroughout the year, but with distinct wetand dry seasons- located in South Asia, SoutheastAsia,southern China and northernAustralia 22TropicaI onsoon ForestW istribution2TropicaI onsoon Forest Structure of the forest layers: - Canopy layer, 2 m to 0 m- Understorey layer, about 1 m- Undergrowth layer2TropicaI onsoon Forest0 mCanopy IayerTrees can grow to 2 to 0 min height. They are morespread out than those in atropical rainforests, plants suchas creepers, vines, epiphytes and parasitic plants are found within this layer.1 mUnderstorey IayerThe trees in theunderstorey are about 1 m in height. mUndergrowthBamboo thickets and grassesgrow densely here during thewet season. They are dense during the dry season.0 m2TropicaI onsoon Forest Characteristics of the 3 IayersCanopy Iayer- more spread out than those in tropical rainforest- presence of epiphytes and lianas, and parasitic plantsUnderstorey Iayer- consists of shorter trees about 1 m in heightUndergrowth- bamboo thickets and grasses grow densely here during the wet season but are less dense during dry season2TropicaI onsoon Forest CharacteristicsDiversity of plant species- about 200 species in 1 hectare- less species compared to tropical rainforestdue to inconsistent rainfallensity- plant growth is abundant but less dense thantropical rainforest 2TropicaI onsoon Forest Characteristics & AdaptationsLeaves- are deciduous- shed leaves during the dry season to minimiseloss of water through transpiration- waxy with drip tips to allow rainwater to drainoff easily2TropicaI onsoon Forest Characteristics & AdaptationsBark and branches- thick and coarse- protects the trunk from heat and drynessduring the dry season- withstand extreme heat from natural forestfires- branches found around middle of trunks astrees grow less dense than tropical rainforest 2TropicaI onsoon Forest Characteristics & AdaptationsRoots- deep tap roots- to tap water sources deep under theground as rainfall is irregular throughoutthe year0TropicaI forests in a gIance What are the similarities between the tropical rainforest and the tropical monsoon forest? What are the differences?1TropicaI forests in a gIance Similarities- both forests are dense- leaves are waxy with drip-tips2TropicaI forests in a gIance Differencesdiversity diversitydensity densityleaves leavesbark &bark & branches branchesroots roots

AnswersTropical rainforest Differences in terms of Tropical monsoon forestmore diversity lessdenser density less denseevergreen Ieaves deciduousSmooth, thin barkBranches at top one-thirdbark & branchesThick barkBranches around middIe of treeshallow roots deep tap roots

angrove forests Found mainly in areas experiencing tropical climate, along sheltered coastal regions and places where rivers constantly deposit clay and silt.

angrove Forests Structure- grows to a height of 2 m to 0 m- horizontal zones of mangrove species

angrove ForestsCoastaI areaAvicennia and Sonneratia trees are common in this zone, which is the nearest to the coast. They have adaptedto growing in saltwater, as the coastalzone is flooded with seawater during high tide. The trees have breathing roots or aerial roots.iddIe zone#izopora trees are common in thiszone. They have prop roots or stilt roots.InIand zoneBruguiera trees grow further inland, asthey are the least tolerant of salt water. They have knee-like roots.Low tideHigh tide

angrove Forests Characteristics and Adaptations- four main species which are known as halophytes - Avicennia, Sonneratia, #izopora, Bruguiera- dense and luxuriantLeaves- evergreen- salt secretors- ultrafiltrators

angrove Forests Characteristics and AdaptationsFIowers - generally colourful to attract insects to pollinateFruits- buoyant so that waves and currents can carry them away- elongated with sharp tips to anchor in soft muddy soil

angrove Forests Characteristics and AdaptationsRoots- aerial roots that are exposed- allow them to take in oxygen- prop roots- anchor the trees firmly in the muddy soil0Coniferous Forests Coniferous forest- found in places that experience a coolcontinental climate- experiences seasons- temperatures range from -0HC to 21HC - low amount of precipitation, usually in the formof snow, 00 mm tomm in a year- located in Alaska, northern Canada, northernUSA, northern Scandinavia and Russia1 DistributionConiferous Forests2Coniferous Forest Structure- no distinct layers- generally uniform in height, about 20 mto 0 m- trees grow close together- little undergrowth

Coniferous forests Characteristics and Adaptationsiversity-few species as not many trees can adapt to the climate-the trees grow in pure standsensity-forest are not dense as the climate does not support dense vegetation growth

Coniferous Forest CharacteristicsLeaves- evergreen- retain leaves so that photosynthesis can takeplace whenever temperature rises above HC - needle-like with small surface area to reducewater loss due to transpiration- store water for use in winter

Coniferous Forest Characteristics and AdaptationsFIowers and Fruits- trees bear female and male cones- female cones produce seeds- male cones produce pollen- cones can be dispersed by wind oranimals after pollination

Coniferous forest Characteristics and AdaptationsBark and branches- thick bark - to protect from long, cold winters- flexible branches that slope downwards - to enable snow to slide off easilyRoots- shallow, spreading roots- enable trees to absorb water easily from soilsurface when snow melts

Importance of Forests Support diversity of plants and animals. Natural habitats for animals. Provide us with resources. Home to some natives. Part of our natural heritage.

Learning Outcomes GIobaI distribution of tropicaI rainforests,GIobaI distribution of tropicaI rainforests, tropicaI tropicaI tropicaI monsoon forests, mangroves andmonsoon forests, mangroves and coniferous forests. coniferous forests. Characteristics and adaptations of tropicaICharacteristics and adaptations of tropicaI rainforests, tropicaI monsoon forests,rainforests, tropicaI monsoon forests, mangroves and coniferous forests. mangroves and coniferous forests. SkiIIs SkiIIs- - Compare and contrast the characteristics Compare and contrast the characteristicsof different forests. of different forests.