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Geography Tropical rainforest models Tropical Rain Forest Geography Geography Rain Forest Family Forever United Streaming 13:28 Tropical Rain Forest Geography -found near the equator -temperature varies little from approximately 23°C -the length of daylight varies from 12 hours by less than one hour -rainforest>2000mm Geography How many species are lost from tropical forests annually? Over 20,000 How big is the Amazon Rainforest? Half the size of the USA Geography Rainforests are home to over 50% of the world’s species Brazil has the world’s largest total tropical rain forest acreage Many acres are cleared to raise cattle. There is now 50% less rain forests that 50 years ago. Geography Effects of Deforestation • http://app.discoveryeducation.com/playe r/?assetGuid=EA2E9E17-F6CD-4D449481AD80F4AFD7A3&fromMyDe=0&isPrint erFriendly=0&provider=&isLessonFrom Health=0&productcode=US&isAssigned =false&includeHeader=YES&homework Guid= Tropical Rain Forest -canopy trees up to 55 m tall Geography -soils are generally unfertile -largest biome, on an area basis -nutrients and carbon stored in plant biomass, not soils Tropical Savanna/Seasonal Forest Geography Tropical Savanna/Seasonal Forest Geography -found in the tropics (but > 10° latitude) -pronounced dry season with <5 cm rainfall in some months Temperate Forest Geography Temperate Forest Geography -distinct winter season, frost a defining feature -summer season usually moist with ppt > evapotranspiration Temperate Forest -relatively large tree biomass -also called the deciduous forest, but contains evergreen needle trees as well Geography Geography Rainforest plants And the enormous the number of different species of plants grow in rainforests, with many species occurring only in one particular region. Unlike other forests, rain forests have an abundance of : Epiphytes plants which live above the ground growing on tree trunks and branches, Example orchids, ferns, mosses Climbing plants including large woody climbers called lianas which are rooted in the soil and usually reach the canopy. The climbers twist around the tree trunks, and loop from one tree to another in the canopy, binding the trees together. Strong scent of fruits attracts animals, which feed on the fruit and assist in dispersal of the seeds Thick, waxy surface of leaves protects against hot sun, heavy rain, and strong winds Aerial roots of epiphytes absorb moisture from the air Geography Strong scent and bright colours of flowers attract insects which assist in pollination Tall straight trunks no side branches Thin, smooth bark Shallow spreading root system Buttress roots Geography Pitcher plant - a carnivorous plant. Parasitic plant slippery rim tendril Orchid - sun-loving roots attached themselves to branches and absorb nutrients Insects falling into the pitcher are digested, and nutrients which are released are absorbed by the plant. Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools Structure of the rainforest Geography The dominant plants in a rainforest are giant trees. The hot wet climate enables them to grow all year round, and they remain evergreen, continuously shedding their leaves and growing new ones. The average height of rainforest trees is about 45 metres, although the emergence (trees which tower above the others) may go as high as 90 metres. Smaller trees growing the under story (layer between the canopy and the forest floor). Several layers can be identified within the forest 45 Geography A Emergent 40 tree canopy 35 30 25 B Large trees of Middle layer 20 15 C Lower tree layer 10 D Shrub/small tree layer 5 Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools E Ground vegetation Canopy layer - formed by the crowns of the tall trees andGeography contains a mass of branches, Leaves, flowers and fruit. Conditions in the canopy vary, and include: •Hot sunshine •Heavy rainfall •Tropical storms Middle layer - the Vegetation here is more sparse. The trees tend to have pointed crowns and, when a giant tree falls, they grow quickly to fill a gap in the canopy Conditions within the forest on more or less constant: •There is little variation in temperature •The air is moist and still •Rain on the canopy drips to the forest floor several minutes later •A breeze is rare, even during storms Geography Shrub layer - scattered shrubs, saplings (young trees) and ferns. Herb layer - a few non-woody, soft stemmed plants with thin leaves. Leaf litter - thin layer covers the forest floor. Soil layer - most roots growing the top 10 centimetres whether nutrients are found.