Section B : The Living World

Ecosystems Biomes Hot deserts Desertification Development in Hot Deserts Section B : The Living World Tropical rainforests Deforestation Sustainable management of the Amazon Section B : The Living World 1. Ecosystems 1.1. Definitions 1.1.1. Ecosystem - a biological community of interacting organisms and their physical environment. 1.1.2. Biome - an area classified according to the species that live in that location. 1.1.3. Producer - organisms that produce food for themselves and other organisms. 1.1.4. Consumer - organisms that feed on plants or other animals for energy. 1.1.5. Food chain - group of organisms linked in order of the food they eat, from producers to consumers, and from prey, predators, scavengers, and decomposers. 1.1.6. Biodiversity - the variety of organisms found in a particular habitat. 1.1.7. Nutrients - chemical substances found in every living thing on Earth. 1.1.8. Decomposition - the breakdown of animals and plant structures by bacteria and the release of carbon compounds into the atmosphere, soil and to the ocean floor. 1.2. Ecosystem is made up of living + non-living things 1.2.1. biotic - living things (plants, animals) 1.2.2. abiotic - non-living things (air, sunlight, water, rocks) 1.3. Interdependence in ecosystems 1.3.1. All the biotic parts of an ecosystem depend on eachother and the abiotic parts in order to survive. 1.3.1.1. example:small pond ecosystem 1.3.1.1.1. In this example the Kingfisher (a bird) depends on: -Fish for food -Trees for a nesting place and shelter -The pond itself for water 1.3.1.1.2. In return, the kingfisher helps the ecosystem by: -Spreading seeds of the trees and other plants -Eating some fish, so they don’t over-run the pond -Giving the soil nutrients when they defecate! 1.4. Nutrient Cycling 1.4.1. Nutrients are elements that plants and animals need for growth and survival. This includes nitrogen, carbon, phosphorous and several other elements. 1.4.2. In this diagram of a simple ecosystem, we can see how nutrients are passed round the ecosystem. Plants take in nutrients from the soil, through their roots. Animals then absorb these nutrients when they eat the plants. When plants and animals die, they decompose. This releases those nutrients back into the soil. The nutrients can be taken in again by a different plant. This is often called nature’s recycling system! 1.4.3. example : pond ecosystem 1.5. Food Chain 1.5.1. how it works? 1.5.1.1. - Food chains show us how nutrients are passed through an ecosystem. - The arrows in a food chain diagram show which way the nutrients are moving. - So, this means that arrows will always point towards the animal that is eating! 1.5.1.2. Food chain - one flow of energy and nutrients through the ecosystem. 1.5.2. the different levels 1.5.2.1. producer -> primary consumer -> secondary consumer -> tertiary consumer -> decomposers (back to producer) 1.5.3. 1. start 1.5.3.1. - Plants take in nutrients from the soil through their roots. - Combined with water, carbon dioxide and sunlight, plants make their own energy for growth. - Because green plants make their own energy, they are called producers. - Producers are the start of every food chain and provide nutrients to be passed around the ecosystem 1.5.4. 2. passing on nutrients 1.5.4.1. - Producers make their own energy, and are nearly always green plants. - The nutrients and energy are then passed on when something eats the producer. The thing that eats the producer is called the primary consumer - a rabbit, in this example. - Whatever eats the primary consumer is called a secondary consumer. As you go up the food chain, you get tertiary consumers and even quaternary consumers. - Each time nutrients are passed along the chain, some energy is lost to movement, excretion and other animal activities. 1.5.5. 3. end 1.5.5.1. - All plants and animals in a food chain will die at some point. - Dead bodies of all organisms are broken down by decomposers in the soil. - Decomposers include things like bacteria, earthworms and even some fungi (mushrooms!). - When the bodies of organisms are broken down, the nutrients held in them are returned to the soil, where they originally came from. - This process is called decomposition. - As the nutrients return to the soil, they can be absorbed again by a brand new producer. 1.6. Food Web 1.6.1. how it works? 1.6.1.1. Food web - all the flows of energy and nutrients through the ecosystem. 1.6.1.2. In most ecosystems there will be different producers and consumers, and quite a range of animals that eat each other. To show all the flows of energy and nutrients in an ecosystem, we use a food web. A food web shows every possible food chain in one ecosystem 1.7. Changes that can affect ecosystems 1.7.1. Climate – the temperature or rainfall could increase or decrease New species – the introduction of new plants or animals provides competition Disease – this could kill off one or more species in the ecosystem. Plants or animals. Humans – we cause pollution and destroy ecosystems, but we also try to conserve some 1.7.2. examples 1.7.2.1. Global warming 1.7.2.1.1. This is a semi-desert ecosystem where grow has caused less plant growth If the producers here are not growing as much, there will be less food for the primary consumer 1.7.2.2. Deforestation 1.7.2.2.1. Deforestation removes producers from the food web, which severely interrupts the nutrient cycle. But it also means that there is less shelter for animal species. 1.7.2.3. Introduction of new species 1.7.2.3.1. Red squirrels used to be really common in Angland But the grey squirl was introduced after 1945 It is bigger therefore eays more The competition for food made red squirrels disapear from most of england 2. Biomes 2.1. Different biomes 2.1.1. Oceans Wetlands Temperate forests Tropical rainforests Mountains Grasslands Deserts Polar region 2.2. How is a biome classified? 2.2.1. climate 2.2.1.1. Hot, temperate, or cold Wet, maritime(wet climate) or dry Lots of sunlight, or often cloudy 2.2.2. soils 2.2.2.1. Dry or sandy or moist Rich in nutrients or poor 2.2.3. plants and animals 2.2.3.1. High or low biodiversity? Abundant life or not 2.3. Biomes of the world 2.3.1. desert 2.3.1.1. - Location : 20-35 north and south of equator - Climate : extreme heat in day, up to 50 degrees celsius. Cold at night. Very dry! - Plants and animals : Not much plant life, some such as cacti. Not many animals, but snakes, lizards and some larger. - Soils: Extremely dry and sandy. Not many nutrients. 2.3.2. tropical rainforests 2.3.2.1. - Location: lie along the equator and can be found in South America, Africa, South-east Asia and Australia - Climate: here the sun's rays are concentrated--> high temperatures, moist air - Plants and animals: ideal conditions for plants growth, home to more than 50% of all animal and plant species (6% of the lands surface is rainforests) - Soils: infertile, thin, poor nutrients 2.3.3. temperate deciduous forests 2.3.3.1. - Location: 50-60 degrees north of the Equator, north america, western europe Climate: seasons based on temp (cold winter, warm summer), rainfall all year - Plants and animals: high biodiversity (lots of species), deciduous trees (lose their leaves) - Soils: fertile, nurient-ruch soils 2.3.4. tropical grasslands (savanna) 2.3.4.1. - Location: between 15 and 30 degrees north and south of the equator - between tropical rainforests and hot deserts. - Climate: distinct wet and dry seasons due to the Hadley cell - the dry season is longer and can be extremely hot with wildfires common, whereas the wet season can see torrential downpours and intense thunderstorms. - Plants and animals: few trees and are home to large grazing animals such as giraffes, elephants and zebras, along with predators such as lions and cheetahs. 2.3.5. temperate grasslands 2.3.5.1. - Location: around 40 degrees north and south of the Equator - Climate: inland so they experience hot summers and cold winters (as they don't benefit from the seasonal warming and cooling effects from the sea). - Plants and animals: This biome is dominated by short tussock and feather grasses and the land is mainly used for grazing. 2.3.6. mediterranean 2.3.6.1. - Location: lies around 40 degrees north and south of the equator, in southern Europe, California (USA), South Africa and Western Australia - Climate: hot and dry summers and mild winters. - Plants + Animals: Vegetation includes small drought resistant trees and evergreen shrubs, as well as olive trees and citrus trees (such as oranges and lemons) 2.3.7. coniferous forests 2.3.7.1. - Location: roughly 60 degrees north of the Equator, in places such as Scandinavia, Canada, and northern Russia. - Climate: Winter is bitterly cold in this biome - because of the earth's tilt there is very little sunlight for several months. - Plants + Animals: Coniferous trees have needles instead of leaves which retain heat and moisture during the cold dark winters, they are also evergreen meaning that they can maximise photosynthesis during the short summers. 2.3.8. tundra 2.3.8.1. - Location:60-70 degrees north to the Arctic Circle, in Northern Europe and Canada Climate: very cold, windy and dry conditions (below freezing for most of the year) due to the angle of solar radiation, meaning the sun's rays are spread out over a large area. The land is frozen for much of the year, and when it is not frozen the surface ice thawing leads to waterlogging - Plants + Animals: Plants and animals are well adapted to survive the cold, for example, plants are low growing to withstand the wind and retain heat and moisture. - Soils: The tundra is fragile and threatened by oil and mineral exploitation and tourism. 2.3.9. polar 2.3.9.1. - Location: within the Arctic and Antarctic circles - Climate: cold air sinks here so the temperatures are extremely low (can drop to -50°C) and there is very little precipitation, making the poles officially deserts. The main polar regions are Antarctica and -Greenland, where the land is permanently frozen. - Plants + Animals: There are very few plants and animals in this biome as conditions are so harsh. 3. Tropical rainforests 3.1. Location 3.1.1. - Tropical rainforests are found along the equator. - They are distributed between the Tropics of Cancer and Capricorn. - The biggest rainforest is in South America but there are also large rainforests in Central Africa and South East Asia. 3.1.2. why are rainforests located at the equator? 3.1.2.1. Temperature: High levels of solar radiation between tropics, leads to warm climate all year round 3.1.2.2. Rainfall: Hot air rising at the equator (as part of the Hadley Cell) creates heavy clouds and very high rainfall 3.2. Climate 3.2.1. Rainfall is lowest over the summer months, and highest over late winter and spring Rainfall is highest December – may, (over 270 mm average rainfall over these months), rainiest month is march. Temperature doesn’t fluctuate, stays the same Warm temperature all year round ( between 25-27). Why are rainforests so hot + wet? - High levels of solar radiation between tropics, leads to warm climate all year round, hot air rising at the equator (as part of the Hadley Cell) creates heavy clouds and very high rainfall 3.3. Structure of a tropical rainforest 3.3.1. highest -> lowest 3.3.2. emergent 3.3.2.1. - 1 or 2 of the tallest trees - Around 50 metres. - Large buttress roots, widespread to stop them falling down in the wind - e.g. Kapok Trees - Very windy in emergent layer. 3.3.3. canopy 3.3.3.1. - 20-30 metres - Shades lower layers - Tall + straight trees, few branches 3.3.4. under-storey/under-canopy 3.3.4.1. - 10-20 metres - Young trees, growing quickly to reach sunlight - Insects, sloths howler monkeys - Lianas – hanging vines 3.3.5. shrub layer 3.3.5.1. - 0-10 metres - Small plants + flowers, e.g. orchids - Large animals, e.g. jaguar, anaconda, elephants 3.3.6. forest floor 3.3.6.1. - Very Dark - About 5% of light reaching - A lot of dead/decaying plant matter -> decomposition happens quickly - Shallow and infertile soil 3.4. Adaptations (to environmental characteristics) 3.4.1. definition 3.4.1.1. Adaptation – is any trait that helps an organism, such as plant or animal, survive and reproduce in its environment. 3.4.1.2. 1. Extreme rainfall 3.4.1.2.1. Drip Tip Leaf 3.4.1.2.1.1. - Shape of leaf makes water run quickly off the surface - Waxy surface will help drip tip 3.4.1.2.2. Animals adapted to live and hunt in water 3.4.1.2.2.1. Jaguars are great swimmers and can hunt fish, caymans and anacondas 3.4.1.3. 2. Competition for sunlight and nutrients 3.4.1.3.1. Big Butress roots 3.4.1.3.1.1. - Anchor the tallest trees and stabilise them in the wind - They spread wide but are shallow to gather as much water and nutrients as possible from the poor soils 3.4.1.3.2. Plants have wide leaves with big surface areas 3.4.1.3.2.1. - Catch as much sunlight as possible - Particularly in the under-canopy layer 3.4.1.3.3. Trees trunks: 3.4.1.3.3.1. - Very straight - No branches because only focused on growing upwards towards the sunlight in the canopy 3.4.1.4. 3. High biodiversity 3.4.1.4.1. - Colourful plants – to attract insects to pollinate them. - Animals adapted to eat a unique diet – e.g. toucans have razor sharp beaks to crack open nut/fruit shells that only they can eat (reduces competition for food) 3.4.1.5. 4. Adaption to layers 3.4.1.5.1. Spider monkeys – adapted to live in canopy layer, away from predators. Incredibly strong tails that allow them to swing between the trees + thrive 3.4.1.5.2. Geckos – special adapted pads on their feet that allow them to 'stick' to smooth tree trunks and be able to climb them to safety. 4. Deforestation 4.1. Causes 4.1.1. 1. Farming in the rainforest 4.1.1.1. Large areas cleared for pastoral (animal) farming Global demand for meat has increased --> many cattle farms have opened in the Amazon Basin for beed farming Arable (plants) farming also responsible for the loss of tropical rainforest as many farmer are clearing land to grow crops, such as soya beans Cleared rainforest -> flat grassy area (good for farming) 4.1.2. 2. Logging 4.1.2.1. Tropical rainforests are cut down so that valuable trees like mahogany can be accessed and sold for timber to make furniture Trees cut down to make paper products 4.1.3. 3. Road Building 4.1.3.1. Construction of access roads for farmers, loggers and miners 4.1.4. 4. Energy Development 4.1.4.1. HEP (hydro electric power) Creation of HEP stations in the Amazon rainforest has resulted in large areas of forest being flooded to create the reservoirs and dams Flooding of Balbina dam in Brazil resulted in the loss of 920 square miles of tropical rainforest 4.1.5. 5. Population growth / new settlements 4.1.5.1. Population growth has resulted in the loss of tropical rainforest as land is cleared to build houses and infrastructure 4.1.6. 6. Mineral extraction (mining) 4.1.6.1. The amazon basin is rich in natural resources such as iron ore ,copper, tin, aluminum, manganese and gold Led to development of mines Results in clearance of tropical rainforest The Carajás mine in Brazil is the World's Largest iron ore mine. 4.2. Consequences 4.3. Case Study : The Amazon Rainforest 4.3.1. location 4.3.1.1. equator goes straight through it 4.3.1.2. The majority of the forest, 60%, is in Brazil, followed by Peru with 13%, Colombia with 10%, and with minor amounts in Bolivia, Ecuador, French Guiana, Guyana, Suriname, and Venezuela. 4.3.2. deforestation rate 4.3.2.1. 2004-2012 – Big decrease in deforestation, by about 80%. 4.3.2.2. 2012 -2020, slow but steady increase, nearly doubling 4.3.2.3. 2018-2022, President Bolsonaro encouraged more deforestation 4.3.2.4. More than 25% of the rainforest is now gone. One football pitch every minute. 4.3.3. causes of deforestation 4.3.3.1. Cattle Ranching: - provides beef for export is responsible for 80% of deforestation TNCs like McDonalds - Growing soya beans to feed the cattle 4.3.3.2. Mining: - for gold - biggest mine in the world for mineral extraction is Carajás in Brazil 4.3.3.3. Energy Development - Hydroelectric Power (HEP) - Balbina Dam flooded over 900 square miles of rainforest 4.3.3.4. Subsistence farming - local farmers 'slash and burn' rainforest to clear space to farm for themselves and their families - subsistence, enough for you, your family + a little income 4.3.4. impacts 4.3.4.1. negative 4.3.4.1.1. Nearly 1/3 of global CO2 emissions are linked to deforestation --> climate change 4.3.4.1.2. Removing trees means less CO2 absorbed + Burning trees =CO2 released 4.3.4.1.3. Loss of nutrients in the nutrient cycle --> Producers are removed, soils lose nutrients 4.3.4.1.4. Removal of trees = soils is exposed and will erode permanently 4.3.4.1.5. Habitat loss as canopy layer is completely wiped out 4.3.4.2. positive 4.3.4.2.1. Improves transportation -> through forest means easier access to raw materials like minerals and timber (Trans Amazonian Highway -> important for exports and trade) 4.3.4.2.2. Important economic gain from: -mahogany -beef -gold 4.3.4.2.3. Significant number of jobs in mining and energy industries 4.3.5. importance to people + the planet 4.3.5.1. Amazon absorbs around 20% of CO2 that humans emit 4.3.5.2. 3 million people live in the Amazon, many in tribal communities (importance on local scale) 4.3.5.3. More than 75% of medicines (e.g. cancer drugs) are found in the amazon (importance on global scale) 4.3.5.4. 20% of the world's oxygen comes from the Amazon. 5. Sustainable management of the Amazon 5.1. Sustainable management techniques: 5.1.1. ECOTOURISM - Small scale tourism. Little groups allowed to visit ecolodges and resorts that do not damage the rainforest 5.1.1.1. economic benefit 5.1.1.1.1. - Tourism brings money into the local economy - Jobs provided in eco-lodges and as tour guides around the rainforest - Jobs in tourism often pay better than agriculture 5.1.1.2. environmental protection 5.1.1.2.1. - Small lodges and eco-friendly and do not destroy rainforest - Tourists can also engage in conservation projects - Also helps raise awareness across the world 5.1.1.3. example : Cuyabueno Reserve (wildlife reserve) 5.1.1.3.1. Small lodges using local materials (use fallen trees) Tour guides for locals Very small groups of tourists (5/6 people) 5.1.1.3.2. What are the sustainable features of this resort ---> 5.1.1.3.2.1. - Haven't cut down trees to make space, huts built between trees use local materials - Small 5.1.2. SELECTIVE LOGGING - Cutting down a % of trees in an area, but not all. Sometimes replanting is also used in the same place. 5.1.2.1. economic benefit 5.1.2.1.1. - Trees can still be harvested for their valuable wood, e.g. mahogany - Income and jobs provided for local people 5.1.2.2. environmental protection 5.1.2.2.1. - Some trees remain, so nutrient cycle and water cycle are not interrupted Habitats and food for organisms remain - Biodiversity is not reduced. 5.1.2.3. example : Brazil Nuts in Peru 5.1.2.3.1. - Brazil nut trees are incredibly valuable - Brazil nut harvest generates a lot of income for people and the country - Use of selective logging of 1-2 trees per hectare, does not affect the Brazil nut harvest. 5.1.3. CONSERVATION + EDUCATION – Small projects aimed at conserving habitats, while providing education to the wider world 5.1.3.1. economic benefit 5.1.3.1.1. Conservation groups often team up with big businesses to help them use the rainforest sustainable 5.1.3.2. environmental protection 5.1.3.2.1. - Schemes help to protect endangered species - No deforestation at all allowed in conservation zones - Raising awareness of rainforest issues encourages more people to act to protect them 5.1.3.3. example : The Great Projects in Peru 5.1.3.3.1. - Internships for students centered on conservation projects. - Monitor and record butterfly species to help protect their habitat - Workshops to improve the knowledge of their interns. 5.1.4. INTERNATION ARGREEMENTS – Countries around the world signing agreements to reduce illegal deforestation for hardwoods. 5.1.4.1. economic benefit 5.1.4.1.1. - Valuable hardwoods can still be traded, allowing for businesses in the country Illegal activity is reduced, so less need to spend money fighting it 5.1.4.2. environmental protection 5.1.4.3. examples: 5.1.4.3.1. The Mercosur Agreement 5.1.4.3.1.1. - E.U. put pressure on South American countries (e.g Brazil) to reduce deforestation - They used a trade deal to negotiate and force less deforestation 5.1.4.3.2. COP26 5.1.4.3.2.1. At COP26 meeting in 2021 all countries agreed to use £14 billion to protect rainforests from illegal deforestation. 5.1.5. DEBT REDUCTION - lots of countries use economic gain from deforestation to repay their debts to richer countries (e.g Peru and USA). Lenders can reduce the debt level in exchange for forest conservation. 5.1.5.1. economic benefit 5.1.5.1.1. Developing countries have less debt to pay off Money can be spent developing alternative industries for employment 5.1.5.2. environmental protection 5.1.5.2.1. Very large areas of rainforest can be protected in this way It encourages more sustainable economic activity in rainforests, like ecotourism. 6. Development in Hot Deserts 6.1. general 6.1.1. opportunities 6.1.1.1. tourism 6.1.1.1.1. Camel rides 6.1.1.1.2. Quad-biking + sand-boarding 6.1.1.1.3. Jeep rides on dunes 6.1.1.1.4. Bedouin camp visits + cultural experience 6.1.1.1.5. Hot air balloon ride (to see landscape) 6.1.1.1.6. Unique landscape 6.1.1.2. energy generation 6.1.1.2.1. Solar energy (deserts have a lot of sunlight) 6.1.1.2.2. Wind farms 6.1.1.3. agriculture 6.1.1.3.1. Pistachios 6.1.1.3.2. Date palms (Morrocco) 6.1.1.3.3. Watermelons 6.1.1.4. mineral extraction 6.1.1.4.1. Oil (Arabian desert) 6.1.1.4.2. Precious metals + stones 6.1.1.4.3. Sand 6.1.2. challenges 6.1.2.1. lack of water 6.1.2.1.1. Any settlements need clean water sources 6.1.2.1.2. <250mm of rain per year 6.1.2.1.3. Makes irrigation difficult 6.1.2.1.4. Infertile soil 6.1.2.2. inaccessible 6.1.2.2.1. hard to build infrastructure 6.1.2.2.2. difficult to get resources to any settlements 6.1.2.3. extreme weather 6.1.2.3.1. death valley -- >40 degrees 6.1.2.3.2. heat related illness are a danger 6.2. CASE STUDY : MOJAVE DESERT, USA 6.2.1. Opportunities 6.2.1.1. Farming 6.2.1.1.1. Long hours of sunshine – perfect for crop growth 6.2.1.1.2. Irrigation, aquifers and canals have enabled large-scale commercial agriculture 6.2.1.1.3. 80% of colorado's water used for farming 6.2.1.2. Tourism 6.2.1.2.1. National parks, e.g. Grand Canyon 6.2.1.2.2. Colorado Museum (cultural centre – native american histroy centre) 6.2.1.2.3. Las vegas – 37million tourists anually (home to around 2 million people) 6.2.1.3. Energy Development 6.2.1.3.1. World's largest solar farm - Ivanpah 6.2.1.3.2. Alta Wind Energy Centre (mojave wind farm) (exposed to wind, due to being baron) 6.2.1.3.3. Hoover Dam on the Colorado River 6.2.1.3.4. Many fossil fuels 6.2.1.4. Mineral extraction 6.2.1.4.1. Valuable minerals – copper + uranium (uraniam used in nuclear power plants) 6.2.1.4.2. Opencast mining – large-scale 6.2.1.4.3. However ..(Conflict with other activities such as farming and tourism, so not land is fully exploited) 6.2.2. Challenges 6.2.2.1. water insecurity 6.2.2.1.1. Lack of rainfall 6.2.2.1.2. Threatened by climate change 6.2.2.1.3. Have to find ways to supply water to settlements/agriculture etc… 6.2.2.2. inaccessibility 6.2.2.2.1. Lack of investment into roads – risk of breaking down 6.2.2.2.2. Road network varies across the desert 6.2.2.2.3. Tourism means transport infrastructure is good around Las Vegas 6.2.2.3. extreme climate 6.2.2.3.1. Harsh conditions e.g. 50 degrees c in summer 6.2.2.3.2. Indigenous people have settled near rivers or aquifers 6.2.2.3.3. Adaptations: homes built to keep cool during the day + warm at night, light paint to reflect solar radiation, gardens have 'desert landscaping', e.g. artificial grass 7. Desertification 7.1. definition 7.1.1. Desertification - Process of land becoming a desert. / Fertile land turning into desert. 7.2. water cycle process 7.2.1. Plants absorb water from rainfall and return water to the atmosphere through transpiration, leading to more rainfall. Their roots help to stabilize/hold soil together and protect it from erosion 7.2.2. what would happen if you removed the plants? 7.2.2.1. No transpiration + local water cycle 7.2.2.2. No roots to hold the soil together --> soil erosion 7.2.2.3. Rain falling onto bare ground 7.2.2.4. Less water held in the soil --> soil is drier 7.3. causes of desertification 7.3.1. main causes 7.3.1.1. Animals over grazing Deforestation Urbanisation 7.3.2. 1st Firewood needed for homes 7.3.2.1. 2nd People cut down trees to obtain firewood 7.3.2.1.1. ---> Removal of vegetation ---> soil erosion, loss fertility ---> desertification 7.3.3. 1st Livestock needed for farming and food 7.3.3.1. 2nd Livestock graze over lots of land and consume and trample vegetation 7.3.3.1.1. ---> Removal of vegetation ---> soil erosion, loss fertility ---> desertification 7.3.4. 1st Too much crop growth causes over-use of soil and loss of nutrients 7.3.4.1. 2nd Natural vegetation can no longer grow in poor soils 7.3.4.1.1. ---> Removal of vegetation ---> soil erosion, loss fertility ---> desertification 7.3.5. 1st Population Growth 7.3.5.1. 2nd Need more land for crops and more firewood 7.3.5.1.1. ---> Removal of vegetation ---> soil erosion, loss fertility ---> desertification 7.3.6. 1st climate change causes long periods of drought 7.3.6.1. 2nd Plants in the area die due to lack of rainfall 7.3.6.1.1. ---> Removal of vegetation ---> soil erosion, loss fertility ---> desertification 7.3.7. 1st cause 7.3.7.1. 2nd step 7.3.7.1.1. ending steps 7.4. Where is desertification a risk? 7.4.1. Areas surrounding existing deserts, because it is spreading outwards 7.5. Region at risk : Darfur in Sudan (sahel region) 7.5.1. Environment under pressure before 2003 7.5.2. One year out of every 5 brings drought, crop failure and livestock loss to Sudan 7.5.3. In Sudan and neighbouring countries, food production has not kept pace with the growing population 7.5.4. 2003, nomadic cattle herders and settled farmers began to fight over water supplies and land. Herders were deliberately prevented from reaching water sources by farmers, which led to overgrazing. 7.5.5. Once the vegetation was gone, their cattle died. In revenge, some herders chased farmers from their villages, and cut down their crops and trees. 7.5.6. Population growth ---> overgrazing 7.5.7. Population has times by 5 between 1973 and 2003 7.5.8. Getting even higher due to people migrating to Darfur 7.6. Solutions to Deforestation 7.6.1. 1. Afforestation 7.6.1.1. Large scale tree planting Adds nutrients to soil Roots stabilise soil + avoid erosion Stimulates water cycle with transpiration 7.6.1.2. e.g The Great Green Wall in the Sahel : 11 countries, plant to plant trees coast to coast 7.6.1.3. positives 7.6.1.3.1. Will protect land for 300million people 7.6.1.3.2. World Bank is donating $2bn in funding 7.6.1.3.3. It has created completely green areas for rural communities in Senegal 7.6.1.4. negatives 7.6.1.4.1. It takes decades to grow, lots of farming communioties cut down the new trees for fuel 7.6.1.4.2. Many countries have weak or unstable governments who do not put the plan into practice. 7.6.2. 2. Soil + water managment 7.6.2.1. Bunds = earth barriers, Stone lines 7.6.2.1.1. These structures keep rainfall in puddles and prevent surface and soil erosion 7.6.2.1.2. This allows plant growth 7.6.2.1.3. Low cost, doesn’t require additional resources or skills. 7.6.2.1.4. Appropriate technology (because they have low infrastructure, poorest region in the world – sub-Saharan Africa) 7.6.2.2. Drip irrigation 7.6.2.2.1. Only allows small amounts of water to individual plants 7.6.2.2.2. Hugely reduces water use/loss and maximises effectiveness 7.6.3. 3. Appropriate Technology 7.6.3.1. Efficient stoves 7.6.3.1.1. New stoves are more efficient and require less fuel, so fewer trees are cut down 7.6.3.2. e.g. Ripple Africa (also and example of charitable aid) 7.6.3.2.1. Donate stoves to families in parts of Africa 7.6.3.2.2. Already donated 125,000 7.6.3.2.3. 250,000 bundles of wood saved each week 7.6.3.2.4. Over half a million people have benefitted so far 7.6.3.2.5. Quick, cheap + easy to build 8. Hot deserts 8.1. Location (distribution of hot deserts) 8.1.1. - 30 degrees north and south of the equator - Almost no deserts along the equator - The largest area of hot deserts is the Sahara (the biggest continuous desert in the world) - Australia is mainly desert - Most countries in the middle east have significant deserts 8.2. Climate 8.2.1. Dry, Barron, Hot, Low biodiversity Windy, Sandy, Arid (dry, geographical term), Low rainfall (less than 250mm a year) 8.2.2. Very cold at night in winter (can get below freezing) Very dry, sandy soils – low in nutrients Very low biodiversity Between 15-20 different species 8.2.3. Temperature: 8.2.3.1. Near to equator, so high solar radiation Very few clouds means higher temperatures because no radiation is blocked 8.2.3.2. In the winter, the temperature in hot deserts is around 15 degrees In the summer, for 4 months the temperature is around 30 degrees 8.2.4. Rainfall: 8.2.4.1. Air is descending around 30 degrees north + south of the equator, so no clouds can form. Therefore, very little rainfall. Under 250mm of rainfall a year. 8.2.4.2. All year rainfall is incredibly, is always less than 7mm per month In the 4 summer months of the year there is no rain at all Less than 250mm per year 8.3. Living in the desert 8.3.1. Subsistence living – where you produce enough for you and your family, self-sufficient Nomadic lifestyle – always moving around (due to lack of resources and plants to eat, your animals to eat) 8.4. Adaptations ( plants + animals ) 8.4.1. Invertebrates (dung bettles, scorpions) 8.4.1.1. e.g. scorpions don't drink water but instead absorbs water from the animals it eats, they also slow down it's respiration and intake of oxygen – body processes slow down and so can survive on only 2 bugs a year 8.4.1.2. Need less energy so don't need to eat as much. 8.4.2. Camels 8.4.2.1. Camels have long eyelashes, long legs, wide feet, and a hump to store fat 8.4.2.2. - Long eyelashes help to protect the eyes from sand, - the hump that stores fat sustains a longer duration of energy for the camel as there is a lack of food in the desert. - Wide feet help the camel to walk on the walk and not sink, long legs bring body further away from very hot sand. 8.4.3. Leaves - waxy skin 8.4.3.1. Waxy skin - some leaves have a thick, waxy skin on their surface. 8.4.3.2. This reduces water loss by transpiration 8.4.4. plants - water storage 8.4.4.1. Water storage - some plants, known as succulents, store water in their stems, leaves, roots or even fruits. Plants which store water in their leaves and stems also have a thick waxy skin. 8.4.4.2. They lose less water by transpiration 8.4.5. small leaves 8.4.5.1. these ensure that less water is lost from the plant by transpiration because the leaf has a smaller surface area. 8.4.6. tap roots 8.4.6.1. Tap roots - these are long roots (7-10 metres long) 8.4.6.2. Reach deep under the ground to access water supplies. The tap roots are much longer and bigger than the plant which is visible at the surface. 8.4.7. fennec foxes 8.4.7.1. Fennec foxes are protected from the scorching heat of the sand by having thick fur on their paws. 8.4.7.2. Their light fur offers them protection through camouflage, as well as reflecting sunlight to keep them cool. Their massive ears allow heat loss by providing a large area of exposed skin full of blood vessels. 8.5. adaption 8.6. how it helps survival in the hot desert