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People and the Biosphere

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What are biomes?
Large-scale, global ecosystems with distinctive vegetation.
What is an ecosystem?
An ecosystem includes all the living and non-living things in an area.
What does the climate of an area determine?
What type of biome forms. So different parts of the world have different biomes because they have different biomes.
Is the climate in a tropical forest the same all year round?
Yes.
What is the temperature of tropical forests like?
Between 20-28'C. This is because near the equator the Sun is overhead all year round.
Is the day length in tropical forests the same all year round?
Yes (about 12 hours). This is because they are near the equator and get plenty of sunshine all year round.
What is the rainfall like in tropical forests?
It is high (about 2000mm per year).
What are the plants like in tropical forests?
Most trees are evergreen to take advantage of the continual growing season. Plants grow quickly and are adapted to take in maximum light.
What are the animals like in tropical forests?
The dense vegetation provides lots of food and different habitats, so there are lots of different animal species, e.g. gorillas, tree frogs and sloths.
What is the soil like in tropical forests?
Plants grow quickly and shed leaves all year round. These leaves then decompose very quickly and so there is a constant supply of nutrients in the soil, and these nutrients are cycled quickly.
Do temperate forests have distinct seasons?
Yes, 4 distinct seasons. The summers are warm and the winters are cool.
What is the rainfall like in temperate forests?
It is high (up to 1500mm per year) and there is rain all year round.
Do the day lengths vary in temperate forests?
Yes. Days are shorter in winter and longer in summer- the hours of sunshine vary though the year.
What are the plants like in temperate forests?
The mild, wet climate fewer plant species than tropical forests, but more than boreal forests. Forests are often made up of broad-leaved trees that drop their leaves in autumn (e.g. oak), shrubs (e.g. brambles) and undergrowth (e.g. ferns).
What are the animals like in temperate forests?
The mild climate and range of plants provides food and habitats for mammals (e.g. foxes), birds (e.g. woodpeckers) and insects (e.g. moths).
What is the soil like in temperate forests?
Plants lose their leaves in autumn, and the leaf litter decomposes quite quickly in the moist, mild climate. This means that soils are relatively thick and nutrient-rich.
What are the summers and winters like in boreal forests?
They have short summers and long winters. In winter average temperatures are below -20'C and can drop much lower. In summer average temperatures are about 10'C.
What are the precipitation levels like in boreal forests?
Precipitation is low- generally less than 500mm per year. A lot of this falls as snow.
How much daylight do boreal forests get?
A lot during summer months, but little or none during the winter. Skies tend to be clear, so during daylight hours there is plenty of sunshine.
What are the plants like in boreal forests?
Most trees are evergreen, so they can grow whenever there is enough light. Coniferous trees such as pine and fir are common, as are low-growing mosses and lichen.
What are animals like in boreal forests?
There are relatively few animal species in boreal forests compared to e.g. tropical forests, because there is less food available and animals need to be adapted to the cold climate to survive. Animals that live there include black bears and elk.
What is the soil like in boreal forests?
The cool, dry climate means that needles from the trees decompose slowly, so soils are quite thin, nutrient-poor and acidic. In some areas the ground is frozen for most of the year.
Describe some features of tropical grasslands:
- Quite low rainfall (800-900 mm per year).
- Distinct wet and dry seasons.
- Temperatures are highest (around 35'C) just before the wet season and lowest (about 15'C) just after it.
- They are found around the equator so they get lots of sunshine all year round.
- They consist mostly of grass, scrub and small plants, with a few scattered trees.
- Home to lots of insects, e.g. grasshoppers and larger animals, e.g. lions.
- Grass dies back during dry season forming a thin, nutrient-rich soil, but nutrients are washed out of the soil during the wet season.
Describe some features of temperate grasslands:
- Hot summers (up to 40'C) and cool winters (down to -40'C).
- 250-500 mm precipitation each year, mostly in late spring and early summer.
- Because they are further from the equator, the amount of light they receive varies through the year.
- They are dominated by grasses and small plants, and have very few trees.
- Home to fewer animal species than tropical grasslands- mammals include bison and wild horses, and rodents such as mole-rats.
- High temperatures in summer mean that decomposition is fast, so soils are relatively thick and nutrient-rich.
What is the rainfall like in deserts?
Less than 250mm per year.
What is the temperature in deserts like?
Hot in the day (e.g. 45'C) to cold at night (below 0'C).
Is there much daylight in the desert?
There is more daylight during summer than winter. Because there is little cloud cover, they get lots of sunshine every day.
Are there many plants in the desert?
No, there are few plants due to the lack of rainfall e.g. cacti.
Are there many animals in the desert?
There are not many and those that do are adapted to cope with the harsh climate. E.g. lizards.
What is the soil like in the desert?
The sparse vegetation means that there is little leaf litter, and the dry climate means that organic matter is slow to decompose. As a result, soils are mostly thin and nutrient-poor.
Describe some features of the Tundra biome:
- Temperatures are low- around 5-10'C during the summer and lower than -30'C in the winter.
- Precipitation is also very low- less than 250mm per year. Most of it falls as snow.
- Tundra is found at high latitudes, so it gets near-continuous daylight in the summer and little or no daylight in the winter. There is more cloud cover in the summer.
What are the plants like in the tundra biome?
The cold climate and lack of light in winter make it hard for plants to grow, and there are hardly any trees. Vegetation includes mosses, grasses and low shrubs.
What are the animals like in the tundra biome?
The cold climate and lack of vegetation means that relatively few animal species live in the tundra. One of those that does is the arctic fox. Some animals migrate south for the winter.
What is the soil like in the tundra biome?
The sparse vegetation produces little leaf litter, and the cold, dry climate means that organic matter decomposes slowly, so soil is thin and nutrient-poor. There is a layer of permafrost below the soil surface, which can stop water from draining away.
How does altitude (local factor) affect biome distribution?
Higher altitudes are colder, so fewer plants grow there, which also limits the number of animal species. This means that there is not much organic matter so soils are thin or non-existent.
How does rock type (local factor) affect biome distribution?
Some rock types are easily weathered to for soils, and different rock types contain different minerals. This affects how nutrient-rich the soil is. Some rocks are also permeable and others are impermeable.
How does soil type (local factor) affect biome distribution?
More nutrient-rich soils can support more plants. The acidity and drainage of soils also varies, affecting the plants that can grow. E.g. peat soils are very acidic, so only acid-tolerant plants such as conifers can grow, and clay soils are sticky, so water can't flow through very easily.
How does drainage (local factor) affect biome distribution?
If the drainage is poor, soil gets waterlogged and only plants adapted to wet conditions can grow there. Very wet areas may become home to aquatic species of plants and animals.
What are biotic components?
Living parts of the biome- e.g. plants and animals.
What are abiotic components?
Non-living parts- e.g. soil, water, rock, atmosphere.
Name some ways biotic and abiotic components of biomes interact:
1) Water availability affects the plants that can grow- e.g. if the soil is very dry only desert plants such as cacti will be able to survive. Plants take in water from the soil and release it into the atmosphere, providing moisture for further rainfall.
2) The type and density of vegetation affects the type of soil that forms, and the type of soil that forms affects the type of vegetation that can grow- e.g. dense vegetation cover and lots of leaf fall means that lots of nutrients will be added to the soil, which can then support more plant growth.
3) Some organisms cause biological weathering. This is when rocks in the ground are broken up into smaller pieces by living things, e.g. tree roots breaking rocks up as they grow.
What are indigenous people?
People who are native to an area.
Name 4 resources the biosphere provides:
1) Food.
2) Medicine.
3) Building materials.
4) Fuels.
How is food obtained by indigenous people?
Many get all of their food directly from pants ad animals. Some forage for food, picking wild fruit, vegetables and nuts, hunting and trapping animals and catching fish. Others grow food for their own use, e.g. growing cereals, fruit and vegetables and raising livestock.
How is medicine used?
Lots of plants have medicinal properties and are used to cure illnesses and keep people healthy. Plant species in tropical forests have been used to create over 7000 drugs.
How does the biosphere provide building materials?
Trees and plants are often used as building materials, e.g. pine from taiga forests is used to make furniture and build houses. Sap from trees can be used to make glue or to make buildings waterproof, reeds and straw can be used for roofs and plant fibres can be used to make rope.
How does the biosphere provide fuel?
Indigenous people rely on plants and animals for fuel and cooking and keeping warm. Wood, moss, dried grass and dried animal dung is burnt as fuel. Some indigenous people in areas with little vegetation (like tundra), use animal fat, e.g. blubber from seas, as fuel for oil lamps.
Why do humans exploit the biosphere?
For commercial gain.
How and why do humans exploit the biosphere for energy?
Demand for energy is increasing as population increases and people have more electronic devices. Large areas of forest are cut down to clear land for the growing of crops that can be used to make biofuels, or to make way for coal mines or power stations. Some areas of tropical forests have been flooded from the building of hydroelectric dams. Also, drilling for oil and gas in the tundra is damaging because pipelines are melting the permafrost.
How and why do humans exploit the biosphere for water?
Population increase has caused demand for water to increase. Water resources e.g. lakes and aquifers can be over-exploited- this is happening in arid areas like the Sahara desert. This can damage the biosphere, as plants and animals no longer have enough water to survive.
How and why do humans exploit the biosphere for minerals?
Minerals such as gold and iron are used in many things such as electrical appliances and the demand for them is increasing. Minerals are often extracted by mining. Mines in tropical forests are responsible for lots of deforestation and toxic chemicals are washed into streams and rivers, killing wildlife. Open pit mining removes large areas of the land surface.
How does the biosphere help maintain good CO2 levels?
The plants in the biosphere take in CO2 and give out O2 and the animals take in O2 and give out CO2.
Why is maintaining the balance of gases in the atmosphere important?
Because...
1) Most living organisms need O2 to survive.
2) Increased CO2 can lead to global warming.
3) Increased CO2 can make oceans acidic.
4) Some CO2 is needed to keep the Earth warm enough to support life.
How does the biosphere help keep soil healthy?
- Plant roots and animals spread nutrients through the soil- this helps maintain soils structure and fertility, which helps plants to grow.
- The roots of vegetation also hold the soil together so it does not get eroded by wind and rain.
- Vegetation intercepts rainfall before it reaches the ground. This helps to prevent leaching- where nutrients are washed downwards out of reach of the plant.
What is the hydrological (water) cycle?
It is the movement of water between land, bodies of water and the atmosphere.
How is the biosphere an important control on the water cycle?
- Water is taken up by plants, so less reaches rivers. This helps to prevent flooding and soil erosion.
- Plants help to regulate the global water cycle by storing water and releasing it into the atmosphere slowly. Large areas of forest, e.g. the Amazon rainforest, can reduce the risk of drought and flooding in areas a long way away.
The water cycle:
What are population projections?
Predictions of how many people there will be in the world in the future.
What is the highest population prediction the world has been given?
14 billion people.
How is increasing wealth increasing the demand for resources?
1) Economic development means that people are getting wealthier.
2) Wealthier people have more income, which affects their resource consumption:
-They have more money to spend on food and they often buy more than they need.
-The can afford cars and electrical appliances which use energy. Manufacturing these goods and producing the energy to run them uses a lot of water.
-More people can afford flushing toilets, showers etc. This can increase water use.
How is urbanisation increasing the demand for resources?
-Cities tend to be more resource-intensive than rural areas- street lights and neon signs use energy, and fountains and urban parks require water.
-Food and water have to be transported long distances to meet the increased demand in cities, and waste needs to be removed- this increases energy use.
How is industrialisation increasing the demand for resources?
Industrialisation is a shift in a country's main economic activity from primary production to secondary production.
1) Manufacturing cars, electrical appliances, chemicals and other good uses a lot of energy.
2) It is increasing the production of processed goods, e.g. foods such as margarine. This increases demand for ingredients such as palm oil, which are often grown on huge plantations.
What is Mathus's theory?
18th century economist
- He thought that population was increasing faster than the supply of resources, so eventually there would be too many people for the resources available.
- He believed that, when this happened, people would be killed by catastrophes such as famine, illness and war and that the population would return to a level that would be supported by the resources available.
What was Boserup's theory?
20th century economist
- Boserup believed that however big the world's population grew, people would always produce sufficient resources to meet their needs.
- If resource supplies became limited, people would come up with new ways to increase production in order to avoid hardship.
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