People And The Biosphere Flashcards
What is a biome?
Large scale ecosystems with distinctive vegetation
Tropical forests
Hot all year round .20-28 degrees
Because they are found near the equator the day length is around 12 hours meaning the forest gets plenty of sunlight each year
Rainfall is very high around 2000mm each year
Plants are mostly evergreen to take advantage of the continual growing season
Plants grow quickly and shed all year round . These decompose quickly giving the soil a good supply of nutrients
Temperate forests
Have 4 distinct seasons
Rainfall is high up to 1500 mm each year
Sunshine varies throughout the year
The mild and wet climate supports fewer plant species . Trees drop leaves in autumn . These leaves decompose quickly in the moist mild climate allowing the soil to he relatively thick and rich with nutrients
Boreal forests
Have short summers and long winters . In winter the temperature is around -20 degrees and in summer it is around 10 degrees
Precipitation is low less than 500 mm each year.
Plants are evergreen so that they can grow when there is small amounts of light.
There are less animal species in the boreal forest as they must be able to withstand extremely cold temperatures .
Soil has little nutrients as the cold temperatures slow down the decomposition of dead animals and plants
Grassland
Tropical grassland has quite low rainfall (800-900mm each year). Temperatures are highest just before the wet season at 35 degrees and are lowest just after at 15 degrees.
Tropical grasslands have hot summers up to 40 degrees and cold winters down to -40 degrees. They receive little rainfall around 250-500mm each year.
In both of these Grasslands the rainfall is too low to sustain many plant species which affects the animals and soil that lives there .
When the grass decomposes in the tropical grasslands it does provide lots of nutrients for the soil however these nutrients are soon washed out by the wet season.
Temperate grasslands have very few trees however due to high temperatures and little rainfall the soil is rich with nutrients
Deserts
Rainfall is very low , less than 250mm each year. Temperatures can reach 45 degrees during the day and 0 degrees at night.
Plants grow sparsely due to a lack of rainfall
Very few animal species can live in the desert due to the high temperatures
The soil lacks nutrients as the sparse vegetation means leaf litter is small and the dry climate means that organic matter is slow to decompose
Tundra
Temperatures are low around 5-10 degrees in the summer and around -30 in the winter.
Precipitation is less than 250 mm each year and most of it falls as snow
Tundra is found at high latitudes so it gets near continuous day light in the summer and little or no day light at winter.
Plants are lacking as the cold climate stunts growth.
The cold climate and lack of vegetation reduces the animals that love there
The sparse vegetation produces low leaf litter and the cold dry climate slows the rate of decomposition meaning that the soil is nutrient poor.
Factors that affect biome distribution
Altitude-higher altitudes are colder so fewer plants grow which limits the species of animals that live there meaning the soil is very thin.
Rock type-some rocks are easily weathered allowing soil to form. Different rock types contain different nutrients which effects the health of the soil.
Soil type -nutrient rich soil will increase vegetation which allows for more animals to lige there. The acidity of the soil will also determine what plants can grow.
Drainage- if drainage is poor soil gets waterlogged meaning plants adapted to wet conditions can live there.
Biosphere provides lots of resources
Food-many people get their food directly from plants and animals. Other foods grow for profit such as livestock,crops.
Medicine-many plants have medicinal properties and are used to cure illness . Plants in tropical forests have been used to create over 7000 drugs
Building materials-Trees and other plants are often used as building materials . Saps from trees can be used for glues or to make buildings water proof
Fuel-many people rely on plants and animals for fuel. Wood can be burnt for fires . Animal fat can be used as fuel for oil lamps
Exploiting the biosphere
Energy-demand has increased. Large areas of forest are cut down to clear land for biofuel crops. Many tropical forests have been flooded due to HEP dams. Drilling for oil and gas in the tundra has damaged the biosphere as the permafrost is melting .
Water-Demand has increased, Water sources can be over exploited causing damage to the biosphere as animals and plants will not have enough for themselves
Minerals- gold and Iron is used in building and electrical appliances.
These are extracted via mining . This can cause deforestation . Open pit mining causes lots of habitats to be destroyed .
Role of biosphere
Helps to control the proportions of different gases in atmosphere:
Plants take in CO2 and give out oxygen during photosynthesis
Animals take in oxygen and release CO2 when respiring.
This is important as organisms need oxygen to survive
Increased carbon dioxide causes global warming and causes oceans to become more acidic
The biosphere is important in maintaining soil health:
Plant roots and animals spread nutrients through the soil to help maintain soil fertility allowing for more plants to grow, the roots also hold the soil together , the vegetation intercepts lots of the rainfall preventing the nutrients from being washed away
The biosphere regulates the water cycle :
Plants take up water so less of it goes to rivers preventing floods
Plants regulate the global water cycle by storing water and releasing it slowly
Factors increasing the demand for resources
Wealth-economic development means more people are getting richer. Wealthier people have a larger disposable income .
They can afford to spend more money on food and buy more than they actually need
They can buy more electrical appliances using more energy.
Urbanisation-cities are resource intensive compared to rural areas that use little energy.
Food and water must be transported large distances to meet the demand and waste must be removed increasing energy use
Industrialisation-manufacturing goods uses lots of energy. It also uses lots of water to cool down machinary
Malthus’s theory
He believed that the population was increasing faster than the supply of resources and eventually there would be too many people to cater for.
He believed when this happened people would be killed in catastrophes such as conflict , famine and illness . These events would restore the population back down to a level that could be supported
Boserup’s theory
She believed that no matter the size of the population , people would always provide the sufficient amount of resources to meet the needs .
She thought that if supplies were limited people would come up with new technologies to increase production
