Topic 7: People & The Biosphere Flashcards
What are biomes?
Large-scale, global ecosystems with distinctive vegetation
Why do different parts of the world have different biomes?
The climate in an area determines what type of biome forms. So different parts of the world have different biomes as they have different climates
Name 3 biomes
- Tropical forest
- Temperate forest
- Boreal forest
Climate of Tropical forests
- Same all year round, no definite seasons
- Hot (temperatures 20-28 degrees) due to being near the equator
- Day lengths are the same all year round (12hrs) due to being near the equator, so recieves plenty sunshine all year
- High rainfall (2000mm per year), rains everyday
Characteristics of Tropical forests
Plants - most trees are evergeen to take advantage of the continual growing season. Plants grow quickly & are adapted to take in maximum light
Animals - the dense vegetation provides lots of food & different habitats, so there are lots of different species of animal (gorillas, jaguars, etc). Lots of species of insects and birds
Soil - plants grow quickly & shed leaves all year round. These decompose quickly, so theres constant supply of nutrients in soil that are cycled quickly
Climate of Temperate forests
- 4 distinct seasons. The summers are warm & winters are cold
- High rainfall (1500mm per year), all year round
- Shorter days in winter, longer in summer. Hours of sunshine vary through the year
Characteristics of Temperate forests
Plants - the mild, wet climate supports fewer plant species than tropical forests, but more than boreal forests. Forests made up of broad-leaved trees that drop leaves in autumn, shrubs & undergrowth
Animals provides food & habitats for mammals (eg. foxes, squirrels), birds and insects
Soil - plants lose their leaves in autumn, leaf litter decomposes quickly in moist, mild climate. Meaning soils are relatively thick & nutrient-rich
Climate of Boreal forest
- Short summers & long winters. Average temperature in winter is below -20 degrees, and 10 degrees in summer
- Low Precipitation (less than 500mm per year), mostly falls as snow
- Lots of daylight during summer, but little to none during winter. Clear skies so plenty of sunshine in daytime
Characteristics of Boreal forest
Plants - most trees evergreen, so can grow whenever theres enough light. Coniferous trees (pine & fir) are common, as are low-growing mosses & lichen
Animals - relatively few animal species (eg. black bears, wolves, eagles) compared to tropical forests because less food available & animals need to be adapted to the cold climate to survive.
Soil - cool, dry climate means needles from trees decompose slowly, so soils are quite thin, nutrient-poor and acidic. In some areas, ground is frozen most of year
What are the 2 types of Grassland
- Tropical grassland
- Temperate grassland
Climate in Tropical grasslands
- Quite low rainfall (800-900mm per year)
- Distinct wet and dry seasons
- Temperatures are highest (35 degrees) before wet season & lowest (15 degrees) just after it
- Found near equator, so recieve lots of sunshine all year round
Characteristics of Tropical grasslands
Plants - consists mostly of grass, scrub & small plants, with few scattered trees
Animals - home to lots of insects (grasshoppers, beetles), larger animals include (lions, elephants)
Soil - grass dies back during dry season forming a thin, nutrient-rich soil, but nutrients are washed out of soil during wet season
Climate of Temperate grasslands
- Hot summers (up to 40 degrees) & cold winters (-40 degrees)
- Lower rainfall than tropical grasslands (250-500mm per year)
- As further from equator, the amount of light recieved varies throughout year
Characteristics of Temperate grasslands
Plants - Much like tropical grassland, dominated by grasses & small plants, very few trees
Animals - home to fewer animal species than tropical grasslands, mammals (bison, wild horses), rodents (mole rats)
Soil - high temperatures in summer means that decomposition is fast, so soils are relatively thick & nutrient-rich
Climate of Deserts
- Very low rainfall (less than 250mm per year). Might only rain once every 2-3 years
- High temperatures range from 45 degrees at day and 0 degrees at night
- Recieve more dayligt during the summer than winter. Little cloud cover, so lots of sunshine everyday
Characteristics of Deserts
Plants - plant growth is sparse due to lack of rainfall. A few plants such as cacti, thornbushes grow
Animals - relatively few animal species. Those that do are adapted to cope with the harsh climate (eg. lizards, snakes, etc)
Soil - the sparse vegetation/plant growth means there is little leaf litter, & the dry climate means that organic matter is slow to decompose. As a result, soils are mostly thing & nutrient-poor
Climate of Tundra
- Low temperatures (5-10 degrees in summer and -30 degrees in winter)
- Very low precipitation (less than 250mm per year). Most of this falls as snow
- Found at high altitudes so gets near-continuous daylight in the summer & little to no daylight in winter.
Characteristics of Tundra
Plants - cold climate & lack of light in winter makes it hard for plants to grow. Hardly any trees. Vegetation includes mosses, grasses, low shrubs
Animals - cold climate & lack of vegetation means relatively few animal species can survive. Those that do include arctic hares, arctic foxes, etc. Some animals migrate south for the winter
Soil - the spares vegetation produces little leaf litter, & the cold, dry climate means organic matter decomposes slowly, so soil is thin & nutrient-poor. There is a layer of permafrost (permanently frozen ground) below soil surface, which stops water draining away
What factors affect biome distribution?
Alititude - higher altitudes are colder, so fewer plants grow there, which limits animal species. Meaning theres not much organic matter so soils are thin
Rock type - some rocks are easily weathered to form soils & different rock types contain different minerals, affecting how nutrient-rich the soil is. Some are permeable, others are impermeable
Soil type more nutrient-rich soils can support more plants. The acidity & drainage of soils also varies, affecting the plants that can grow
Drainage - if drainage is poor, soil gets waterlogged & only plants adapted to wet conditions can grow
What are biotic components?
Living components of a biome (eg. plants, animals)
What are abiotic components?
Non-living components of a biome (eg. soil, water, rock)
What is the biosphere?
Includes all parts of the Earth that are occupied by living organisms
What does the biosphere offer to people?
Food - many indigenous people get all their food directly from plants & animals. Picking wild fruit, veg & nuts, hunting & trapping animals
Medicine - lots of plants have medicinal properties & are used to cure illnesses & keep people healthy. Plant species in Tropical forests have been used to create over 7000 drugs
Building materials - trees & other plants often used as building materials. Sap from trees can be used as glue or to make buildings waterproof, reeds & straw used for roofs & plant fibres for rope
Fuel - indigenous people rely on plants & animals for fuel to cook & for warmth. Wood, moss, dried grass & dried animal dung is burnt for fuel
How do humans exploit the biosphere?
Energy - demand for energy is increasing as global population increases. Forests are cut down to clear land for growing crops that can be used to make biofuels, or to make way for coal mines or power stations
Water - demand for water is also increasing due to increases in global population - people use water for washing, irrigating farmland, etc. Water sources are over-exploited, leaving plants/animals with lack of water to survive
Minerals - minerals such as gold & iron are increasing in demand for a variety of uses. They are extracted from mines found in tropical forests that are responsible deforestation, release of toxic chemicals, etc.
