HASS Biomes + Food Security: PART ONE: BIOMES AND TROPICAL RAINFORESTS

Define biome

a major ecological community of plants and animals adapted to a particular climate and occupying a large area

Define abiotic

these are non-living factors that affect living organisms such as soil, topography or weather

Define biotic

these are living factors (such as plants, animals, humans, fungi and bacteria) and the actions or effects of living things (eg diseases, competition, predation)

Define climate

the average weather conditions over a very large area of the Earth's surface and over a long period of time.

Define arid

a dry climate, lacking in rainfall

Define convectional rainfall

rain caused by hot moist air that rises into the atmosphere, cools, condenses and forms clouds and rain. Common in tropical areas.

Define deciduous

broadleaf trees / shrubs that shed their leaves in winter each year

Define desertification

process of becoming desert: a process by which land becomes increasingly dry until almost no vegetation grows on it, making it a desert

Define ecosystem

an ecological system formed by the interactions of all living organisms with each other and with the environment in which they live

Define evergreen

a plant that has green leaves throughout the year

Define horizon (in terms of soil)

a layer of soil (eg most soils have an organic rich A horizon, or top soil)

Define humus

the organic component of soil, (brown or black in colour) formed by the decomposition of leaves and other plant material by soil microorganisms

Define leaching

the process in which water runs through the soil, dissolving nutrients and minerals and carrying them into the subsoil

Define precipitation

the forms in which moisture is returned to the Earth from the sky, most commonly in the form of rain, hail and snow

Define rain shadow

the dry area on the leeward side of a mountain range

Define salinity

Measurement of the quantity of salts found in a soil. Many semi-arid and arid areas are naturally salty. Salinity can be caused by over-irrigation or clearing of vegetation.

Define solar insolation

the energy coming from the sun (incoming solar radiation)

Define weathering

the chemical or mechanical processes by which rocks exposed to the weather undergo changes in character and break down into particles (soil)

Define xerophytic

adaptations that allow a plant to cope with dry / drought conditions (eg the ability to store large amounts of water like a cactus)

List the nine main biomes

Tropical rainforest, tropical savanna, desert, woodland, temperate grassland, temperate deciduous forest, boreal forest (taiga), tundra, polar ice cap

Describe the location and distribution of tropical rainforests

- Located around the equator, between 0°-10°

- Located in northern South America, mid-Africa and the middle east, in countries such as Democratic Republic of the Congo, Indonesia and Brazil

Examples of tropical rainforests

Amazon in South America, Congo Basin in Africa

Describe the climate in a tropical rainforest

Hot and humid with heavy rainfall

Describe the soil of a tropical rainforest

- Very deep, up to 20m deep due to the rapid breakdown of parent rock (rapid chemical weathering occurs in warm and moist conditions

- Low in nutrients due to leaching rainwater

Describe the vegetation of a tropical rainforest

- Has lush, dense, evergreen vegetation

- Has great biodiversity - over half the world's plant and animal species live there

- is multi-storeyed, meaning the tallest trees are the emergents, underneath is the canopy, underneath that is the under canopy, underneath that is the shrub layer and then the forest floor with the buttress roots

Describe buttress roots

Tall canopy trees that have roots that grow outwards for stability. shallow roots to absorb soil nutrients close to the surface

Describe drip tips

The tip of a leaf points down. this enables rain to run off quickly to shed water to avoid the growth of fungus and bacteria on the leaf

Describe epiphytes

plants that grow on the trunks and leaves of other trees. They do this to get closer to the sunlight to photosynthesise

Describe the tall trunks adaptation

Trees grow tall trunks with wide, umbrella shaped canopies above the canopy. This is to get maximum sunlight

examples of the four adaptations of tropical rainforest vegetation

Buttresses: rubber tree, fig tree, kapok tree

Drip Tips: fig tree, papaya tree

Epiphyte: bromeliads, orchis

Tall trunks: kapok tree, brazil nut tree