Not unlike ecosystems, natural biomes also consist of distinctive plant/animal species which have adapted to their surrounding environment
While ecosystems vary in size, biomes are very large areas with similar characteristics and are usually classified according to the dominant vegetation found within a particular region
Biomes can be classified as either terrestrial (land based) or aquatic(water based)
There are many different classifications for the world’s natural biomes
Most natural biomes though are influenced/modified by human activity
Major biomes
Forest and woodland
Grassland
Desert
Tundra
Alpine
Forest and woodland biomes
Dominated by trees
Forests have very tall trees that are spaced relatively close together forming a closed canopy
Woodlands have smaller trees that are separated by some distance so there is an open canopy
The height and spacing of trees in a biome is generally influenced by the amount of rainfall received by the region
Tropical Forests
Distributed in areas of the world near equator and between tropic of cancer and tropic of Capricorn
Characterised by very hot temperatures and high average annual rainfall
Regions which receive heavy rainfall all year round, with no distinct dry season are referred to as tropical rainforests
Regions which receive seasonal rainfall, influenced by changing monsoon winds, are referred too as monsoon forests
One of most distinctive feature of tropical forests is multi-storey arrangement
Each layer has own particular characteristics which has adapted to both the climate and microclimate within the forest
Some taller trees emerge above canopy as they compete for sunlight
Smaller plants such as epiphytes and orchids also grow on branches of the tall trees to gain access to light, while others climb up the trees like vines to reach the light
Beneath canopy is understory
Nearer to the forest floor plants are usually quite sparce
Forest floor is also covered with the litter of leaves and branches which decompose relatively quickly due to the warm, moist conditions
Temperate forests
2 types: warm and cool
Warm temperate forest biome occurs in mid-latitude regions experiencing hot summers, cool to mild withers and moist conditions all year round
Warm temperate forest plants have adapted into broad leafed evergreen trees in response to the plentiful and evenly distributed rainfall
Cool temperate forest biomes occur mainly in the mid to high latitude regions of the northern hemisphere
These regions have high rainfall with very cold winters
Taiga forests
Aka boreal/coniferous forest
Occurs between 50 and 60 degrees latitude in the northern hemisphere
Summers moderately warm and wet with around 400-1000 mm of precipitation per year
Winters long, cold and dry
Soils are thin, nutrient poor and acidic
Woodlands
Open canopy woodlands have evolved in parts of the world characterised by moderate and often seasonal rainfall
Savanna woodlands are found in tropical regions characterised by hot, wet summers and warm, dry winters
Mediterranean woodlands are found in regions between 30 and 40 degrees north/south of the equator, characterised by warm-hot dry summers and cool-mild wet winters
Plants are generally adapted to periods of seasonal drought
Developed waxy, leathery leaves to reduce water loss through transpiration and have thick, rough barks to insulate themselves against the heat and protect them from fires
Some species have wide spreading roots to gather as much water as possible when rain falls, while others have thick, strong tap roots which enable the to penetrate through the rock and access the water table
Grasslands
Found in moderately drier parts of world
2 main divisions of grasslands include savanna grasslands and temperate grasslands
Savanna Grasslands
Always found in climates with relatively hot, wet summers and warm, dry winters where the annual rainfall ranges from about 500-100 mm per year
Different savannas support different grasses depending o n the amount of rainfall received and soil conditions
The soil of the savanna grasslands is porous with rapid drainage of water
Temperate grasslands
Characterised by hot summers and cold winters with moderate seasonal rainfall
Amount of rainfall received influences height of grassland vegetation, with taller grasses in wetter regions and short grasses in drier regions
Soil of temperate grasslands is deep and dark, with fertile upper layers
Deserts
Desert biomes have very dry, arid climates
Usually characterised as receiving less than 250 mm of rainfall per year
Hot deserts are found around the tropics while cold deserts are found in higher latitudes
While daytime deserts are very high, night temperatures are relatively low
Vegetation tends to be stunted and widely spaced, having adapted to both limited moisture and poorly developed soils
Drought evaders are only short lived with life cycles of approximately 2-6 weeks
Drought escapers are plants that are able to find alternative water supplies to rainfall
Drought resisters are plants which have adapted by reducing the amount of water lost through transpiration
Water conservers are plants which store water to use during very dry periods
Tundra
Found in very cold regions of northern hemisphere from artic circle to north pole
Bound to the south by coniferous forests of taiga
Extremely low temperatures, little precipitation, poor nutrients, and short growing seasons are all factors which have contributed to this treeless landscape
Soil is formed slowly and consists of a layer of permanently frozen sub soil called permafrost
No deep root systems in vegetation of arctic tundra
However there is still a wide variety of plants that have adapted to the cold climate
All of the plants are adapted to strong winds, group together to resist the cold temperatures and can carry out photosynthesis at low temperatures and low light intensities
Alpine
Located at high altitudes on mountains just below the snowline
Temperatures vary according to latitude, altitude and aspect but in general, are below freezing in the winter and rise to about 10 degrees during the summer, making them too cold to support trees
Plants have adapted to both high altitudes and extreme climates
Protect themselves from cold and wind by growing close to ground
When they die the don’t decompose very quickly because of cold
Makes for thin, sandy and rock soil conditions which tdihe plants have also adapted to
Australia’s biomes
One of the world’s larges countries
Sheer size of land mass which spreads across much of the Earths southern latitude means that there is a wide variety of climates and landscapes that form many biomes across Australia
Many of Australia’s original biomes has been changed by human activities
Resulted in significant changes to vegetation, lad and water across much of the country
2nd driest continent in the world, after Antarctica
Also describe Australia as arid/semi-arid as 70% of continent receives less than 500 mm of rainfall per year
Low rainfall results in large desert areas
Some desert arias in Australia have large areas of red dunes but some are covered in vast areas of stones, called gibber plants
In most of Australia’s desert areas, grasses and low shrubs dominate the landscape
More than 135000 farms in Australia
Can be classified in many different ways, e.g. growing crops, raising livestock, how large it is
Farms that require large areas of land fall under classification of extensive farming
Farms such as poultry farms, or those that grow vegetables, can produce large volumes of food/fibre in small area, classified as intensive farming
Farming in northern Australia is determined by environmental factors, particularly temerature, soil fertiliser and water
Soils in north are among the worlds oldest and have been subject to monsoonal downpours for millions of years
Much of the soils are arid/semi-arid and rain that does fall tends to be seasonal rather than all year round
Makes intensive farming difficult
Several government task forces have identified the water that lies in rock layers(aka aquifers) beneath northern Australia as the key to expanding intensive agriculture