Ecosystems
- An ecosystem includes all the biotic and abiotic parts in an area, and it is the interdependence of climate, soil, water, plants and animals
- A food chain shows what eats what and a food web shows lots of food chains and how they overlap
- The organisms can be classed as producers, consumers or decomposers
- A producer is an organism that uses sunlight energy to produce food
- A consumer is an organism that gets its energy by eating other organisms
- A decomposer is an organism that gets its energy by breaking down dead matter, returning nutrients in the soil to be used by plants
- Bacteria and fungi are decomposers
- Within every ecosystem there are stores and flows of nutrients, water and energy
Global Ecosystems
- Polar regions are found around the north and south poles
- This is the Arctic and Antarctica
- Polar areas are very cold with temperatures usually less than 10°C
- Winters are normally below -40°C and can reach almost -90°C
- Precipitation is low – no more than 500mm in the year, mainly in the summer
- There are clearly defined summers and winters which are even colder
- There are few florae
- Some lichens and mosses are found on rocks, and there are a few grasses and flowering plants on the coast where its warmer
- Plants grow slowly and don’t grow very tall – grasses are the most common plants
- Closer to the poles, only mosses and lichen can survive
- Some small, short trees and shrubs grow in warmer, sheltered areas
- They grow close to the ground because it is too windy
- They grow slowly because soil lacks nutrients
- They have small leaves and lose little moisture
- There are relatively few different species of faunae
- Polar bears, penguins and marine mammals like whales, seals, and walruses are examples of animals found there
- Coral reefs are mostly found between 30° north and south of the equator, a few miles off the coast
- For example, the Great Barrier Reef, Australia
- Coral reefs are most common in warm areas that receive a lot of sunlight
- They grow best in shallow, clear, salty water
- Coral reefs form underwater, so few florae grow there
- Tiny algae live inside the tissue of corals
- The algae and coral depend on each other for nutrients
- Coral itself is a fauna – it’s a bit like a sea anemone, but some species create a hard-outer coating for protection
- Around 25% of all marine species live in coral reefs, including fish, molluscs, sea snakes, turtles and shrimps
- Many fish have flat bodies so they can easily swim through and hide in small gaps in the coral
- There are two types of grasslands
- Tropical savannah grasslands are found between the tropics
- For example, the African Savanna in central Africa (Kenya and Tanzania)
- There are distinct wet and dry seasons
- They have quite low rainfall at 800-900mm a year
- Temperatures are highest, around 35°C, just before the wet season
- Temperatures are lowest, around 15°C, just after the wet season
- They are home to grass, scrub and small florae with a few scattered trees
- Plants are adapted to cope with low levels of rainfall with long roots and small waxy leaves
- They are home to lots of insects and fewer large faunae
- There are many species of grasshoppers, beetles and termites
- There are lions, elephants, giraffes, zebras and antelope
- Grazing animals, such as antelope, travel long distances in search of food and water, while other animals, such as mole rats, dig burrows to escape the harsh climate
- Temperate grasslands are found at mid-latitudes
- For example, the veldts of Africa and the pampas of South America
- There are hot summers and cold winters
- Temperatures reach 40°C and -40°C
- They receive 250-500mm of precipitation each year, mostly in late spring and early summer
- They are home to grasses and small florae, with very few trees
- Grasses have wide-spread roots
- There are fewer fauna species than savannah grasslands
- Mammals include bison and wild horses, and rodents
- Grazing animals, such as antelope, travel long distances in search of food and water, while other animals, such as mole rats, dig burrows to escape the harsh climate
- Temperate forests are found mainly in the mid-latitudes, between the tropics and the polar regions
- For example, the Valdivian forest on the south-western coast of South America (Chile and Argentina)
- There are four distinct seasons
- The summers are warm, and the winters are cool
- Rainfall is very high, up to 1500mm a year, with rain all year round
- Temperate forests are full of trees, florae type depends on the type of forest
- Deciduous forests have broad-leaved trees that drop their leaves in autumn, shrubs and undergrowth
- These include oak trees, brambles and ferns
- Forest-floor plants, such as bluebells, tend to flower in spring before the trees grow leaves and block out light
- Coniferous forests have evergreen trees and an understory of grasses and low-lying plants
- These include pine and fir trees
- They support lots of different fauna species
- Mammals include foxes and squirrels, birds include woodpeckers and cuckoos and insects include beetles and moths
- Streams and ponds are habitats for insects to breed
- Insects provide food for fish, including trout and salmon
- Tropical forests are found around the equator, between the tropics
- For example, Daintree National Park, Australia
- The climate is consistent all year round, with no definitive seasons
- It’s hot, at around 20-28°C, because the Sun is overhead all year round
- Rainfall is very high, around 2000mm a year
- It rains daily, usually in the afternoon
- There are four layers of florae – emergent layer, canopy, understory and forest floor
- Most trees are evergreened to take advantage of the continual growing season
- Vegetation cover is very dense, so very little light reaches the forest floor
- There are lots of epiphytes such as orchids and ferns
- Emergent trees have buttress roots to support their trunk and only have branches at their crown, where the light can reach
- Plants lower down the canopy have broad leaves in order to absorb as much light as possible
- Rainforests contain more fauna species than any other ecosystem
- Gorillas, jaguars, anacondas, tree frogs and sloths inhabit rainforests
- There are many bird and insect species
- Many animals are camouflaged to hide from predators
- Leaf-tailed geckos look like leaves to hide from predators
- Some animals are nocturnal to save energy by feeding in cooler hours
- Sloths are only active at night
- Hot deserts are found between 15° and 35° north and south of the equator
- For example, the Sahara Desert, northern Africa
- Temperatures are very extreme between day and night
- They range between 40°C during the day to 0°C at night
- There’s less than 250mm of rainfall a year
- The time of rain varies, sometimes only once in a couple of years
- Flora growth is scarce due to the lack of rainfall
- Cacti and thorn bushes grow
- Plant roots are very long to reach deep water supplies, or very wide near the surface to reach as much rainwater as possible
- Some plants have fleshy stems and thick, waxy skin
- Fauna are adapted to cope with the harsh climates
- Lizards, snakes, insects and scorpions are common in desserts as small animals can hide under the sand when it is too hot
- Many birds migrate when it gets too hot
- Many animals are nocturnal and live in burrows during the day
- Larger animals, such as camels, have evolved to tolerate dehydration and reduce water loss
