Ecosystems

An ecosystem is a natural system with a group of organisms of plants and animals interacting with the physical environment.

Abtotic components are the non-living features of an ecosystem such as a climate (rainfall and temperature), light, rocks, water and soil.

Biotic components are the living features of an ecosystem, such as animals and plants.

• Soil stores water and nutrients which plants use.
• The soil is home to insects and decomposers.
• Photosynthesis is esstential for ecosystems, for the plants to survive and provide energy (food alternative) and shelter for animals.
• The temperature of the water will affect the survival of coral.
• Pond waste/muck contains non-living particles such as mold and decomposing plant material that serves as food for bacteria and fungi.

Without the imput of the sun, the producers will not be able to grow and photosynthesise. Therefore it affects the consumers as they will not be able to survive and this affects humans because we eat plants and animals.

All plants and animals depend on nutrients in food for their health and vitality. Nutrients occur naturally in the environment and are constantly recycled in every ecosystem.

• Many parts of a plants aren't eaten by an animal, carnivores don't eat all of their prey (such as bones).
• Much of what the animals eat is excreted.
• Energy is last at each level as hunters use a lot of kinetic energy: chasing prey can be time consuming and exhausting. Some herbivores search around for plants to eat.
• Energy is constantly used up for respiration.
• Much of the animal's daily calorie intake is used to stay alive rather than to build a new biomass.

The decomposers are organisms that over time, break down dead organic matter and animal ecretions. They include a mixture of: scavengers (such as insects that eat dead wood) and detritivores (such as bacteria). Decomposers help to return nutrients to the soil in form of an organic substance called humus.

• Located east of London.
• Epping Forest is all that remains of a larger forest that colonised England at the end of the last Ice Age.
• Bogs and ponds in the forest have their own unique species, including 20 kinds of dragonfly.
• For 1,000 years, Epping Forest has been managed in a variety of ways: as hunting grounds for royalty, a timber resource and nowadays, recreation.

• The area has a large number of native trees such as oak, elm, ash and beech.
• It has a great diversity of 177 producer species  of moss, bramble, holly, hazel and field layer of grass.
• There is a variety of insects, mammels and bird consumer species. Including 38 species and 9 amphibians and reptiles.
• Studies have also found 700 species of fungi which is important for decomposing waste.

• The biomass store is large because of the great height of the trees and the dense undergrowth beneath them.
• The soil store is large too because there is always plenty of humus.
• The high flow between the litter, soil and biomass stores reflect vigorous cycle of new growth that takes place each year. The forest loses alot of nutrient each year, via leaching, during episodes of heavy rainfall.

The trees are deciduous (loses leaves) as they are adapted to the UK's seasonal climate, winters are darker and cooler than summers (18 degrees celsius in July and 5 degrees celsius in January [mean monthly temperatures]). As a result the trees grow more broader leaves in the spring and summer; this allows them to maxmise photosynthesis in the summer so they can store more energy during the winter. 

By mid-autumn the forest floor is covered with thick decaying leaves. But, by spring the leaves disappear by the decomposers. Nutrients stored in the leaves is converted to humus in the soil, ready to support the new season's plant growth. This includes the fruits and berries that supports the primary consumers. In the past, coppicing (cutting back trees to encourage new growth of wood) was comman. Today, visitors pick berries and flowers. This helps spread seed which sticks to their clothes.

Periods of extreme weather and climate change, for example 1967-1977 drought in England that killed many trees and 15 millions trees fell by a great storm in 1987.

As a result, population numbers declined for many consumer species in the food chain. Secondary forest growth has since taken place but consumers have migrated back. The recent recovery of English Woodland is an example of ecosystem resilience.

However, ecosystems are sometimes permanently, especially if human forces are invovled. For example, deforestation. The removal of the forest exposes the soil which washes away through rainfall which makes it impossible to recover.

In tropical rainforest regions, where there is heavy rainfall on most days.

In the long term, human induced climate change could threaten the ecosystem balance in many places. For example, changes in temperature and for ecosystems like Epping Forest in their current form.

In some places, grasses (rather than trees) may dominate in the future, if the climate change predictions are correct.

• Tropical forests are found near the equator in Central and South America, parts of Africa and Asia. They are hot and humid and contain a huge variety of plants and animals - around half of all the world's species. The trees are mostly hardwood. The climate is called equatorial.
• Savannah or tropical grasslands are hot and dry, dominated by grass, scrub and occasional trees. They have two distinct seasons - a dry season when much of the vegetation dies back, and a rainy season when it grows rapidly. They are found in central Africa (Kenya, Zambia, Tanzania), northern Australia and central South America (Venezuela and Brazil).
• Desert is the driest and hottest of areas. The world's largest desert is the Sahara in North Africa. Areas of scrub land that border the desert are called desert scrub.
• Mediterranean climates are not too hot or cold. They are found around the Mediterranean Sea, near Cape Town in South Africa and Melbourne in Australia.

• Temperate grasslands are dominated by grass and trees and large bushes are scarce. They have a temperate continental climate - the weather is mild with moderate rainfall. Grasslands include the Puszta in Hungary, the Veldt in South Africa, the Pampas in Argentina and the Prairies in the USA.
• Temperate deciduous forests contain trees that lose their leaves and are found across Europe and USA. The weather is mild and wet. The climate is called temperate maritime.
• Coniferous forests, containing evergreen trees, are found in Scandinavia, Russia and Canada. They have a cool climate with moderate rainfall called cool temperate.
• Mountain areas can be very cold at night and during winter. The growing season is short and at higher levels trees will not grow.
• Tundra surrounds the North and South poles. They have an extremely cold climate, with limited numbers of plants and animals able to survive there.

• Located at the Arctic and Antarctica.
• Cold air sinks at the north and south poles, resulting in very low temperatures and dry conditions.
• The main polar regions are Antarctica and Greenland where temperatures can fall below -50 degrees celsius.

• Located between 15-30 degrees north and south of the Equator.
• The tropical climate in these lowe latitudes is characterised by distinct wet and dry seasons.
• The dry season can be hot and wild fires can break out.
• Violent thunder storms can occur during the wet season.
• Large herds of animals graze on these grasslands, along with predators such as lions and leopards. 

• Located close to the Equator.
• The tropical rainforest recieves high temperatures and heavy rainfall associated with the equatorial low pressure belt, creating the ideal conditions for plants to grow (the sun rays are concentrated at this latitude therefore heating moist air which rises and leads to heavy rainfall).
• Rainforest cover 6% of the Earth's land surface.
• More than half of the world species of plants and animals live in this global ecosystem. 
• A quarter of all medicines come from rainforest plants.

• Located roughly 30 degrees north and south of the Equator close to the tropics of Cancer and Capricorn.
• The air that rises over the Equator heads polewards after shedding its moisture as rain.
• Deserts cover on fifth of the world's land surface.
• Sinking air stops clouds from forming, resulting in high day time temperatures, low night time temperatures and low rainfall.
• Plants and animals have to be well adapted to survive in these conditions.
• The sun's rays are stil highly concentrated at this low latitude. Combined with the dry air, this brings arid desert conditions to places like the Sahara and Australia.

• Found 60 degrees north where winter temperatures are extremely cold due to isolation of sunlight.
• This is due to the earth's tilt when there is no sunlight for several months.
• Coniferous trees have evolved needle leaves that reduce moisture and heat loss during the dark cold months.
• They are also known as evergreens as they retain their leaves to maxmise photosynthesis during the brief summer months.

• These grow in many places at 40-60 degrees North and South of the equator.
• The temperature remains on average 0 degrees celsius even in the winter.
• Rainfall is high (500-1,500 mm per year) as storms arrive regularly due to jet streams, and the east coasts of Asia, North America and New Zealand. 
• The sun rays are weaker at this latitude as a result of these conditions deciduous trees shed their leaves in winter to retain moisture.

• Located 30 and 45 degrees north and south of the equator but only on the west coasts of continents.
• Also located in isolated locations south of the Equator such as South Africa and Western Australia.
• Countries around the Mediterranean enjoy hot, sunny and dry summers with mild winters.
• This is due to the pressure belts migrating slightly north and south during the year.
• Olive, fruit, lemon trees such as lemon and oranges grow here.
• California (USA) and South Africa have similar climate.

• Located 40-60 degrees North and South of the Equator, but only in the centre of continents away from the sea.
• Hot summers but cold winters.
• Quite low rainfall (10-35 inches of precipitation on average per year)
• Mainly grassland vegetation as grassland can tolerate these conditions.
• This land is mainly used for grazing animals.
• Vast areas of glassland in North America (prairies) and Europe (steppes).

• Very dry, cold glassland that is found in every continents except Australia and Antarctica.
• It is mostly found in the USA, Mongolia, Siberia, Tibet and China. There isn't much humidity in the air because Steppe is located away from the ocean and close to mountain barriers.

Although latitude and distance from the sea are the main factors affecting distribution, the following are also important:

• Altitude: temperatures fall by about half a degree for every 100-metre increase in altitude, and tough grasses replace trees on steep mountainsides.
• Mountain ranges: in the USA and Asia, inland areas isolated from the sea suffer from low rainfall. This is because winds blowing off the oceans quickly lose their moisture when air is forced to rise upwards over a high mountain range. The drier lands found east of the USA's Rocky Mountains are said to be in a rain shadow.
• Ocean currents: a cold ocean current flowing along South America's coast helps to create arid conditions in Chile's Atacama Desert because there is little evaporation takes place over the cold water. In contrast, the warm Gulf Stream ocean current affects the climate of western Europe.