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	Ecosystems
	What’s an ecosystem ?
	•Ecosystem is derived from the Greek word oikos, for “house,” eco-is the combining form meaning “environment or habitat.” •Groups of living things and the environment they live in make up an ecosystem. An ecosystem has two parts. Biotic Factors •Living things (plants, animals, bacteria) Abiotic Factors •Non living things (air, water, soil, climate …)

	How does an ecosystem work ?
	Plants use sunlight, water and nutrients from the soil to produce their own food (producers) The animals feed on the plants, or each other (consumer) Fungi and Bacteria feed on dead waste material and make things break down and rot. (decomposers) Without plants, all other living things would die.

	POPULATIONS •A group of the same species living in the same place at the same time is a population. •Populations live in environments to which they are adapted.
	COMMUNITIES •A community of an ecosystem is made up of all the populations that live in the same area. •The plants and animals that live together depend on each other to survive.
	HABITATS •The environment that meets the needs of an organism is called a habitat.
	NICHES •A niche is an organism’s role or job in the environment.
	FOOD CHAIN
	A food chain shows where energy goes in an ecosystem. Food chains start with a plant.

	Food Web
	Food chains link to form food webs. A complete food web for an ecosystem can be large and complex.

	The Recyclers (Decomposers)
	•In the end every living thing in an ecosystem dies and is eaten by the decomposers. •When they make material rot they release the nutrients from it, these sink back into the soil and get used again. Without decomposers soil would quickly run out of nutrients so no plants would grow and ecosystems would collapse.

	What is a biome?
	A biome is a large ecosystem. It is an area on the earth's surface that has similar climate, plants and animals. There are 8 main biomes: Tundra Taiga Temperate forest Tropical rainforest Desert Mediterranean Savanna Temperate grassland

	Climate affects the growth of vegetation in various ways
	Precipitation Particularly the total amount and how it’s distributed through the year. Temperature Especially the seasonal pattern and the length of the growing season. Number of Sunshine Hours Which determines the amount of light for photosynthesis. Rates of evaporation, transpiration, and humidity.

	Tropical Rainforest
	Climate in the Rainforest
	Daily Rhythm. •No real seasons. •8:00 a.m. dry intense heat from the sun. •12:00 noon – high temperatures up to 33ºc, formation of cumulus clouds. •6:00 p.m. thick cumulonimbus clouds, thunderstorms and torrential downpours of rain. Temperature •Average of 28ºc •Occasionally it goes above 35ºc. •Never goes below 20ºc •Temperature range can be as little as 2ºc. Precipitation •Typically 2000 mm per year. •Atmosphere is sticky, hot and humid.

	Climate graph of the Amazon

	Layers of the Rainforest
	•The dominant plants in a rainforest are giant trees. The hot wet climate enables them to grow all year round, and they remain evergreen, continuously shedding their leaves and growing new ones. • •The average height of rainforest trees is about 45 metres, although the emergence (trees which tower above the others) may go as high as 90 metres. Smaller trees grow in the under story (layer between the canopy and the forest floor). The emergent trees and those in the canopy receive most of the light and therefore grow tall. •Below the canopy, competition for sunlight is fierce. Trees in the under canopy are shorter as they are in the shade. •Only 1% of sunlight reaches the forest, so growth in the shrub layer is more limited. •The way the rainforest is divided into 4 distinct layers is all due to the availability of light which plants need for photosynthesis.

	•Canopy layer Formed by the crowns of the tall trees and • •contains a mass of branches, Leaves, flowers and fruit. • •Conditions in the canopy vary, and include: • - Hot sunshine - Heavy rainfall - Tropical storms
	•Middle layer The Vegetation here is more sparse. The trees tend to have pointed crowns and, when a giant tree falls, they grow quickly to fill a gap in the canopy • •Conditions within the forest on more or less constant: - There is little variation in temperature - The air is moist and still - Rain on the canopy drips to the forest floor several minutes later - A breeze is rare, even during storms
	Shrub layer Scattered shrubs, saplings (young trees) and ferns.
	Herb layer A few non-woody, soft stemmed plants with thin leaves.
	Leaf litter •Thin layer covers the forest floor.
	Soil layer •Most roots grow in the top 10 centimetres where the nutrients are found.

	Peculiarities
	•Some trees grow tall and straight, others (lianas) just loop around tree trunks to reach sunlight. •The soil is poor so the plant roots grow close to or even on the surface. •The tallest trees have developed outer roots called buttress roots to stop them toppling over. •Air plants (epiphytes) forget about roots and perch on high branches. •Species like ferns adapt to this life growing in the shade. •On the ground insects munch and bacteria works fast releasing nutrients from all waste material.

	Mining in the Amazon
	Miners (garimpeiros) have caused damage to the ecosystem by cutting down large areas of forest and by using chemicals to purify their metals. They use enormous amounts of mercury to purify the gold and this toxic metal is released into the rivers. There is a large amount of iron ore which is exported for steel making.

	Logging
	There’s great demand for tropical hardwoods such as mahogany and rosewood. Random logging means that for every tree cut down, at least 30 more may be destroyed in the process. Five million hectares are lost in the Amazon every year.

	Cattle Ranching
	Large areas have been cleared for cattle. Since 1950, two-thirds of the Amazon’s lowland forest has been turned into pasture for grazing and the production of beef. The quality of the grass has declined as the nutrients from the soil are lost.

	Peasant Farming
	Since 1970 the Brazilian government, concerned about overcrowded cities has encouraged citizens to move to the rainforest, giving them land to clear for subsistence farming. The soil has proved infertile because without the forest canopy, there’s nothing to replenish the soil with nutrients.

	Sustainable Management Strategies
	Forest Reserves. •Areas of forest that are completely protected from all activities. •They are often close to areas known as extractive reserves. Afforestation •This is planting of new trees once mature trees have been felled. •This ensures the canopy is maintained. Agro-forestry •Practice of growing trees in combination with agricultural crops. •Farmers take advantage of the protective canopy and nutrients from decomposing plant matter. Selective Logging •Individual trees felled only when they have matured. •Helps preserving canopy layer and helps slower growing hardwoods. Tree Measuring •Felling should occur only when tree has reached a specific height. •This ensures younger trees have a chance of survival. Education •A good strategy is to educate the users of the forest to become its protector.

	Destroying the rainforests
	•The main reason is to clear the land for farming, usually by burning the trees down. •Companies exploring for oil and metal add to the problem. •Logging is also very damaging to find 1 hardwood tree they cut down an average 30 trees. •Government plans don’t help, for example by building motorways. •Local tribes suffer, their homes are destroyed or moved, food is harder to find. •The soil suffers because when the trees are cleared soil quickly becomes useless. Heavy rain washes nutrients away and no dead leaves are left to make more. •The animals suffer, their food disappears, their homes are destroyed, they are hunted easier. •Everyone suffers, millions of species are being killed off including plants that cure diseases. Burning the forest produces carbon dioxide which helps speed up global warming.

	Savanna Grasslands
	Climate in the Savanna
	Wet Season •The rainy season is between May and October 90% of the annual rainfall can fall during this period, often in heavy down pours. •Temperatures are around 25ºC Dry Season •Dry season is from November to April. There’s little or no rain during this time. •Temperatures can be over 30ºc. •This creates a harsh environment for plants and animals. Wind Direction •Moderately strong trade winds blow across the savanna. •They blow from a north-easterly direction. •They control how far north the rain gets each year.

	Wet Season
	•This is the growing season for plants, there are not many trees because trees need a lot of water, those that grow are adapted to drought. •There are lots of large animals (more than 40 species of herbivores). Many travel long distances in the dry season to find grass. •Bushes have thorns instead of leaves to prevent water loss and protect them from herbivores. •Grass grows fast up to 3 metres tall. •Soil gets soaked in the wet season and baked in the dry season so a brick-hard layer form below the surface, this stops roots from pushing down so trees must root in cracks. •Acacias have small leaves covered in wax to cut down water loss, it has long tap roots to reach moisture in the dry season.
	Dry Season
	•Trees lose their leaves to prevent water loss. •The baobab tree stores water inside its huge trunk during the wet season this helps it survive the dry season. •The thick bark of the trees help them to withstand the many fires that occur in the dry season. •There is no food so the large animals have moved away. •The local inhabitants burn the grass because the ashes make the soil more fertile.
	Climate Graph of the Savanna.

	Savanna grassland
	Savanna grasslands are found between tropical rainforests and deserts. Savanna areas include Northern Australia, Central Africa (Kenya) and Northern South America. Savanna regions are dense grasslands with a scattering of trees and/or bushes. All savanna areas have a wet and a dry season. In the wet season the vegetation grows tall, while in the dry season the vegetation dies back.

	Trees in savanna grasslands
	Many plants in the savanna are xerophytic (drought resistant) like the acacia tree with small waxy leaves and thorns. Another drought resistant tree is the baobab which has a swollen, hollow trunk that stores water. An ancient baobab tree in Zimbabwe is so large that up to 40 people can shelter inside its trunk!

	Elephant Grass
	•The grass grows very tall, anything from 3 to 5 metres in height. • The individual blades of grass curve away from the strong sunlight. • At the end of the wet season the grass turns yellow and dies back, putting nutrients back into the soil. • Seeds lie dormant until next wet season.

	Acacia Tree
	•Has a flat top or crown. • Can grow up to 20 metres in height. • It has a very long tap-root up to 35 metres reaching down to the underground water. • Has small waxy leaves and thorns to help reduce water loss through transpiration.

	Baobab Tree
	•Giant tree can grow up to 25 metres tall. • Can grow an incredible 10 metres wide. • The trunk can be wider than the crown. • Water is stored in the trunk during the drought protected by a very thick bark. • Has small waxy leaves and thorns reduce the loss of water through transpiration.

	Savanna Grasslands – Human Activity
	Fire • Some are started by lightning strikes, many are started deliberately. • Ash makes the soil more fertile. • They can get out of control. Hunting • People hunt for food. • Specially for zebras and wildebeests. Agriculture • More and more land is used for growing crops and grazing cattle and goats. Deforestation • Population growth has resulted in increased demand for wood. • Wood is used for cooking and heating so trees are cut down. Tourism • Tourists come to see wildlife. • Specially animals like lions, cheetahs, giraffes and rhinos.

	Savanna Grasslands Causes of Desertification
	Overcultivation • Population growth has put pressure on the farmland to produce more food. • This extensive use of land exhausts the nutrients. • Crops no longer grow and soil is lost through wind and water erosion. Overgrazing • Permanent and nomadic pastoral farmers are having to let livestock graze on marginal land closer to the desert. • When the protective vegetation cover is eaten away the soil becomes vulnerable to erosion. Deforestation • 80% of domestic energy comes from burning firewood. • Increased population means increased demand for wood. • Land is cleared of trees, again the soil becomes vulnerable to erosion. Climate Change • Climate has become much drier over the last 40 years. • Less rainfall means poorer grazing and lower crop production. • Underground water reserves have been used up.

	Coniferous Forests
	Climate in the Coniferous Forests
	Temperature •Long severe winters. •Temperatures can fall as low as -40º and are below 0ºc for at least six months of the year. •Short summers, temperatures can reach max. 20ºc •Only 4 months a year are totally free of frost. •They have a very short growing season. Precipitation •Annual precipitation is 300-900 mm. •Most are heavy snowfalls in the winter months. Wind Direction •Strong northerly wind from the Arctic.

	Types of Coniferous Trees
	Trees adapted to cold.
	•Trees grow very close together, helps keep trees warm in winter. •Conic shop is distinctive. •The drooping branches are flexible and don’t break under the weight of heavy snow. •The conical shape also helps trees to shed snow. •Thick barks protect the tree from extreme cold. •Seeds are formed in a protective cone. •When summer comes the cone bursts open to release the seeds. •Needles remain on the tree all year round. •As soon as temperatures are warm enough for growth, these needles start the process of photosynthesis immediately. •The narrow surface of each needle helps prevent moisture loss through transpiration. •The dark colour of the needles helps the tree absorb heat from the sun more easily.

	Forestry
	Timber •About half the timber felled is used in house-building and for doors, window frames and furniture.
	Leisure and Recreation •Skiing in winter, walking, camping and outdoor summer activities.
	Bio-energy •Waste materials from the timber and pulp industries are burnt as a source of fuel.
	Pulp and Paper •Wood fibres or pulp are used in the production of paper and card.