The Living World

Seite 1

Ecosystems.

ECOSYSTEM: a unit that includes all the living and non-living parts in an area.

> if one part changes, it impacts the all the other parts.

ORGANISMS IN ECOSYSTEMS:

Producer: uses sunlight energy to produce food (plants).

Consumer: gets energy by eating other organisms (animals; herbivores, omnivores, carnivores).

Decomposer: gets energy by breaking down dead material, dead producers etc. (bacteria and fungi).

THE NUTRIENT CYCLE:

dead material decomposed and nutrients released into the soil.

nutrients taken up by plants (producers), plants may be eaten by consumers.

when producers/consumers die, nutrients are returned to the soil.

GLOBAL DISTRIBUTION OF ECOSYSTEMS:

Tropical Rainforests: north and south of the equator, within the tropics.

Hot Deserts: around the tropics [of Cancer and Capricorn].

Temperate Deciduous Forests: above or below the tropics.

TROPICAL RAINFORESTS:

Areas: Central and South America, central Africa, south east Asia.

Climate: hot and wet with no definitive seasons.

Soil: not very fertile due to heavy rain washing nutrients away.

Vegetation Structure: shrub layer > undercanopy > canopy > emergents.

Plant Adaptations:

Thick, waxy leaves with pointed tips (drip-tips) so water runs off so the weight doesn't damage the plant.

Tall trees have buttress roots for support.

Lianas (climbing plants) use tree trunks to climb up to the light.

HOT DESERTS:

Areas: North Africa, Middle East, South West USA, Australia.

Climate: hot and dry; little rainfall and extreme temperatures.

Soil: shallow with a gravelly texture; not very fertile.

Vegetation Structure: sparse due to lack of rainfall; plants include cacti and thornbushes.

Plant Adaptations:

Roots either very long to reach deep water or spread out near the surface.

Cacti have swollen stems to store water and thick skin to reduce water loss.

Small leaves to reduce water loss.

Seeds only germinate when it rains - they grow, flower and release seeds very quickly to use the scarce water.

TEMPERATE DECIDUOUS FORESTS:

Areas: Europe, China, Japan.

Climate: mild and wet; distinct seasons with rainfall all year round.

Soil: deep and fertile due to a thick layer of leaf fall.

Vegetation Structure: undergrowth > shrub layer (small trees) > tree layer (tall trees)

Plant Adaptations:

Deciduous trees reduce water loss in the months where it's harder to get water due to frozen soil and lack of light for photosynthesis.

Wildflowers grow in spring before the trees grow leaves and block out light.

Seite 2

Deciduous Forest Case Study - New Forest.

NEW FOREST IN HAMPSHIRE:

National Park in Hampshire, south England, that covers 375km.

USES:

Timber and Timber Products: produces 50, 000 tonnes of timber a year; local mills making fencing products from the timber.

Recreation: 20 million tourists visit each year for walking, cycling (100 miles+ of cycle tracks), wildlife watching (the New Forest ponies roam wild), horse riding and fishing.

SUSTAINABLE MANAGEMENT:

Areas cleared of trees are replanted or restored to other habitats.

Walkers and cyclists encouraged to stick to paths to limit erosion.

Dogs not allowed near animal breeding sites to conserve wildlife.

National Park Forest Centre encourages people to act responsibility, like shutting the gate and not littering.

Seite 3

Tropical Rainforest - Deforestation.

CAUSES OF DEFORESTATION:

Farming: slash and burn technique (cut down vegetation, left to dry, then burnt) used to clear forest for subsistence farms or cattle ranches.

Mineral Extraction: trees cut down to expose ground and clear access routes to mines.

Commercial Logging: trees cut down for money.

Population Pressure: trees cleared to create more land for settlements.

Road Building: more settlements and industry lead to more roads, so trees have to be cleared.

IMPACTS OF DEFORESTATION:

Environmental:

Destroyed habitats reduces biodiversity.

No trees means soil can be washed away (soil erosion).

Soil can be washed into rivers, killing fish and making water undrinkable.

Increased run-off, nutrients in soil washed away so nutrient cycle breaks.

Less trees mean less CO2 is being removed from the atmoshpere.

Burning vegetation produces CO2.

Social:

More jobs for locals -quality of life improved.

Some native tribes forced to move when their land has been cleared.

Conflict between conservationists and logging/mining companies.

Economic:

Jobs created.

Money is made from selling timber, mining and farming.

Political:

Pressure from foreign governments to stop deforestation.

Seite 4

Tropical Rainforest - Sustainable Management.

Sustainable management allows the land to be maintained for future generations whilst allowing the current generation to get what they need.

SELECTIVE LOGGING:

Only the oldest trees are cut down.

This means the overall structure of the forest is kept so it can be used in the future.

REPLANTING:

New trees planted to replace old ones that had been cut down - trees for the future.

REDUCING DEMAND FOR HARDWOOD:

High demand for hardwood (like mahogany an rosewood) from MEDC's due to it being good for furniture.

Some hardwood species are becoming rarer, so countries are trying to reduce the demand so they are still some left for future generations.

Strategies include heavily taxing imported hardwood or banning its sale.

EDUCATION:

Educating the locals about the impacts of deforestation and ways to reduce the impacts decreases their effect.

Also, by educating them about alternative ways to make money.

ECOTOURISM:

Provides a source of income for local people so they don't have to log or farm to make money.

Small-scale activity - small number of visitors so environmental impact is low.

REDUCING DEBT:

Rainforests are often in LEDC's and LEDC's often borrow money from MEDC's; LEDC's will often allow logging, mining and farming to help pay back the debt.

MEDC's reducing the debt owed by the LEDC's would mean this doesn't have to happen.

Conservation swaps can also happen: part of a country's debt is paid off in exchange for investment in conservation of the rainforest.

Example: in 1987 some of Bolivia's debt was paid off by a conservation company in exchange for creating a rainforest reserve.

PROTECTION VIA LAWS:

Laws can be used to ban illegal logging, ban logging of certain tree species etc.

Seite 5

Tropical Rainforest Case Study - The Amazon.

BACKGROUND INFO:

The Amazon rainforest covers over 8 million km2 in South America.

Since 1970, over 600, 000km2 has been cut down.

CAUSES OF DEFORESTATION:

Cattle Ranching - 60%

Subsistence Farming - 33%

Logging - 3%

Mining, Road Construction and Urbanisation - 3%

IMPACTS OF DEFORESTATION:

Environmental:

Habitat destruction and loss of biodiversity - the number of endangered species in Brazil increased from 218 in 1989 to 628 in 2008.

The Amazon stores 100 billion tonnes of carbon which, with deforestation, will be released as CO2 and cause global warming.

Social:

Local livelihoods have been affected/destroyed.

Tribes such as the Guarani Tribe in Brazil have been forced to move due to their land being taken for cattle ranching.

Conflict between landowners, farmers and natives - in Peru 2009 there were riots over rainforest destruction.

Economic:

Farming makes a lot of money - in 2008, Brazil made $6.9 billion from trading cattle.

Mining creates jobs for local people - the Buenaventure Mining Company in Peru employs 3100 people.

SUSTAINABLE MANAGEMENT STRATEGIES:

Replanting - Peru plans to replant 100, 000km2 before 2018.

Reduce number of hardwood trees (like Mahogany and Rosewood) felled.

Ecotourism - the Madre de Dios region in Peru has 70 lodges and 60, 000 visited in 2007.

Protection Laws - the Brazilian Forest Code says landowners have to keep 50-80% of their land as forest.

National Parks - the Central Amazon Conservation Complex in Brazil covers 25, 000km2 of protected land.

Reducing debt - in 2008 the USA reduced Peru's debt by $25 million for conservation of the rainforest.