Option Unit: Living Things
Option Unit: Living Things
Exam Date: 22nd May
Common 4/6 mark questions
The links between Living and Non Living things in Ecosystems
You need to be able to explain (this may involve annotating a diagram) the interactions within an ecosystem. The interactions you explain could include:
- Leaves and vegetation growing through photosynthesis
- Dead matter decaying and returning nutrients to the soil which provides nutrients for new growth
- Living matter in the soil speeding up this decomposition.
- Heat causing rainfall which provides moisture for growth;
- Heat and moisture encourage decay;
- Decaying material may provide habitat for living things.
These interactions should be linked to the Amazon rainforest where it is hot and wet with dense vegetation. These three things are key components in the interactions above.
Biomes and Climates
Biomes are very large areas on the earth’s surface, with animals and plants adapting to their environment. Biomes are often defined by factors such as climate, relief, geology, soils and vegetation.
Examples of biomes:
Tropical forests
Location: Near the equator in Central and South America, parts of Africa and Asia. Characteristics: Hot, humid with equatorial climate and biggest biodiversity. Almost half of the world’s species (plants and animals) live there. The trees are mostly hardwood.
Tropical Grasslands
Location: Central Africa (Kenya, Zambia, Tanzania), northern Australia and central South America (Venezuela and Brazil).
Characteristics: Hot and dry, mainly grass, scrub and occasional trees. This biome has two distinct seasons — a dry season and a rainy season. During the dry season the vegetation dies and re-appears rapidly during the rainy season.
Desert
Location: The Sahara Desert is the world’s largest desert, located in North Africa.
Characteristics: Very hot and dry with very little rain.
Temperate deciduous forests
Location: Usually across Europe and USA contain trees that lose their leaves and are Characteristics: These have a temperate maritime climate, usually with mild and wet weather.
Tundra
Location: Surrounds the North and South poles.
Characteristics: Extremely cold climate, temperatures often reaching about -50°F in the winter, supporting only a few plants and animals. Tundra covers about one-fifth of the Earth's land surface.
Case Studies
The Use of Ecosystems - Amazon Rainforest, Brazil
The Amazon Rainforest has been used in many ways.
Logging: Rainforest trees are mainly hardwoods. These can be very valuable on the international market. Unfortunately, to get to certain types of tree, logging companies destroy all the other vegetation around them.
Ranching: Large-scale forest clearance has taken place to make way for huge cattle ranches, as these are also a profitable industry for the country. The cattle quickly erode the fragile, and now unprotected, soil. The farmers are not interested in the wood for sale, they often just burn it.
Damming: To provide power for industries such as the mines and papermills, large dam schemes have been introduced. An example of this is the proposed Belo Monte Dam.
Mining: the Northern Amazon rainforest is rich in minerals, such as bauxite, iron ore and even some gold. This has meant that vast areas of rainforest have been cleared to allow mining to occur. Settlements have grown up, such as Carajas and Manaus purely based on the mining industry.
Sustainable Management of an Ecosystem – The Amazon Rainforest, Brazil
The rainforests do have a huge number of very useful resources that can be used without damaging the ecosystem.
Shifting cultivation is a traditional, sustainable method of agriculture which has been practised by indigenous tribes for centuries.
- A small area of land is cleared and the vegetation burned, providing a source of nutrients from the ash.
- For a few years the soil remains sufficiently fertile for the tribe to grow crops.
- When the soil's fertility is exhausted, the tribe moves on and clears another small area of forest.
- The original area is regenerated, as it receives nutrients and seeds from surrounding vegetation.
- As no lasting damage occurs, this method of agriculture is sustainable.
- It is sometimes called 'slash and burn' agriculture.
Agro-forestry - growing trees and crops at the same time. This lets farmers take advantage of shelter from the canopy of trees. It prevents soil erosion and the crops benefit from the nutrients from the dead organic matter.
Selective logging - trees are only felled when they reach a particular height. This allows young trees a guaranteed life span and the forest will regain full maturity after around 30-50 years.
Education - ensuring those involved in exploitation and management of the forest understand the consequences behind their actions.
Afforestation - the opposite of deforestation. If trees are cut down, they are replaced to maintain the canopy.
Forest reserves or national parks - areas protected from exploitation.
Monitoring - use of satellite technology and photography to check that any activities taking place are legal and follow guidelines for sustainability.
Eco-tourism –this is responsible travel to fragile, unspoilt, and usually protected areas that strive to be low impact and (often) small scale. The only way for ecotourism to succeed is if the area remain undamaged and therefore protection is a priority.
Evidence of Unsustainable Management
The Millennium Ecosystem Assessment looked at ecosystem change. They found:
- Over the past 50 years humans have changed ecosystems more rapidly than any other time period. Irreversible loss.
- The changes made have led to human wellbeing but future generations will be enjoy the same benefits.
- The damage to ecosystems could grow worse.
- In order to reverse degradation significant changes in policies and practices are needed.
Consequences of unsustainable management
Belo Monte Dam, Brazil.
Consequences on the environment:
- An area of more than 1,500 square kilometres would be devastated – habitats destroyed, species lost.
- Large scale deforestation – soil unprotected so increased erosion. No trees so no source of nutrients so soil becomes infertile. The interactions are broken down.
- Large scale deforestation reduces the storage of carbon dioxide in trees and the reservoir created will be a significant source of greenhouse gas emissions due to decomposing vegetation.
Consequences on people:
- Officially 19,000 people would be forcibly displaced for the Belo Monte dam to be built.
- Loss of traditional lifestyles and access to the land
- Rivers will become polluted which impacts water source
- Fish migration patterns will change which means a loss of food/materials gathered
- Loss of food source hunted from the forest.