- Created by: Procrastination101
- Created on: 20-02-19 18:48
Ecosystem = A complex natural system made up of plants, animals and the environment.
Global scale ecosystems = biomes
Producers - (e.g plants) convert energy from the Sun by photosynthesis into carbohydrates for growth
Consumers - get their energy from eating producers, creating direct links within ecosystems (food chains) and more complex food webs
Decomposers- (e.g bacteria and fungi) break down dead plant and animal material to add to nutrients within the soil - nutrients which are used by plants in nutrient cycling.
Impacts of change on ecosystems - Agricultural fertilisers can lead to eutrophication; wood cut down, destroying habitats for birds and affecting nutrient cycle; ponds may be drained to be used for farming; hedgerows removed to increase size of fields, destroying habitats; extreme weather events like droughts can be devastating to freshwater ponds, killing fish, plants and birds which are dependent upon them.
Large-scale global ecosystems
Tundra- mainly located between the Arctic circle: cold, windy and dry conditions support low growing plants easily damaged by developments.
Polar- located around North & South Poles: low temperatures (below -50) and dry conditions prohibit most plant and animal life.
Tropical rainforest- mainly close to equator: high temperatures and heay rainfall.
Desert- High daytime temperatures, low night-time temperatures and very low rainfall restricts plant & animals to highly specialised species.
Temperate grassland- 30-40 degrees north & south of equator: Warm, dry summers and cold winters support grasses for grazing animals.
Tropical grassland- between 15-30 degrees north & south of the equator: Distinct wet and dry seasons support large herds of grazing animals and their predators.
Mediterranean- isolated locations south of equator: Hot, sunny, dry summers and mild winters support olive groves & citrus fruits.
Environmental characteristics of rainforests
- Shrub & ground layer - limited to ferns, woody plants and younger trees (lack of light). Bacteria and fungi rapidly rot fallen leaves, dead plants and animals. Thick butress roots help to spread the weight of towering trees above.
- Soils - cycle nutrients rapidly to support new growth. Are iron-rich and infertile because nutrient cycling is so rapid. Once rainforests are cleared, their soils are prone to rapid leaching where minerals are lost in solution.
- Lower tree canopy - shaded, less substantial trees waiting to take advantage of the next available light space. Interlocking spindly branches and climbing woody creepers (lianas) form green corridors along which lightweight animals can travel.
- Middle canopy - Each mushroom-shaped crown has an enormous photosynthetic surface of dark, leathery leaves. Drip tips help them shed water quickly and efficiently.
- Top canopy - Hardly exposed emergent trees with straight branchless trunks receive the most light.
Managing tropical rainforests
Sustainable commercial management
- Selective logging and replanting -
- Conservation and education - encourages preservation of rainforests in national parks and nature reserves for scientific research and tourism (e.g. in Brazil)
- Ecotourism - Introduces people to the natural world and provides long-term income to local people and governments.
- International agreements - recognise the global importance of rainforests in combating climate change. They include 'debt-for-nature-swapping' agreements whereby some donor countries and organisations reduce their debt repayment demands in return for a halt to deforestation.
The Forest Stewardship Council (FSC) promotes sustainably managed forestry through education programmes and its FSC-labelled products.
Characteristics of cold environments
Climate - Extremely low winter temperatures, strong winds, low snow totals
Soils- Permafrost covered by ice
Plants- Few mosses and lichens on the fringes of the ice
Animals- Polar bears with thick fur and foot pads, Antarctic penguins rear their young on land
Climate- Winter temperatures drop to -20, warm brief summers, higher snowfall (on coast)
Soils- Surface permafrost melts in summer causing waterlogging
Plants- Low-growing, flowering plants with special adaptations (hairy stems insulate plant)
Animals- Arctic fox & hare, summer birds, insects (due to more food options, less extreme climate)
Cold environments under threat
Risk of economic development
Rich reserves of oil & gas remain in high demand, but their exploitation requires the construction of access roads through forests and across tundra regions, supply bases and settlements for workers, and drilling equipment and pipelines.
Why cold environments need protecting:
- Important unpolluted, unspoilt, outdoor laboratories for scientific research ( e.g climate change).
- Many indigenous people (e.g Arctic Inuit) depend on the wildlife and survive by hunting and fishing.
- Wild beauty and potential for adventure attracts tourism which benefits the economy.
- Opportunities for forestry and fishing.
- Home to a rich variety of birds, animals and plants.
Reducing risk to cold environments
Using technology: the trans-Alaskan oil pipeline
Crosses two mountain ranges and 800 rivers, is raised and insulated to prevent the hot oil melting the permafrost, whilst allowing caribou to migrate underneath, is engineered to slide during earthquakes but with automatic shut-off systems if there is a leak.
Action by governments: the Antarctic Treaty
- prevents economic development
- promotes scientific research
- controls tourism to keep disturbance at a minimum
Conservation groups such as the World Wide Fund for Nature (WWF - originally World Wildlife Fund) are working with oil companies, Inuit organisations, local communities and government regulators to plan for a sustainable future for the Arctic.