What is the Value of the Biosphere
The biosphere is the part of the Earth's surface inhabited by living things. A Biome is a world scale ecosystem, covers a huge area. The World can be divided into 9 major biomes, each one had its own widlife and vegetation. Location and characteristics of each biome are determined by its climate becasue climate affects growth of plants.
Temperature - Most important, varies with the seasons, length of growing season depends partly on temperature
Precipitation - Also important, forest with a huge biome needs lots of rainfall.
Sunshine hours - determines the amount of light available for photosynthesis.
Humidity - Controls rates of EVAPORATION.
Case studies to learn: Deserts, Rainforests, Savannah, Deciduous...... look for more.
Should be able to locate the case studies using both longitude and latitude, examples of countries in which they are located then describe the climate and characterstics.
Taking a closer look
Temperature - Average temperature is the main factor affecting plant growth. Temperature gradually decreases as you move away from the equator.Latitude increases temperature decreases. In the tropics the sun's rays are at a high angle in the sky for a whole year. These rays are concentrated over a smaller area than at the poles. Concentrated rays provide alot of heat and sunlight. Plants grow well so there is dense vegetation in the tropics. In polar areas the sun's rays are less concentrated. The lack of heat and light limits vegetation growth. Plant's are stunted and low growing.
Precipitation - More likely in some areas than others, precipitation happens in low - pressure belts where air masses converge (meet) and air rises.Two main areas of year roundfall occur at the Equator and at the mid latitudes, such as in the UK, forests grow in both these areas. In polar and desert areas, high pressure zones occur causing very dry conditions. Pressure belts changes with the seasons. Mediterranean and tropical areas sometimes become low - pressure zones and experience rainy seasons for nearly half the year.
A life support system
The biosphere is a life support system. It provides us with a wide range of goods, both for survival and for commercial use.
The biosphere also provides many vital services: regulating the composition of the atmosphere, maintaining the health of soil, regulating water within the hydrological cycle.
Many different people want to use the biomes in different ways, if the we overexploit forests or overharvest marine life, we aren't using the bioshphere ina sustainable way. If the biosphere is damaged it may fail to provide us with services. This can be disastrous.
Green lungs - Forests remove carbon dioxide from the atmosphere, this reduces global warming.
Water control - Forest protects watershed from soil erosion and intercept precipitation and by trapping silt forests keep water pure also reefs and mangroves provide protection from coastal storms.
Nutrient cycling - Forests provide leaf litter which forms humus. This makes th soil more fertile for growing crops.
Providing habitats for wildlife - Rainforests and reefs are very biodiverse, they provide 'homes' for a huge range of organisms.
Recreation - Reefs and Rainforests provide attractive scenery for tourism.
Delivering the goods
For indigineous peoples in the tropical rainforest biome, the biosphere provides almost anything: fuelwood, timber, herbs and food. They can grow subsistence crops: yams and millet, using the slash and burn method. Many see this as sustainable. The patch of forest is only used for 5 - 6 years, and once the soil is exhausted, the plot recovers with new forest developing.
Biosphere also provides many goods for commercial use. But there is a problem. Rival commercial users can destroy the rainforest for short - term gain. Giant companies exploit the forest by logging for timber or paper manufacture. They deforest the land to grow commercial plantationsof rubber, cocoa and palm oil. Commercial faremers also cut down trees to graze cattle or grow soya beans for biofuels. Drug companies search the forest for plants to make new medicines. Mining companies search the forest for minerals for oil.
Difference between Forested and Deforested
Forested - Use: Subsistence farming by indigenous local communities, Soil: protected from heavy rain and is nutrient rich and water moves slowly through the soil preventing flooding, Trees: Provides habitat for wildlife, tree roots bind the soil preventing land slides and wood provides fuel for local communities, Water: clean river water is fit for drinking, Economic and environmental gain: little economic gain, through the forest can support local indigenous communitiesv without suffering permanent damage.
Deforested - Use: Ranching, mainly for poor quality hamburger meat, Soil: nutrients lost from soil due to heavy rain, surface soil is washed away, blocking rivers and reservoirs and rapid surface runoff leads to flooding, Trees: loss of wildlife because of habitat destruction, without roots to hold the soil together landslides can occur and source of wood for fuel is lost, Water: water is muddy nd unsuitable for drinking, Economic and environmental gain: reasonable economic gain, but only short term, deforestation can cause desertification, the natural environment would struggle to recover.
Threats to the biosphere
If the the biosphere is not conserved properly then species would become under threat such as: mexican black howler monkey, yellow breasted capuchin, grey whale and riverrine rabbit.
Causes of bioshphere threats - The causes of threats to the bioshphere can be classified in two ways: Immediate causes, such as logging, over fishing and pollution. Root causes, such as rapidly expanding populations of people who use fuelwood.
A further root cause is economic development e.g. China and India which need a huge need for industrial raw materials. the living conditions are improving in these two countries which means that people will consume more food and fuel. All this puts strain on the biosphere.
Are we heading for mass extinction
Our impact on the planet is growing and we are threatening the ability of the biosphere to provide goods and services. Human impacts include: population growth. In the developing world , average population grwoth is 3% per year, Rising consumption of resources, such as food, oil, water and minerals, Human - induced climate change ( global warming) this is happening now, and is probably the biggest single threat to the biosphere, and the species that live in it.
Climate change - Global warming is occuring too rapidly for species to adapt, already there are: fewer fish in african lakes, plants flow earlier and there are new patterns of bird migration.
Reports suggest that rising temperature are also altering vegetation belts. These are beginning to shift towards the poles by 6km a decade.
Climate change will have many impacts on the biosphere, including these: Habitats will become increasingly fragmented ( broken up), Habitats will change due to rising temperatures, changing rainfall patterns, and rising sea levels, weather events like storms, floods and drought may become more common, Species may face extinction.
possible effect of 1-3°C
1°C - Impact on species: 10% of land species facing extinction, Impact on environment: Disapearance of glaciers and mountain ecosystems leads to loss of alpine plants.
2°C - Impact on species:15%-40% of land species facing extinction, Impact on environment: Oceans become moreacidic as more freshwater is added, bleaching of coral kills reefs.
3°C - Impact on species: 20%-50% of land species facing extinction including the many hotspots e.g. the Kenyan coast, Impact on environment: Sea level rises causing floodng of mangroves, drought in the Amazon kills the rainforest.
How can we conserve the biosphere
Act global - Countries can get together to develop wildlife consevation treaties. Two good examples are: The RAMSAR convention on conserving wetlands, adopted by 147 countries, CITES the convention on international trade in endangered species, adopted by 166 countrie, the CITES treaty lists the endangered species, the aim is to stop the trade in products such as elephant ivory or handbags made from crocodile skins.
Act local - National policies can be delivered in a local area, involving local people e.g. Biodiversity Action Plans (BAPs) protect natural vegetation in Great Britain. These plants act at a local level.
Act national - At a national scale, governments can set up protected areas, which help to conserve, manage and restore biodiversity. Community forests have been established to provide new areas of trees near major cities, there are many different types of conservation area all with different conservation aims.
Governments can also pay farmers to maintain and replant hedgerows and become more environmentally friendly.
Sustainable management involves:
- Conserving the ecosystem for future generations, by ensuring that it isnt used faster than it can be renewed, you could do this by zoning.
- Local people, so the ecosystem still provides them with resources.
- Schemes which train and educate local people, so that they can be involved in decision making, as the most important stakeholders.
- helping local people living in poverty. Sustainable schemes allow local people to make a living from ecotourism, or by carrying out activities in the buffer zone.
- Being environmentally friendly, it avoids practices like clear cutting, where the forest is completely destroyed. Trees are left to protect watersheds. Harvesting is selective, with only large trees logged. Only adult fish are caught.