Ecology
- Created by: holly6901
- Created on: 09-05-19 16:31
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- Ecology
- An ecosystem is made up of living (biotic) and non-living (abiotic) parts. In an ecosystem, there are different levels of organisation, individuals, populations and communities.
- Competion
- Plants often compete for water and mineral ions (minerals) from the soil, as well as for light and space.
- Animals often compete for food, mates and territory.
- Interdependence
- There is interdependence between different species. This means that one species may rely on another species for different things, such as: shelter, food, seed dispersal and pollination
- Food chains
- Food chains show the feeding relationships within a community
- Producers are eaten by animals called primary consumers
- .Primary consumers are eaten by secondary consumers.
- Secondary consumers are eaten by tertiary consumers
- .An apex predator is at the top of the food chain.
- :Food chains nearly always begin with a producer that makes its own food. This is usually a green plant or algae that can photosynthesise.
- Predator-prey graphs
- Predator-prey graphs show the cyclical nature of predator and prey populations in stable communities. A classic example is that of the Canada lynx and snowshoe hare:
- 1. An increase in the hare numbers means more food is available for the lynx, so lynx numbers also increase.
- 2.The increase in lynx numbers means that the hares have more predators, so the hare numbers decrease.
- 3. The lynx then have less food available so their numbers decrease.
- 4. The decreasing lynx numbers allows the hare numbers to increase again, and the cycle repeats.
- Assessing ecosystems
- Transects can be used to investigate the effect of a factor on the distribution of a species.
- Quadrats are square frames that can be used to estimate population sizes.
- 1. Divide the habitat up into a series of quadrat-sized cells.
- 2. Randomly select a given number of cells, then go out into the habitat and place the quadrat in these positions.
- 3. To evaluate the quadrat contents, either count the number of individual organisms of interest or record the percentage of the quadrat taken up by an organism (e.g. grass).
- 4. The samples from the quadrat are used to estimate the total population in a given area:
- population = number counted x (total survey area / area sampled)
- Recycling materials
- The water cycle
- This cycle describes how water moves on, above or just below the surface of our planet between different locations, such as rivers, oceans and the atmosphere.
- 1. Water evaporates from the Earth’s surface, before rising up into the atmosphere.
- 2. Once in the atmosphere, the water vapour cools and condenses into either rain or snow. This eventually returns to the Earth’s surface.
- 3. The rain or snow will either become surface runoff (water flowing off land) or will travel through the earth as ground water.
- 4. Plants take up water through their roots.
- The carbon cycle
- When organisms die, the carbon is recycled so that it can be used by future generations.
- 1. Carbon is removed from the atmosphere by producers (e.g. algae) who use it in photosynthesis.
- 2.By consuming plant matter, animals obtain carbon compounds.
- 3. Carbon is returned into the atmosphere (as carbon dioxide) because of the respiration that happens in plant and animal cells.
- 4. When animals and plants die, decomposers return the carbon locked in their bodies back to the atmosphere via decay.
- 5. Combustion of fossil fuels is another source of carbon entry into the atmosphere.
- The water cycle
- Humans and biodiversity
- An awareness of the detrimental nature of these activities has existed for several decades.
- However, because of the pursuit of economic gain, the warning signs have largely been ignored.
- For some time, and especially since the industrial revolution, humans have conducted many activities that have caused a severe decline in biodiversity on a global scale.
- However, because of the pursuit of economic gain, the warning signs have largely been ignored.
- Attitudes have recently begun to change and measures are being taken to prevent further damage being done and to regain pre-existing biodiversity.
- Waste management
- Toxic herbicides and pesticides used in farming, buried nuclear waste and household waste in landfill sites are all land pollutants.
- Smoke and gases are being added into the atmosphere constantly, particularly by power stations and cars.
- Sewage and toxic chemicals, which are produced by industrial practices, as well as excess fertiliser from agriculture, all find their way into the Earth’s water sources.
- Land use
- Peat is a deposit of partially decayed plant matter, which accumulates in bogs.
- Here, carbon remains in the plants instead of being released into the atmosphere.
- The destruction of peat bogs has become more common, resulting in the burning or decay of peat.
- This releases the stored carbon into the atmosphere in the form of the greenhouse gas, carbon dioxide.
- Another negative impact of peat bog destruction is the loss of biodiversity within the habitat.
- This releases the stored carbon into the atmosphere in the form of the greenhouse gas, carbon dioxide.
- Peat bogs are being destroyed for the following reasons:
- To free up land for farming, which requires the bogs to be drained. This draining process stimulates peat decay.
- To burn the peat for fuel.
- To sell the peat to gardeners as garden compost.
- Peat demand can be reduced by gardeners using peat-free compost, such as manure or bark chippings.
- Consequences of deforestation
- Deforestation causes a loss of ecosystem services provided by forests, such as erosion prevention, flood control and food provision.
- The burning of trees and decomposition of wood increases the rate of carbon dioxide that is released into the atmosphere.
- As less photosynthesis is taking place, less carbon dioxide can be removed from the atmosphere.
- Forests are often chopped down to be replaced by agriculture, with the purpose of growing rice or farming cattle.
- These activities produce methane, which is a greenhouse gas.
- Deforestation destroys habitats. This causes biodiversity to be lost.
- Peat is a deposit of partially decayed plant matter, which accumulates in bogs.
- Co2 levels
- Carbon dioxide is removed from the atmosphere naturally by green plants and algae during photosynthesis.
- Carbon dioxide is released into the atmosphere naturally as the waste product of respiration.
- The greenhouse effect
- The greenhouse effect describes how greenhouse gases (e.g. carbon dioxide and methane) act as a natural, insulating layer in the atmosphere, re-radiating most of the heat energy which has been reflected off the Earth’s surface back towards Earth.
- The consensus among climate scientists is that the greenhouse effect is causing global warming.
- As the atmospheric concentrations of greenhouse gases rise, there is a risk that the greenhouse effect could become too strong and the temperature could rise too high.
- The consequences of global warming
- Rising sea surface temperatures are causing bleaching of sensitive corals.
- Malaria-carrying mosquitoes have already spread to several European countries.
- It is possible that malaria and similar exotic diseases will become an established part of life as far North as the UK in the near future.
- Extreme meteorological events, such as floods, droughts, severe storms and wildfires are happening more often.
- The rate at which the climate is changing makes rapid adaptation key to avoiding extinction.
- Melting ice causes sea levels to rise, which could flood coastal habitats forever, losing the land and associated biodiversity.
- Many migration patterns are likely to be altered by global warming.
- Increased acidification (becoming more acidic) of the oceans is making it harder for corals to build their skeletons.
- Maintaining biodiversity
- Efforts are being made into the protection and regeneration of rare habitats.
- Breeding programmes for endangered species can be important for preventing extinction events.
- Farmers are being incentivised to maintain field margins and hedgerows, as these habitats can support biodiversity.
- Recycling slows down the expansion of landfill sites and reduces the need to extract new natural resources.
- Government targets can be related to things like deforestation and emission reductions.
- An awareness of the detrimental nature of these activities has existed for several decades.
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