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.
    • 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.
      • 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.
        • 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.
      • 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.

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