B4a - Ecology in the local enviroment

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GCSE BIOLOGY (B4) Mind Map on B4a - Ecology in the local enviroment, created by Chloe.Sharland on 06/10/2014.
Chloe.Sharland
Mind Map by Chloe.Sharland, updated more than 1 year ago
Chloe.Sharland
Created by Chloe.Sharland over 10 years ago
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B4a - Ecology in the local enviroment
  1. Sampling Methods
    1. A population is the total number of individuals of the same species that live in a certain area.
      1. The size + distribution of a population can be measured using one or more techniques: Pooters, Sweepnets, difficult number, Pitfall traps, Quadrats.
        1. When sampling you must make sure you take a big enough sample, reliable & sample randomly
        2. Estimating Animal Populations
          1. Animal populations are difficult to sample and measure because most species are highly mobile and are not easily visible because they are usually hiding from predators.
            1. One method is the capture, recapture method sometimes called the Lincoln index: Animals are caught humanely, the animals are marked, the marked animals are released, a second sample is obtained which will contain so marked animals and some unmarked. The numbers in each group are again counted.
              1. The following formula can then be used to estimate the total population size in the habitat: No in 1st sample x no in 2nd sample / no in 2nd sample which were previously unmarked.
                1. Certain assumptions are made when using the capture/ recapture data. No death, immigration, emigration. Each sample is collected in exactly the same way without bias. The marks given to an animal do not affect their survival rate.
                2. Using Transects
                  1. Sometimes an enviromental scientist may want to look at how species change across habitat, or the boundary between them. This needs more systematic method:
                    1. A line such as a tape measures is laid down, regular intervals marked
                      1. A small quadrat is laid next to the line and the number of plants of the different species is estimated or counted. This can sometimes be done by estimating the percentage cover.
                        1. The quadrat is moved along at regular intervals and the plant populations estimated and recorded at each point until the end of the line.
                          1. The height of a particular kite shows how abundant that particular species is at that point.
                        2. Zonation
                          1. Zonation is described as a gradual change in the distribution of a species across a habitat. Changes usually result from a physical factor changing.
                          2. Keys
                            1. Correctly identifying species in a sample can be difficult. Using keys can help to identify organisms. Does it have six legs?
                            2. Important Ecological terms
                              1. Population - the number of individuals of a species in a defined area.
                                1. Community - the total number of individuals of all the different populations of organisms that live together in a habitat any one time.
                                  1. Ecosystem - A physical environment with a particular set of conditions, plus all the organisms that live in it. The organisms interact through competition and predation. They are affected by the physical factors present in the ecosystem. Some ecosystems are still unexplored, with possible undiscovered species.
                                    1. Biodiversity - the variety of different species living in a habitat.
                                      1. Habitat - the part of the physical environment where a plant or animal lives. There are many types of habitat, each with particular characteristics. An organism must be well suited to it's habitat to be able to compete with other species for limited resources. Organisms that are specialised in this way are restricted to that type of habitat because their adaptations are unsuitable elsewhere. Organisms are not normally distributed at random in a habitat. They may often be clumped into specific areas.
                                      2. Natural and Artificial Ecosystems
                                        1. Natural ecosystems - not man-made. They change over time. Examples of natural ecosystems are native woodlands or lakes.
                                          1. Artificial ecosystems - man-made and carefully controlled to keep the conditions constant. Examples include fish farms and foresty plantations.
                                            1. Biodiversity in natural ecosystems is always greater than in artificial ones.
                                              1. Natural ecosystems have high biodiversity many different species of plants and animals co-exists in the same environment. Artificial ecosystems are designed for a particular purpose. A market gardener growing a crop in a greenhouse uses fertilisers, weedkillers and pesticides to prevent other organisms from growing alongside his crop. The biodiversity in this ecosystem will be low.
                                              2. Comparing Ecological Habitats
                                                1. Two habitats can be compared by sampling using a quadrat. First the plant and animal species in a 1m2 quadrat must be identified and then the population of each species must be counted. The process is repeated several times to get a large, reliable sample.
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