• Created by: Abbih
  • Created on: 04-05-15 18:49
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  • Biodiversity
    • Species- A group of individual organisms very similar in appearance, anatomy, physiology, bio chemistry and genetics and whose members are able to interbreed freely to produce fertile offspring
      • Biodiversity can be considered by the differences between species
        • Biodiversity is considered on different levels
          • Biodiversity can be considered by the range  of habitats in which different  species live
          • Genetic variation between individuals of a species
    • Habitat- a place where individuals in a species live
      • Biodiversity can be considered by the range  of habitats in which different  species live
    • Includes all the different plant, animal,fungus and micro organism species    world wide, the genes they contain and the ecosystems of which they form a part
      • Not just about the number of different species, it also represent the degree of natures variety. It takes into account number of individuals and in how many places they can be found
      • Measuring Bio Diversity
        • Species richness- The number of species found in a habitat. You can estimate this by using a qualitative survey, this is done by taking samples, and making further observation in case your sample missed some species.
        • Species evenness- the relative abundance of individuals in each species. Measures in plants  by estimating percentage cover.
          • In Animals: Large animals are carefully observed and individuals present counted. In small animals this can be calculated using mark and recapture technique.
            • Capture a sample of animals and mark them in a not harmful way, number captured (c1) Release them and leave traps open again, number captured second time is (c2) The number of marked animals captured on the second time is (c3)
              • Total population = (C1xC2)/C3
                • You can use Simpson's diversity index to calculate  the biodiversity of a habitat.       D = 1-(?(n/N) 2 )         n is the number of individuals of a particular species.  N is the total number of individuals for all the species.
                  • A high value indicates a diverse habitat. Habitat tends to be able to withstand change
                  • A low value indicates a habitat dominated by very few species. A small change could damage or destroy the whole habitat
                  •  current estimates of global biodiversity It is estimated that there are more than 1,730,000 species in the world and 89,000 in the UK. This is not a measure of biodiversity because they do not take into account the number of individuals in each species, or give any indication of the variation between different species, or within a species.
                    • We cannot be sure how accurate they are because They do not include any marine species We cannot be sure that we have found all of the species on earth Evolution and speciation are continuing Many species are endangered and some are becoming extinct
            • Tiny animals in the soil are estimated by taking a sample of soil and sifting through it to find all of the individuals.     Sampling water is a similar process, you use  a net to sample in the body of the water and to sift through the mud at the bottom- from this you can estimate population size and density
    • Sampling: In order to measure the biodiversity of a habitat, you need to observe all the species present ,identify them and count how may individuals of each species there are.
      • This is important as human activities can affect the environment in a variety of ways. Unless we study these affects, we cannot assess the impact this has.  Enviromental impact assessments are very important parts of planning, they are used to estimate effects of a planned development on the environment.
        • .Random sampling means studying a small part of the habitat and assuming it contains  representative set species that can be applied to the whole habitat. The sample sites must be chose at random.
          • Habitat is randomly sampled meaning that random portions are selected and studied in detail, results are then multiplied up to estimate the numbers in the whole habitat
          • There are three ways to randomly select an area: 1.Take samples at regular distances across the habitat. 2. Use random number, generated by a computer or a random number table, to plot coordinates within the habitat. 3.Select coordinates from a map of the area and use a portable global positioning satellite system to find the exact position inside the habitat.
            • Sampling Plants
              • There are two main ways to measure the biodiversity of plants: Random Quadrats and Using a transect
                • Quadrats- a square frame used to define the size of the sample area. Plants within area are identified, you then measure their abundance( the frequency of occurrence  of plants in a sampled area) The abundance is then  measured in one of  three ways:
                  • 1.An Abundance Scale- Each species is given an abundance score, such as ACFOR scale. Not precisely quantative
                  • 2. Percentage cover- The percentage cover of each plant in the quadrat is estimated. Sometimes the quadrat is divided in 100 small squares to help estimates.
                  • 3.Point frame- A frame holding a number of long needles, usually ten, to measure percentage cover. Each plant touching the needle is recorded. Each plant recorded touching the needle will have a 1% cover
                • Transects- A long rope of tape measure is stretched across the habitat, and samples are taken along the line.          - Line transect is where you would record plants touching the line at set intervals along the line  -Interrupted belt transect is where a quadrat is used at set intervals along the line  - Cont. Belt transect is where a quadrat is continuously used along the transect.
            • Sampling animals
              • Problems with sampling animals include: They move- attempt for a sample will disturb the habitat.  Many animals  ( in particular large ones) will notice your present and try to hide.
              • Smaller animals can be trapped, their numbers observed and total population estimated. Larger animals have to be carefully observed and their numbers estimated.
              • Sweep netting- Sweeping a net through vegetation. Any organisms caught are released onto a white sheet and counted. Suitable for low vegetation that is not too woody.
                • Collecting from trees- A white sheet is held under a branch, the branch is knocked so any small animals drop onto the sheet.
                  • Pitfall trap- A container buried in the soil so that its just below the surface. Any animals moving through the plants or leaf litter will fall into the container.  Trap should cont. a little water or scrunched paper to stop the animals getting out, also should be sheltered from rain.
                    • Tullgren Funnel- Leaf litter is placed in a funnel. A light above the leaves drives the animals downwards as the leaf litter dries out and warms up they fall through mesh screen into jar below.
                      • A light trap-      An ultraviolet light attracts insects , which eventually fall into vessel of alcohol below.
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