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CHAPTER 6: BIODIVERSITY ASSESSMENT (Species richness and species diversity…

- - - -  Simpson’s Diversity Index (D) – based on the probability of two specimens belonging to the same species.
      - • Σ = sum of
        
        • Pi= the proportion of individuals belonging to species i
        
        Pi = no. of individuals in species i/total no. of individuals
        
        • S=no. of species
      - Ranges from 0 (low diversity) to a close 1 (a max of 1 – 1/s) (high density)
      - The index gives relatively little weight to rare species and more weight to common species.
- - - - Determined by the size and shape of the plants rather than species diversity.
        
        Takes into account these characteristics: Height of the tallest vegetation present. (can vary from tall forests) & the projective foliage cover of the tallest level (or stratum) of vegetation. (Projective foliage is the percentage of the ground below the stratum that is covered by the foliage of the plants in the stratum.)
        
        A classification of Australian Vegetation based on these characteristics can give a good measure of the biodiversity of an area.
- - - - Hypothesis 1: Null hypothesis (H0)
        
        There is no difference between the two conditions
      - Hypothesis 2: The Alternative Hypothesis (H1)
        
        There is a difference between the conditions
      - A statistical test (t-test) applied to data to test the difference between the conditions.
        
        If there is a significant difference between the conditions, the null hypothesis is rejected and the alternative hypothesis is accepted.
        
        If there is no significant difference: reject alternative hypothesis and accept the null hypothesis.
        
        The testing only tells us if there is a difference between the conditions. it does not tell us what caused the difference. (could be affected by another factor - so it is important to have a control group)
        
        The statistical power of an analysis is defined when we have confidence in detecting a particular effect, if it exists. Determined by the design of the program and depends on factors (e.g sample size, variability of the data and measurement made).
        
        Environment management involves an evaluation of the costs and benefits of any proposal.