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Biodiversity

Biodiversity. Average Size. Measure all trees in a transect or quadrat. Produce a size-frequency histogram to show the size distribution. Can also calculate the average size tree. Quadrat Sampling. Randomly select plots and count all individuals in that plot. Each quadrat = 200m 2 .

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Biodiversity

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  1. Biodiversity

  2. Average Size • Measure all trees in a transect or quadrat. • Produce a size-frequency histogram to show the size distribution. • Can also calculate the average size tree.

  3. Quadrat Sampling • Randomly select plots and count all individuals in that plot. • Each quadrat = 200m2. • Can calculate density as #/m2 then multiply by total area to estimate the total # of trees. • 60,703 m2 = 15 acres

  4. Transect Sample • Randomly select a transect of known area and count every tree in that transect. • Each transect = 90m2. • Can calculate density for each tree species. • 60,703 m2 = 15 acres

  5. Measuring Biodiversity • The simplest measure of biodiversity is the number of species – called species richness. • Usually only count resident species, and not accidental or temporary immigrants • Another concept of species diversity is heterogeneity: Heterogeneity is higher in a community where there are more species and when the species are more equally abundant.

  6. Diversity Indices • A mathematical measure of species diversity in a community. • Reveals important information regarding rarity and commonness of species in a community.

  7. H= - pi(lnpi)  Larger H = more diversity Shannon-Wiener Diversity Index (H) • Variables associated with the Shannon-Weiner Diversity index: • S – total number of species in the community (richness) • pi – proportion of S made up of the ith species • Hmax = ln(S) • EH – equitability (evenness; b/t 0 and 1) = H / Hmax

  8. Species richness and equitability affect the Shannon Wiener index.

  9. D= 1 - pi2ranges from 0 to 1 Simpson’s Index • N = total number of individuals • pi = proportion of each species • Simpson’s Index of Diversity = 1 – D • Ranges from 0 to 1  Low to high diversity

  10. Species richness and equitability affect Simpson’s index.

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