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Plant Sampling Techniques

Plant Sampling Techniques. Warning!. Lab lectures included on Lecture Exam #1!. Sampling: Why?. Best answer is 100% sample (count/measure everything) Not practical Ex, describe vegetation Lee County AL. Accuracy vs. Precision. Accuracy : how close samples to

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Plant Sampling Techniques

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  1. Plant Sampling Techniques

  2. Warning! • Lab lectures included on Lecture Exam #1!

  3. Sampling: Why? • Best answer is 100% sample (count/measure everything) • Not practical • Ex, describe vegetation Lee County AL

  4. Accuracy vs. Precision • Accuracy: how close samples to • Precision: similarity measurements

  5. Accuracy vs. Precision • Accuracy: not known unless • Precision: standard error of mean (S) Standard deviation

  6. Sampling • Choosing technique depends on: • 1) Desire for • 2) Objective • 3) Time/money • 4) Tradition! “Without our traditions, our lives would be as shaky as…..a fiddler on the roof!”

  7. Importance • Often: how “important” a plant species is • 3 measures importance (sp. A) • Density of A = No. inds. per unit area (reflects abundance of A) • Frequency of A = No. times sp. A in samples divided by total number samples (reflects pattern of A) • Cover of A = Percent area occupied by A (reflects biomass of A)

  8. Focus on Cover • Many ways to get cover (biomass) data: • 1) harvest & measure biomass • 2) visual estimation • Note canopy edges “filled in” by observer

  9. Focus on Cover • Many ways to get cover (biomass) data: • 1) harvest & measure biomass • 2) visual estimation • 3) point frame

  10. Focus on Cover • Many ways to get cover (biomass) data: • 1) harvest & measure biomass • 2) visual estimation • 3) point frame • 4) moosehorn crown closure estimator

  11. Focus on Cover • Many ways to get cover (biomass) data: • 5) Trees: basal area (area tree trunk per unit area). Bitterlich method.

  12. Focus on Cover • Many ways to get cover (biomass) data: • 6) Trees: DBH (diameter at breast height: 4.5 ft or 1.3 m)

  13. Other Challenges • Clonal plants: density (how determine individual?)

  14. Other Challenges • Clonal plants: density (how determine individual?) • Canopy overlap: where boundaries? • Border calls: in or out? • Solution:

  15. Importance • Often: how “important” a plant species is • 3 measures importance (sp. A) • Density of A = No. inds. per unit area (reflects abundance of A) • Frequency of A = No. times sp. A in samples divided by total number samples (reflects pattern of A) • Cover of A = Percent area occupied by A (reflects biomass of A)

  16. Importance • Calculate Importance Value (IV) • Sum Relative Density, Relative Frequency, and Relative Cover

  17. Importance • Calculate Importance Value (IV) • Sum Relative Density, Relative Frequency, and Relative Cover • IV= Rel. density + Rel. frequency + Rel. cover • <300%= < 100% + < 100% + < 100%

  18. Sample Techniques • 1) Quadrat methods • 2 dimensional sample unit used: quadrat Quadrant?

  19. Quadrat Method • a) Shape? • Oblong better: picks up more variation per sample • But: less perimeter means less in/out decisions (source error) • Compromise: be reasonable!

  20. Quadrat Method • b) Size? • VITAL for determining plant pattern (& important for density measurement) • Can use species-area curve

  21. Quadrat Method • c) Number? • Suggestions include: • A) Sample 1-20% of area • B) Include 95% of species • C) Use Running Mean Graph (Quadrat Sampling Lab #4)

  22. Belt Transect Method • Also 2 dimensional method • Useful dense vegetation • Useful sampling along sharp environmental gradient

  23. Belt Transect Method • Example diagram and calculation of Importance Value of species A 2m 2m Environmental gradient 2m 2m 4 species: A = red, B = turquoise, etc.

  24. Belt Transect Method • Density of A = 10/40m2 = 0.25/m2 • Frequency of A = 9/10 = 0.9 • % Frequency of A = 0.9 X 100% = 90% 2m 2m 4 species: A =red, B= turquoise, etc.

  25. Belt Transect Method • Cover of A: Assume visually estimate covers each species • Values for A: • 10%, 15%, 15%, 10%, 0%, 10%, 5%, 5%, 10%, 10% • Mean cover of A= Sum covers/10 = 9% 2m 2m 4 species: A = red, B = turquoise, etc.

  26. Belt Transect Method Do density, frequency, cover calculations for all other species (B, C, D) 2m 4 species: A = red, B = turquoise, etc.

  27. Belt Transect Method Do density, frequency, cover calculations for all other species (B, C, D) IV= Rel. density + Rel. frequency + Rel. cover For sp. A:

  28. Belt Transect Method Do density, frequency, cover calculations for all other species (B, C, D) IV= Rel. density + Rel. frequency + Rel. cover For sp. A: Rel. density = density of A/density of all species X 100% Rel. frequency = frequency of A/frequency of all species X 100% Rel. cover = cover of A/cover of all species X 100% Calculate IV for other species (B, C, D)

  29. Belt Transect Method IV calculations lab #1 (plotless sampling) + lab #4 (quadrat sampling) Quadrat lab Plotless lab

  30. Line Intercept Method • 1 dimensional method (line has no width) • Useful dense vegetation: scrub Scrub in Australia

  31. Line Intercept Method • Cover: record distances covered by canopies

  32. Line Intercept Method • Cover: record distances covered by canopies • Cover frequency: Divide line into units. Determine frequency of species in units

  33. Line Intercept Method • Cover: record distances along line covered by canopies of species • Density?

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