Plant Sampling Techniques Warning Lab lectures included on

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 • Precision: similarity measurements

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

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!”

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)

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

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

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

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

Focus on Cover • Many ways to get cover (biomass) data: – 6) Trees: DBH (diameter at breast height: 4. 5 ft or 1. 3 m)

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

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

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)

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

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

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

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!

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

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)

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

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

Belt Transect Method • Density of A = 10/40 m 2 = 0. 25/m 2 • Frequency of A = 9/10 = 0. 9 • % Frequency of A = 0. 9 X 100% = 90% 2 m 2 m 4 species: A =red, B= turquoise, etc.

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

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

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:

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)

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

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

Line Intercept Method • Cover: record distances covered by canopies

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

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