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% + < 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 2m 2m Environmental gradient 2m 2m 4 species: A = red, B = turquoise, etc.

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.

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.

Belt Transect Method Do density, frequency, cover calculations for all other species (B, C, D) 2m 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) Quadrat lab Plotless 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?