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last
updated
12/1/08
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BIO109
Online
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PLANT COMMUNITY STUDY
OBJECTIVES:
1. To obtain experience in natural history field research
and techniques.
2. To identify many of the plant species occuring here.
3. To better understand the composition of our local flora.
PROCEDURE: Quadrat Sampling Technique
EXAMPLE DATA: these data show that triangleleaf bursage occurred in 4 of your 10 plots, that there were 3 individuals in the first plot, 2 individuals in the fourth plot, 5 individuals in the seventh plot, and 1 individual in the ninth plot, and that shadows made by the triangleleaf bursage would cover 15 centimeters of the transect in the first plot, 24 cm in the fourth plot, 39 cm in the seventh plot, and none of the transect line in the nineth plot. Etcetera for the other species.
| Species | Plots | # Individuals | Transect Intercept |
| Triangleleaf Bursage | 3+2+5+1 | 15+24+39+0 | |
| Creosote Bush | l l l | 1+2+1 | 75+4+82 |
| Whitethorn Acacia | l | 1 | 21 |
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TOTALS
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16 | 260 |
SUMMARY DATA:
For each species, calculate absolute and relative values of each of the following: density, frequency (not relative frequency), and cover. Round all numbers to nearest tenth (except frequecies).
Density = # individuals counted in the 20 square
meters you observed (10 plots each 2 square meters in size)
Example from above:
Density for triangleleaf bursage = 11 individuals per 20 square meters
This means that
in an average 20 square meter plot, 11 triangleleaf bursages would occur.
Relative Density = take
the density of a species divide by the total density of all species then multiply
by 100.
Example from above:
Relative density for triangleleaf bursage = 11/16 = 68.8%
This means that
68.8% of the plants in the area surveyed were triangleleaf bursages.
Frequency = percentage of plots in which the species
occurred
Example from above:
Frequency for triangleleaf bursage = 4/10 = 40%
This means that
there is a 40% chance that there would be a triangleleaf bursage in any 2 square
meter plot.
Cover = take the total intercept for the species
divided by the 1000 centimeters you examined then multiply by 100.
Example from above:
78 cm/1000cm = 7.8%
This means that
7.8% of the ground is covered by triangle leaf bursage.
Relative Cover = take the
cover of a species and divide by the total cover of all species then multiply
by 100.
Example from above:
Relative Cover for triangleleaf bursage = 78 cm/260 cm = 30%
This means that
30% of the ground that is covered by plants is covered by triangle leaf bursage.
Record
these data on the Summary Plant Community Data Form (html
/ word) and turn
in.