Schedule | Self-Quizzes | Natural History Event | Species List |
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 [USE THE RAW DATA SHEET)
0-1 meters |
5-6 meters |
10-11 meters |
15-16 meters |
20-21 meters |
25-26 meters |
30-31 meters |
35-36 meters |
40-41 meters |
45-46 meters |
EXAMPLE DATA
Species |
Present? Y/N = Frequency |
# Individuals = Density |
Transect Intercept = Cover |
||||||||||||
Triangleleaf Bursage |
Y |
N |
N |
Y |
N |
3 |
0 |
0 |
2 |
0 |
15 |
0 |
0 |
0 |
0 |
N |
Y |
N |
Y |
N |
0 |
5 |
0 |
0 |
0 |
0 |
39 |
0 |
9 |
0 |
Frequency: These data show that triangleleaf bursage occurred in 4 of your 10 plots: the first (0-1 meters), the fourth (15-16 meters), the seventh (30-31 meters), and the ninth (40-41 meters.)
Density: There were 3 individuals in the first plot, 2 individuals in the fourth plot, 5 individuals in the seventh plot, and no individuals in the ninth plot. Note that even though the species was present in the ninth plot, there were no individuals inside the plot – the tree’s branches were hanging over into the plot, but its stem was not more than halfway inside.
Cover: Shadows made by the whitethorn acacia would cover 15 centimeters of the transect in the first plot, none of the transect line in the fourth plot, 39 cm in the seventh plot, and 9 cm in the ninth plot. Note that even though two individuals were inside the fourth plot, none of the branches actually intersected the transect line running down the center of it. Also note that even though there were no individuals present in the ninth plot, the branches hanging over into the plot did intersect the transect line for 9 cm.
PROCEDURE: DATA SUMMARY [USE THE SUMMARY DATA SHEET]
For each species, calculate overall frequency, density and cover. Round density and cover to the nearest tenth (one decimal place.) Then calculate the total density and cover for all species, by adding up values for all species. Finally, calculate the relative density and the relative cover. Again, round to the nearest tenth (one decimal place.)
Frequency = percentage of plots in which the species occurred
Calculate as: # of plots containing the species times 10
Example from above: Frequency of Triangleleaf Bursage = 4 X 10 = 40%. This means that there is a 40% chance that there would be a triangleleaf bursage within any 2 square meter plot.
Density = # individuals counted in the 20 square meters you observed (10 plots each 2 square meters in size)
Calculate as: sum of # of individuals for that species
Example from above: Density for triangleleaf bursage = 3 + 2 + 5 = 10 individuals per 20 square meters
This means that in an average 20 square meters, 10 triangleleaf bursages would occur.
Add densities for all species to get the Total Density.
Cover = % of transect line covered by that species
Calculate as: take the total intercept for the species divided by the 1000 centimeters you examined then multiply by 100.
Example from above: 15 cm + 39 cm + 9 cm = 63 cm/1000cm = 6.3%. This means that 6.3% of the ground is covered by triangleleaf bursage.
Add Cover for all species to get the Total Cover.
Relative Density = % of all individuals that are of that species
Calculate as: Species Density divided by Total of all densities times 100 (round to nearest tenth)
Example from above: Say that a total of 16 individuals of all species were observed (Total Density.) Relative density for triangleleaf bursage = 10/16 = 62.5%. This means that 62.5% of the plants in the area surveyed were triangleleaf bursages.
Total of all Relative Densities = close to 100
Relative Cover = % of all plant cover that is of that species
Calculate as: Species Cover divided by Total of all covers times 100 (round to nearest tenth)
Example from above: Say that the sum of the cover for all species was 260 cm (Total Cover.) Relative Cover for triangleleaf bursage = 63 cm/260 cm = 24.2%. This means that 24.2% of the ground that is covered by plants is covered by triangle leaf bursage.
Total of all Relative Covers = close to 100
Record these data on the Summary Plant Community Data Form (word / pdf) and turn in.