Plant Species Richness: An Ecological Investigation of
Biotic and Abiotic Factors in an Ecosystem
Purpose:
The purpose of this study is to explore field experiment design, to gain observation skills and to compare plant species richness through sampling and sample means.
Background
All processes within ecosystems involve interactions between biotic (living) and abiotic(nonliving) factors. These factors impact what plants grow in an area and how well they grow there. The richness or biodiversity of species in a given area depends on specific habitat characteristics such as available sunlight, precipitation, temperature, soil composition, hydrology and disturbance. Competition from other plants also impacts growth in an area. Species richness can be measured through various sampling techniques and statistics. This study is an introduction to hypothesis construction, experimental samplingin disturbed and undisturbed habitats and sample comparisonsto determine relative biodiversity in three different areas.
Materials:
- 1 square-meter PVC quadrats
- Measuring tapes for transects
- Yard/Meter Sticks
- Group Field Datasheets
Methods
Your group will be working in three sites with different abiotic conditions: a MowedArea Shaded, a Mowed Area Full Sun, and a Field Margin. You will be required to:
1) Create hypotheses relating to the possible effects of various abiotic and biotic factors among the three sites. Please go to the Hypotheses Sheetto do this.
2) Create transacts for sampling the three sites 12 times each with your quadrat. Use the included random number tables to get 48 pairs of random numbers. Use Random Number Table 0-3 to determine how many meters off the transect line you will place your quadrat. Use Random Number Table 0-33 to determine at what foot along the transect you will place your quadrat. Write each set of random numbers in the appropriate spaces on your datasheets.
3) Begin your sampling by placing the quadrat at the appropriate position determined by your first set of random numbers and counting the number of different SPECIES of plantswithin the quadrat. Record this on your datasheet. (You may include the name of a species if you know it). At least 2 people within your group should be counting the number of species in your quadrat so that you get them all. Repeat this for 12 samples in the Mowed AreaShaded, the Mowed Area Full Sun, and the Field Margin.
Special Note: Be especially careful of sampling in the Field Margin as you may encounter Poison Ivy. Stay within the area determined by your Learning Assistant. We have tried to keep you as far away from Poison Ivy as possible, but cannot guarantee its absolute absence in the sampling area. DO NOT TOUCH ANY PLANT WITH THREE LEAVES!
Calculation and Analysis
You will calculate the average number of species found within each area. Students will then compare averages to rank each area according to the average species richness found. Results will be compiled into a lab report to be turned in at the beginning of the next lab session.
Plant Species Richness Hypotheses Sheet
Your group should create hypotheses below as to what you expect to find during this lab regarding number of species in each of the three areas you will investigate.
Example:
“We hypothesize that more plant species will be found in the Mowed Area Shaded than in the Mowed Area Full Sun.”
Group Hypothesis #1:
Group Hypothesis #2
Group Hypothesis #3
You may add additional hypotheses if you wish below:
Mowed AreaShaded
First note possible abiotic and biotic factors present in this area such as: relative temperature, weather last 72 hours, amount of sun and shade climatic factors, soil type, disturbance (none, recurring, occasional), influences from other plants, etc.
SampleNumber / Meters from
Transect
(0-3) / Foot on
Transect
(0-33) / Number of Plant Species Counted
1
2
3
4
5
6
7
8
9
10
11
12
Total number counted (add up lines 1-12) ______
Number of individual plant species found in area
(what is the number of plant species that you listed below) ______
List the plant species found:
Mowed Area Full Sun
First note possible abiotic and biotic factors present in this area such as: relative temperature, weather last 72 hours, amount of sun and shade climatic factors, soil type, disturbance (none, recurring, occasional), influences from other plants, etc.
SampleNumber / Meters from
Transect
(0-3) / Foot on
Transect
(0-33) / Number of Plant Species Counted
1
2
3
4
5
6
7
8
9
10
11
12
Total number counted (add up lines 1-12) ______
Number of individual plant species found in area
(what is the number of plant species that you listed below) ______
List the plant species found:
Field Margin Sample Sheet
First note possible abiotic and biotic factors present in this area such as: relative temperature, weather last 72 hours, amount of sun and shade climatic factors, soil type, disturbance (none, recurring, occasional), influences from other plants, etc.
SampleNumber / Meters from
Transect
(0-3) / Foot on
Transect
(0-33) / Number of Plant Species Counted
1
2
3
4
5
6
7
8
9
10
11
12
Total number counted (add up lines 1-12) ______
Number of individual plant species found in area
(what is the number of plant species that you listed below) ______
List the plant species found: