Setting Up a Study Plot Lab Procedure
To set up a study plot and determine the coverage by native versus non-native (alien) species.
Are there plant invaders in Saguaro National Monument? If so, how much area do they cover?
For the class (to share)
For each team of two students
Marking Off the Plot
1) There will be stakes painted yellow already in place on each side of the Wash. The teacher and a student will tie a string between the stakes. From the yellow stakes, two blue stakes will be place 3 meters north. A string will be tied between the two blue stakes parallel to the first string. Students may begin measuring from the western yellow stake and placing a painted red stake with a number painted on it every 3 meters moving to the east along the string.
2) Tell the teacher what number is on your stake, and be sure she marks her map to show where your plot is.
3) Measure again from the blue stake and mark your two northern corners with rocks.
"Map" the Plot (a.k.a. Collect the Data)
You have a paper with a graph or grid marked on it. Each square on the grid represents 10 cm of the plot. Label each side of the graph with directional labels (north, south, east and west).
4) Select a perennial plant to begin with. Measure from the center of the plant to two sides of the plot with the survey tape or a meter stick. Find this location on your graph. Mark this spot with a small "x". Be careful to orientate the plant correctly on your graph.
5) Measure the diameter of the plant's base (the main stem or bunch of stems that come out of the ground). This is not exact because you cannot reach through the plant to get this measurement. Hold the tape or meter stick above the plant and look down to be as precise as possible when measuring the base size. Draw a circle around the "x" to match this size.
6) Next measure the plant's coverage (the area the plant takes up at its widest point or how much ground is covered by the plant). Draw a circle around the previous circle to show the coverage size.
Note: Your circles may overlap if plants overhang each other. Mark on your map exactly what you see; do not try to fit each plant "nicely" next to one another to make the map look neater.
7) Place a number inside the coverage area to identify this plant. On a separate piece of paper keep a list of the plant number and the name of the plant. If you do not know the name of the plant, write a description of it using the characteristics we talked about in class (leaf shape, size, etc.)
8) Write the coverage measurement next to the name of the plant. This is very important. It will be used later to calculate the percent coverage of native plants versus the coverage by alien plants.
9) Repeat steps 4-8 until all the perennials in the plot have been mapped and identified.
10) All strings must be removed before we leave.
11) Pull out all red and blue stakes. DO NOT REMOVE THE YELLOW STAKES. You and your partner must show me the stake assigned to you BEFORE you may get on the bus to return to school.
12) No trash of any kind may be left. Remember: "A clean park is a happy park!" (-: