Determining What Plants Grow in the Prairie

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Researchers want to know what plants grow in a prairie. They cannot count every plant. So, they count the plants in a random sample of square meters called quadrats. This data is summarized and used to describe the total plant population. The more quadrats sampled, the more accurate the description

Because researchers want to compare data from year to year, from season to season, from prairie to prairie, they must collect the quadrat data according to standard procedures. You will be working in a research team of three to four students.

Quadrat Study Procedure

You will need:

• Quadrat tool or 4 meter sticks.
• Data sheets tailored to the plants in your prairie (grid and onsite data collection sheets).
• Metric rulers
• Pencils

1. Randomly select a data collection site.(Use an object like a stick or hat as a random site generator. Toss it over your shoulder. Where it lands marks the lower right corner of the quadrat.)

2. Record your data beginning with the grid sheet. Draw the location of the plants as you see them from above and down below the tall grasses. Use the key on the data collection sheet to label the location of each plant or group of plants on the grid. You can enter more than one plant in a square if a low growing plant has another plant towering over it. Remember each square on the grid represents a .1 x .1 meter or about a 4" by 4" square of prairie.

3. Complete the prairie plants and invasives (weeds) invasivesections on the data collection sheet.
   • Record the number of each plant or category of plants.
     HINT: If you come across a plant that is difficult to count, like grass, measure a smaller square of it with a ruler. Use a square centimeter for really small things. Count the number of plants in the samll square and multiply that number by the number of small squares that make up the bigger one. This is called sampling!

   • Record the percent of the area covered by each plant or category of plants.
     From the grid sheet, count the number of squares that each plant occupies. Remember, each square is equal to 1% coverage. Include the total area each covers, even if other plants are above it. If the total area a plant takes up is less than one square, record it as 0. Don't worry if your total percent coverage is more than 100% because leaves from a taller plant can hover over a smaller plant, occupying the same square in the grid.

   • Count up and record the # of types of prairie plants found and the # of types of invasive forbs and unlisted invasives.