Name: Block: Due Date: Forest Ecology Lab

Transcription

1 Name: Block: Due Date: Forest Ecology Lab Background Forests are important ecosystems. In this laboratory exercise, you will be simulating the methods used by forestry scientists in determining the tree density, dominance, and frequency. Each of these forest variables tells you something slightly different about the makeup of the forest. In this exercise, you will come to learn what each of these different values tells you about the forest. Objectives You should understand what forest data is used to determine tree density, dominance, and frequency, as well as understand the importance of each of these measures in determining the ecology of the forest. Materials: Forest

2 Materials: Basal Area & Species Data Sample 1 Sample 2 Sample 3 Sample 4 NE Basal Area (ft 2 ) Species Hickory Red Oak Red Bud Red Oak SE SW Basal Area (ft 2 ) Species Red Bud Red Oak Burr Oak Hickory Basal Area (ft 2 ) Species Burr Oak Hickory Red Oak Red Oak NW Basal Area (ft 2 ) Species Red Oak Red Oak Burr Oak Red Oak Procedure: Forest 1. In order to estimate the tree density in the forest given, you will be simulating a standard method called the Point Quarter Method. Before applying this method, we need to identify random points within the forest from which data will be collected. Locate the following points using the values given below and identify each point by making a small dot within the forest picture provided. For example, for sample point 1, measure over 4.5 centimeters using the scale on the bottom of the forest, and measure up 3.0 centimeters using the scale on the left side of the forest. Draw a dot where these two measures converge in the forest. Horizontal Distance (from left side of forest) Vertical Distance (from bottom of forest) Sample Point cm 3.0 cm Sample Point cm 2.0 cm Sample Point 3 11 cm 8.5 cm Sample Point 4 3 cm 8.0 cm

3 2. After finding each of the sample points, imagine two lines traveling through each point, a vertical north-south line and a horizontal east-west line. These two lines would break the area surrounding each point into four quadrants, a northeast quadrant (NE), southeast quadrant (SE), southwest quadrant (SW), and northwest quadrant (NW). Hopefully you now understand why they call it the Point Quarter Method. It might be beneficial for you to lightly sketch in these imaginary lines through each sample point. 3. Next, measure the distance in meters (one centimeter equals one meter) to the nearest tenth of a meter from each sample point to the nearest trees in each of the four quadrants surrounding it. Record the measurements in meters in the data table provided in question 1 on the next page. For example, you may measure the distance from sample point 1 to the nearest tree in the NE quadrant as 1.5 centimeters. You would convert this to 1.5 meters and record it in the data table under sample 1, NE quadrant. 4. Next, determine the average distance from sample points to the nearest tree in each quadrant by adding each of the distance measurements in the data table in question 1 and the dividing by 16 (the total number of measurements). Record this value in the appropriate space below the data table in question 1 on the next page. 5. Next, to determine the average open area surrounding each tree in the forest in square feet, 1) square the value determined in step 4, and then 2) multiply the value determined by 10.6 (there are 10.6 ft 2 per square meter). Record this value in the appropriate space below the data table in question 1 on the next page. 6. Finally, to determine the tree density in acres, plug in the value calculated in step 5 in the following equation. Record this final tree density in trees per acre in the appropriate space below the data table in question 1 on the next page. 7. Answer question 2 on the next page. Procedure: Basal Area & Species Data 43,560 ft 2 / average open area in ft 2 = Density of Trees per acre 1. The Point Quarter Method is used to determine more than an estimate of the density of trees in a forest. It is also used to determine tree dominance and tree frequency. Tree dominance is determined by adding up the basal area values for each species of tree in the samples taken. Since we are simulating this laboratory exercise this data is given to you in the Basal Area & Species Data Table in the materials section. Use this data, determine the total basal area for each tree species and record it in the table provided in question 4 on the next page. 2. So that you know how the values in the table were calculated, determine the basal area in square feet of the log at the front of the class, and record the value in question 5 on the next page. 1) Measure the circumference of the log in feet to the nearest tenth of a foot (1 foot 6 inches would equal 1.5 feet). 2) Use the following formula to determine the basal area in square feet. 3. Answer question 6 on the next page. Area circle = π (circumference / 2π) 2 4. To determine the tree frequency, determine the number of individuals for a given species and divide that number by the 16 (the total number of trees in the sample). To express your value as a percentage multiple your value by 100%. Determine the tree frequency for each tree species and record it in the table provided in question 7 on the next page. Your percentages should add up to 100%. 5. Answer question 8 on the next page.

4 Forest Ecology Lab Questions 1. Distance Measurements Data Table Distance Measurements (cm) Quadrant Sample 1 Sample 2 Sample 3 Sample 4 NE SE SW NW Average Distance = meters Average Open Area = square feet Tree Density = trees / acre 2. What does the tree density tell you about a forest? What would be different about forests having a lesser or greater tree density? 3. Do you think old growth forests may have a different density than young forests? Explain.

5 4. Tree Dominance Data Table Total Basal Area (square feet) Burr Oak Red Oak Hickory Red Bud 5. Basal Area = square feet 6. Based on the Basal Area Data for each species which species would you consider to be the most dominant species? The least dominant species? Explain. 7. Tree Frequency Data Table Burr Oak Red Oak Hickory Red Bud Frequency (as a percentage) 8. Based on the Tree Frequency Data for each species, which species do you consider to be the most dominant species? The least dominant species? Explain.