Lab 9 Geology and Forest Biodiversity

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University of Arkansas *

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1131

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Geology

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Feb 20, 2024

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LAB 9: GEOLOGY & BIODIVERSITY 100 points Due exactly one week from lab start time. LEARNING OUTCOMES At the end of this lab, you will be able to: 1. Describe how to perform an arboreal survey. 2. Calculate quantitative measures of biodiversity. 3. Discuss environmental and other controls on tree biodiversity. INTRODUCTION For this lab, we will sample tree species composition and productivity in the woodland area behind the Clinton House Museum on the University of Arkansas campus. We will sample a series of 1/100-hectare circular plots (5.64 m radius), the measure the number of trees per hectare (ha), the cross-sectional area of the tree stems per hectare (i.e., basal area), and several other variables (Figure 1). Geology and Biodiversity StoryMap Presentation Figure 1: A) Illustration of a sample plot. A tree must be at least 10 cm in diameter at breast height (DBH) to be included. If at least half of the tree trunk is in the plot, the tree should be included in the analysis. After the data are collected, you will make a series of calculations to determine: 1

- Tree absolute density (number of trees per hectare for all species) - Tree relative density (percent trees per hectare for each species) - Number of tree species encountered on the transect (measures biodiversity) - Basal area per species - Combined basal area for all species - Relative species dominance - Total basal area in m 2 per hectare (measures productivity) These calculations will allow you to make quantitative interpretations about biodiversity on a wild part of campus. Each calculation is described in more detail within the assignment questions. Identifying trees There are several species of trees on campus, but you may not know how to identify them. If you have trouble, please refer to various online resources, a tree ID app, or the book “Trees of Arkansas.” Identify trees to the genus level (Oak, Maple, Ash, etc.). If a species is unidentified, note it as “unknown” in your tables below. 2

LAB 9: GEOLOGY AND BIODIVERSITY Name: _____________________________ Section: _____________________________ Perform the following calculations, show your work, and answer the questions [100 pts]. Part 1: Set up plots In groups, set up four 1/100 hectare plots (one per group) in the wooded area pictured below. For each plot, note the latitude/longitude coordinates of the centroid, then measure 5.64 meters from the centroid to the edge of the circle, and mark the boundaries of the plot. You can use field tape here to help visualize the plot. Figure 1 : Google Earth image of measurement area. 3

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Part 2: Data collection (30 pts) Draw a map of all trees sampled within each plot (e.g., Figure 1), noting DBH and species (or at least genus: do the best you can here). Only indicate those trees 10 cm > DBH. Plot number (your group number): ___________________ Centroid Coordinates (lat and long of your plot’s center point): __________________________ Find north and draw your north arrow here: 4

Part 3: Calculations 1) Stem density : count the total number of trees in each plot, then multiply by 100 to get stems per hectare. Add the total stems per hectare together then divide by 4 (the number of plots) to get the average. [15 pts] Plot 1: Total number of trees: Stems per hectare (total # x’s 100): Plot 2: Total number of trees: Stems per hectare: Plot 3: Total number of trees: Stems per hectare: Plot 4: Total number of trees: Stems per hectare: AVERAGE NUMBER OF STEMS PER HECTARE: 2) Basal area : use the DBH to get basal area for each randomly sampled tree in each plot using the formula for the area of a circle, π(DBH/2) 2 . DBH should be in cm. Basal area will be in cm 2 . [15 pts] PLOT 1 TREE # TREE SPECIES DBH (cm) BASAL AREA (cm 2 ) 5

PLOT 2 TREE # TREE SPECIES DBH (cm) BASAL AREA (cm 2 ) PLOT 3 TREE # TREE SPECIES DBH (cm) BASAL AREA (cm 2 ) PLOT 4 TREE # TREE SPECIES DBH (cm) BASAL AREA (cm 2 ) 6

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3) Relative Frequency : The number of trees per species divided by the total number of trees measured; e.g., 12 shagbark hickories / 30 total trees = 0.40 (decimal form) or 40% (the sum of your percentages should equal 100%). [10 pts] TOTAL # OF TREES (ALL 4 PLOTS) : ___________________ SPECIES TOTAL NUMBER OF TREES FOR THAT SPECIES % FREQUENCY 4) Relative dominance : List the total basal area from each species (found in question 2; you’ll need to add up the basal area for trees of the same species). Which is the most dominant, by percentage (total basal area per species/total basal area of all trees)? [10 pts] SPECIES TOTAL BASAL AREA (cm 2 ) % DOMINANCE Dominant species: 7

Questions 1. [5 pts] What is the exposure of the survey site? How do exposure and slope affect growth and biodiversity in the survey area? 2. [5 pts] Besides exposure and slope, what other factors might influence the types of trees that are growing in the survey area? 8

Lab 9 Geology and Forest Biodiversity

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