Ecology Lab!



Forest Measurements

FOREST MEASUREMENTS Avon Woods forest is typical of many of the forests that occupy sites in southwestern Ohio, Indiana and Kentucky. A large proportion of the beech-maple forest was cleared during European settlement due to the relatively “rich” soil that lies beneath them. A large proportion of the area once in beech-maple forest is currently under agricultural management. Areas once cleared that have reverted to forest are often dominated by, red oak, white oak and hickory, in addition to American beech and sugar maple. The forest you will examine is a good example of this situation. In today’s exercise we will conduct an assessment of the tree stand (a homogenous patch of forest) at Avon Woods. In doing so we will identify and inventory the basal area of overstory tree species. Basal area is a measure of tree density and is useful for determining the amount of harvestable timber in a forest stand as well as for ecological studies. It may be seen as a summary of the number and the size of trees in a stand. As individual tree basal area is related to tree volume and biomass, stand basal area is related to stand volume and biomass. It is determined by estimating the cross-sectional area of all trees in an area at 1.3 meters above the ground. For our lab, basal area will be expressed as square meters per hectare. For more detailed information on basal area you will need to read the following reprint: Elledge, J. and B. Barlow. 2012. Basal Area: A Measure Made for Management. Alabama Cooperative Extension System. ANR -1371. Pg. 1-6.

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Ecology Lab!



Forest Measurements

FIELD PROCEDURES I. Overstory Sampling 1) We will use the plot measurement method to make our forest stand measurements. In this method we will establish a plot of known area somewhere within the forest stand. All of the trees within this plot will be assessed for data collection. 2) To establish our plot, measure and mark a 15 x 30 m plot (0.045 ha) as directed by your lab instructor. Flags or flagging tape will be used to denote the perimeter of the plot (plot corners and mid-distance locations along the perimeter should be marked). For some lab sections, plot locations/perimeters may already be established and ready for use. 3) Working systematically from one end of the plot to the other, stop at each tree that is > 2m in height to collect the following data on the provided data sheet: a) Tree Identification: Using your class notes or identification guides, identify the tree type. Binoculars are also available to help identify structures in the tall canopy. If unsure confirm with your instructor on the identification. Record the identified taxa. b) Diameter at Breast Height (DBH): As discussed in the pre-reading for the lab, one of the most common measurements in forestry is of the the diameter of the tree stem. This has been standardized so that all diameter measurements are collected at breast height, which is about 1.3 m vertically above ground from the base of the tree. Each person should calibrate this height on their body before measuring trees. We will use a diameter tape measure to collect these data. i)

In this lab we will measure the DBH of each tree that we identify above.

ii) On the data sheet, we will record only those specific tree measurements that are greater than (>) 10 cm DBH. If the tree is < 10 DBH, write in “ 10cm, each person will need to calculate the following from your group’s field data in the excel file: a) the basal area (BA) for each tree (m2) b) the basal area for each tree species (m2) c) the basal area for each tree species per hectare (m2/ha) d) the total stand basal area (m2/ha) e) the relative dominance of each tree species. 4) Here are some pointers on how to calculate the information above: a) The basal area (BA) for each tree (m2): i) In the lab pre-reading, the authors explain what basal area is, how to calculate basal area and how it is used in forestry. They provide the following equation for you to calculate basal area in standard US units (square feet). BA (square feet) = (3.14 / 4*144))* (your DBH value2) OR = 0.005454 * (your DBH value2) where BDH is in inches Many individuals in forestry within the US will use these units; however many other scientists prefer to use the metric system. In our lab we have used the metric system and recorded our DBH measurements in centimeters. To help you calculate the basal area (BA) of each tree we have provided you with an equation that will convert your diameter measurement (in cm) to a basal area measurement (in m2). To calculate this, here is the equation: BA (m2) = 0.00007854 * (your DBH value2) All you need to do is put in the DBH value in centimeters into the equation and resulting BA will be in square meters. You will want to calculate the basal area (BA) for each tree. b)

The basal area for each tree species (m2) i) Next you will want to sum the basal area for all similar species.

c) The basal area for each tree species per hectare (m2/ha) i) Next take the basal area for each tree species and convert to m2/hectare. Our plot size was 15 * 30 m, which equals 0.045 ha (hectares). d) The total stand basal area (m2/ha) 4

Ecology Lab!

i)



Forest Measurements

Now sum the basal area calculations for all tree species per hectare to obtain a single value representing the total basal area of the stand.

e) The relative dominance of each tree species i) Finally you will calculate the relative dominance of each overstory species using the following formula. Relative dominance = Total Basal Area of a species x 100 Total Basal Area of all species 5) In excel, each person should compile a summary worksheet that includes all of of their plot data including the original raw data, all tree calculations (described above in 1-4), all densitometer readings and any other collected data (e.g., description of soil texture and pH if collected). You will submit this Excel file (that has the calculations in it) to your instructor. This file does not have to be formatted for printing. It can be basic. We want to see that you have calculated the basal areas correctly. Everyone should know how to complete the calculations on his or her own. I. Assignment To Be Submitted (this should be done individually in a Word document) The following tasks/questions should be completed and submitted for this assignment grade. Make sure you have thoughtful answers to each of the questions below. Each student should write and hand in his or her own answers to these questions. 1) On your own, each student should make a nicely-formatted WORD table that summarizes the basal area of each tree species, the relative dominance of each species, and total stand basal area. This is expected to be your own work. 2) In a couple of sentences describe the results from your data collection. How would you describe the tree stand at Avon Woods (use all data including tree and densitometer information). 3) How do you think this forest has changed over the last 200 years? Would it look substantially different before European colonization? How might it look different? 4) In your opinion is this portion of Avon Woods healthy? What evidence do you have to support this? Is there additional information that would be useful to help you reach a conclusion? What factors do you think foresters and ecologists might use to determine forest health? 5) Based on the basal areas of the species you measured and the composition of saplings, what do you think is the future of this forest? In 100 years will there be a similar composition of adult trees or is the forest in transition? Why? 6) What was the topography of the area surrounding the forest plot? How might this influence other abiotic or biotic factors important for plants at this site? 7) Submit your Excel and Word documents to your instructor. Your instructor will specify how to submit the assignment (e.g., hard copy, email, canvas). This assignment is due by _______________________________________.

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