Since 2010 Trinity ENVS 149 students have made measurement of tree diameter (Using DBH method) and estimates of tree height using a pace and inclinometer technique on trees around McCook Hall. These measurements are useful in forestry to quickly obtain data on individual trees. The methods are not perfect but over a long period of time they can be quite useful to evaluate the growth of trees. This lab will be part of a long term project that has tracked the growth of trees. The past data is sometimes messy. So after the field work portion of the lab, the data mining and presentation (Once again using MS Excel) portion of this lab is equally important. All of your team’s data will be compiled in a master Google Docs spreadsheet. Your data plus past classes’ data will be used to construct graphs of tree grown.
a) Measuring Tree Circumference, Diameter and RadiusUsing a tape measure you will measure the DBH in centimeters. See link on DBH (above) for full explanation). The tapes used can measure either circumference or diameter. Diameter and radii can always be calculated from the circumference or vice-versa. All measurements should be taken on the trunk immediately above the tag. Take multiple measurements by removing the tape and then re-measure. Having different people in your group take measurements will also help ensure repeatable results. |
b) Calculating tree height using pace and an inclinometerTo estimate the height of the trees we will first calculate the length of your pace. To do this, you will lay out a tape measure and count the number of paces it takes you to walk the distance of the tape. You should do at least three trials and take the average number of paces. A pace is defined as two steps. So if you start with your left foot then you count “one” when you step with your right foot. Your gait should be natural and not exaggerated. Once you have the number of paces determined for a set distance you can calculate how many meters 1 pace is for you.
Once your pace has been determined, start with your back to the tree and walk a distance away from the tree that is approximately 1.5 to 2 times longer than the perceived height of the tree. Count your paces as you go. Make sure you end your pace at a location where you can see the top of the tree. From this point, you will use an inclinometer to measure the angle between horizontal and the top of the tree. With the angle and pace (converted to meters), the height of the tree can be calculated using a simple trigonometric function.
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Data needed to complete lab:
Note the 1998 data is from an original tree survey conducted by Trinity College. The units are different and since there is only one measurement for each tree you won’t be able to construct error bars for this year. All other years there will be sufficient data for most trees. However, not every tree has been measured every year so you may have dig through each year to find the necessary data to complete your graphs. YOU DO NOT HAVE TO GRAPH EVERY YEAR. Just 1998, the current year and two years between 1998 and the current
Campus_Trees_1998
Campus_Trees_2010
Campus_trees_2011
Campus_Trees_2012
Campus_Trees_2013
Campus_Trees_2014
Campus_Trees_2015
Campus Trees 2016
Campus Trees 2017
Campus_Trees_2018
Campus_Trees_2019
Campus_Trees_2020
Campus_Trees_2022
Campus_Trees_2023
Campus_Trees_2024
Example of graphs that you need to make: Campus trees_manipulated_example