Lab 10: Analyzing Campus Trees and North American Ecoregions
Name ___________________________________ Lab Section __________Date __________
Materials and sources that will help you
· Pencil & clip board
· Calculator
· Distance measuring tapes
· Tree diameter (DBH) measuring tapes
· Clinometer
· Internet
Introduction
Think for a moment. How tall is the gingko tree next to Butte Hall? What about its diameter? You probably look at this tree almost every day, but have you ever looked up and seen how tall this tree is? Trees provide shelter for many species as well as protection to humans. If strategically planted, trees provide summertime shade and wintertime sunshine to reduce the energy cost of your home. You can select which species of tree you would like to plant in order to maximize the shade during the summertime.
We are seriously concerned about carbon emissions from various anthropogenic sources. Trees sequester carbon from the atmosphere via photosynthesis. Sequestered carbon will not be released back into the atmosphere until trees are decomposed or burned. A tree’s biomass shows how much carbon has been sequestered, and the height and diameter of a tree are good indicators of the biomass. In this lab, you will determine the height and measure the diameter of three trees on campus. You will also learn that different ecoregions are associated with different amounts of biomass.
Section 1 – Campus Trees Analysis
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Make sure to read the following website before coming to the lab 10. Forest Canopy Heights Across the United States http://earthobservatory.nasa.gov/IOTD/view.php?id=44717
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In this section, you will estimate tree heights and measure DBH (diameter at breast height) values. In order to estimate the height of a tree, you will use a clinometer and a tape measure.
Figure 1: Data required to estimate the height of an object
In order to estimate the height of a tree, you need to measure three values (Figure 1):
E : an observer’s eye height from the ground (in meters);
D : a distance from a tree to the observer (in meters); and
α : the angle of the top of the tree from the observer’s eye height (in degrees).
You will use a tape measure (in meters) for the values of E and D , while you use a clinometer (in degrees) for the value of α .
Additionally, you will use a DBH tape to measure the diameter of a tree at breast height.
“Diameter at breast height, or DBH, is the standard for measuring trees. DBH refers to the tree diameter measured at 4.5 feet above the ground.” See the illustration below (Figure 2) for details.
(https://www.portlandoregon.gov/trees/article/424017)
Figure 2: Measuring height of the DBH value
(https://www.portlandoregon.gov/trees/article/424017)
Form a group of 4-5 members so that there is a total of five groups. Alternatively, you can form a group with members whom you collected temperature data along a designated path (Lab 4).
Before you start collecting data to estimate tree heights, assign one group member who will measure the angle ( α ). Then you will then measure this group member’s eye-level height ( E )—from the ground to this group member’s eye level.
The observer’s eye height ( E ) is _____varies_____ m.
This height ( E ) is probably measured in meters and centimeters. Convert your reading so that this height ( E ) is in meters. For example, if this height ( E ) is 1 meter and 58 cm, then this value in meters is 1.58 m. Remember that 1 m = 100 cm.
1) We will first gather and practice how to estimate tree height and measure a DBH value on the south side of Butte Hall. Your instructor will show you how to set up your devices.
E : an observer’s eye height from the ground: ___varies_______ m
D : a distance from a tree to the observer: _____varies_____ m
α : the angle of the top of the tree from the observer’s eye height: _____varies_____ degrees
2) Calculate the tree height using the data you just collected. You will use the following equation.
Height (in meters) = D x tan(α) + E
Use the calculator on your smartphone to calculate the height of this tree.
The height of this practice tree is: ____varies______ m
3) Now your instructor will show you how to use the DBH tape to measure the tree diameter at breast height.
The diameter at breast height is: ____ varies ______ cm
Circumference at breast height is:_varies __cm. Divide by 100 to find meters:__ varies ______m
4) Go to a designated location and estimate the height and measure the DBH value of a predetermined tree.
| Eye-height (E in meters) | Distance (D in meters) | Angle (α in degrees) | Tree height (m) |
| varies | |||
| DBH (in centimeters) | Circumference (in meters) | Notes | |
| varies |
5) Your group will select one additional nearby tree and repeat this exercise. Use a smartphone and take a picture of the tree (and you will show it to your instructor upon returning to the classroom).
| Eye-height (E in meters) | Distance (D in meters) | Angle (α in degrees) | Tree height (m) |
| varies | |||
| DBH (in centimeters) | Circumference (in meters) | Notes | |
| varies |
6) Report estimated tree heights and measured DBH values.
7) Your instructor will plot the data using Excel to show you the relationship between the tree heights and DBH values. Before DBH and tree heights are plotted, form a hypothesis regarding the relationship between these two values.
For the trees on the CSU Chico campus, as DBH increases, height also increases.
I think this is a positive, linear relationship
8) Is your hypothesis rejected or not rejected? Is it a linear or non-linear relationship? Is it positive or negative relationship?
I was right! Tree height increases as DBH increases in a positive, linear relationship
9) Use the chart provided to determine the amount of carbon (C) in your tree:_________varies________kg
10) Multiply your answer to #9 by 3.6663 to determine the amount of carbon dioxide (CO2) sequestered by your tree over the course of its lifetime:
___________ varies ________________kg
11) A round-trip drive from Chico to Los Angeles in an average car emits about 1030 lbs of carbon dioxide. How does this number compare to the amount of carbon dioxide your tree has sequestered? Do you think that planting trees is the answer to reducing excess carbon dioxide in our atmosphere? Explain.
Apparently, planting trees alone is not the answer to how to remove carbon dioxide from the environment. The amount of CO2 sequestered by a tree in its lifetime can be cancelled out by the CO2 emissions produced by just a few car trips.
Section 2 – Ecoregions and Net Primary Productivity
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Figure 1 – Ecoregions (level 1) of North America
Source: ftp://ftp.epa.gov/wed/ecoregions/cec_na/NA_LEVEL_I.pdf
Figure 2 – NPP of Biomes
Source: http://www.nature.com/scitable/knowledge/library/terrestrial-primary-production-fuel-for-life-17567411
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The Net Primary Productivity (NPP) of any location describes the net photosynthesis taking place. Biomass is a physical representation of that photosynthesis and displays the difference between Gross Primary Productivity (GPP) and NPP. GPP minus respiration by plants is equal to NPP. In other words, NPP represents the amount of stored energy generated by plants, and is measured in terms of how much carbon is “fixed” during the photosynthetic process. NPP can be calculated for any geographic region. It is usually expressed as a rate, such as grams or tons of carbon per hectare per year. Keep in mind that as leaves fall off trees, some of that biomass is being lost to decomposition. Also, a portion of the productivity of plants is found belowground in the form of roots.
Source: http://www.nature.com/scitable/knowledge/library/terrestrial-primary-production-fuel-for-life-17567411
For this exercise, we will be connecting ecoregion types found in the contiguous United States with their associated level of NPP.
1.) In the spaces provided below, complete the following:
· For each of the listed cities, determine that location’s ecoregion by first finding the city using a laptop, phone, or tablet and some kind of mapping app. (Any map app will work, like google maps or apple maps). Next you need to analyze Figure 1 above along with the descriptions of each ecoregion and determine which ecoregion each city falls within.
· Once the location has been found, use the ecoregion packet provided by your instructor to determine the biome listed in Figure 2 in which the ecoregion fits. Use this information to determine that ecoregion’s Net Primary Productivity (NPP) in grams of carbon per hectare per year. (It’s the third column in the table Figure 2)
2.) Does latitude alone determine the ecoregion of a location? What other environmental factors must be considered?
Latitude alone does not determine the ecoregion of a location. Elevation, soil types, and weather
patterns—such as annual precipitation—are also factors in determining the ecoregion of a location.
1.) City: Portland, Oregon
Ecoregion:______Temperate Forest____________
NPP: 465 – 741 gC/ha-1yr
2.) City: Chico, California
Ecoregion:______Temperate Grasslands______
NPP: 129 – 342 gC/ha-1yr
3.) City: Kansas City, Kansas
Ecoregion:_____Croplands______
NPP: 288 – 468 gC/ha-1yr
4.) City: Indianapolis, Indiana
Ecoregion:_____Croplands________
NPP: 288 – 468 gC/ha-1yr
5.) City: Las Vegas, Nevada
Ecoregion:___Desert______________
NPP: 28 – 151 gC/ha-1yr
6.) City: Miami, Florida
Ecoregion:_____Tropical Forest________
NPP: 871 – 1098 gC/ha-1yr
7.) City: Flagstaff, Arizona
Ecoregion:________ Temperate Forest _______
NPP: 465 – 741 gC/ha-1yr
8.) City: Tuscon, Arizona
Ecoregion:_______Desert_______
NPP: 28 – 151 gC/ha-1yr
9.) City: Missoula, Montana
Ecoregion:_____ Temperate Forest ______
NPP: 465 – 741 gC/ha-1yr
10.) City: Montpelier, Vermont
Ecoregion_____ Temperate Forest ______
NPP: 465 – 741 gC/ha-1yr