CAR SEQ
pdf
keyboard_arrow_up
School
Massachusetts Institute of Technology *
*We aren’t endorsed by this school
Course
846J
Subject
Geography
Date
Jan 9, 2024
Type
Pages
8
Uploaded by DrCheetahMaster462
LAB 19: AN INVESTIGATION OF
Carbon Sequestration in Urban Trees
Rhona Roth/shutterstock.com
AP Environmental Science
Lab Manual
STUDENT EDITION
PRIMARY TOPICS TOPIC 1.4 The Carbon Cycle
TOPIC 9.5 Global Climate Change
PRIMARY LEARNING OBJECTIVES STB-4.F Explain how changes in climate, both short- and long-term, impact ecosystems.
ERT-1.D Explain the steps and reservoir interactions in the carbon cycle.
SECONDARY TOPICS TOPIC 5.10 Impacts of Urbanization
TOPIC 5.12 Introduction to Sustainability
TOPIC 5.13 Methods to Reduce Urban Runoff
TOPIC 9.4 Increases in the Greenhouse Gases
SECONDARY LEARNING OBJECTIVES STB-4.E Identify the threats to human health and the environment posed by an increase in greenhouse gases.
EIN-2.M Describe the effects of urbanization on the environment.
STB-1.A Explain the concept of sustainability.
STB-1.B Describe methods for mitigating problems related to urban runoff.
Materials
§
Measuring tape (metric)
§
Meterstick or wooden dowels approximately 1 meter in length
§
Tree identification reference, such as iNaturalist
§
Area with trees
§
Calculator
§
Computer or smartphone with Wi-Fi access
Overview and Purpose
This lab investigation is designed to help you understand the concept of carbon sequestration, the importance of trees and forests for carbon sequestration in populated areas (like cities), and the importance of carbon sequestration on a global scale.
§
You will learn forestry field techniques to enable the measurement of trees with only minimal equipment. You will also use an online tool to determine the amount of carbon sequestered by trees and learn about other economic and ecological benefits of trees in urban areas. §
By the end of the lab
, you will have put the amount of carbon sequestered by trees into context and proposed ways that trees can be used strategically to reduce energy use and reduce heat in urban areas. PRE-LAB ACTIVITY
Examine the following chart and watch the “NASA: A Year in the Life of Earth’s CO
2
” video. It can be found
here
.
FIGURE 1: ANNUAL ENERGY BILL FOR A TYPICAL U.S. SINGLE-
FAMILY HOME
Heating and Cooling
Water Heating
Appliances
Lighting
Electronics
0
10
20
30
40
50
Percent of Bill
Computers, TVs,
and All Small
Appliances
Washer & Dryer, Dishwasher,
Refrigerator, etc.
PRE-LAB QUESTIONS Answer the following questions in your lab notebook after viewing the video and reviewing the graph.
1. Identify the largest category of energy use in a typical U.S. home. 2. Describe how most electricity in the U.S. is generated and how this is related to atmospheric carbon dioxide levels. AP Environmental Science
Lab Manual
Carbon Sequestration in Urban Trees
Lab 19
2
STUDENT EDITION
3. The average amount of electricity consumed per month by a typical U.S. household is approximately 920 kilowatt-hour (kWh). Fossil fuel burning power plants emit approximately 0.56 kg of carbon dioxide per kilowatt-hour of electricity consumed by U.S. households. a. Calculate the average amount of electricity consumed per year by a typical U.S. household. Show your work.
b. How much CO
2 is emitted in one year while generating the electricity for a typical U.S. household, if all of the energy is produced by fossil fuel burning power plants. Show your work
GETTING STARTED QUICKWRITE
Write down your answers to the following question in your lab notebook after you have been given an overview of the lab by your teacher. What factors could affect the rate or amount of carbon sequestration by trees? Carbon sequestration:
Carbon sequestration is a process by which carbon dioxide is transferred from the atmosphere into long-term storage reservoirs. This lab will focus on carbon sequestration by trees, which take up atmospheric carbon dioxide during photosynthesis and store it in their biomass as organic carbon molecules. AP Environmental Science
Lab Manual
Carbon Sequestration in Urban Trees
Lab 19
3
STUDENT EDITION
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Lab Investigation PROCEDURE
Forestry Field Measurements
1. Your teacher will assign you to a team and assign your team the trees you are to measure.
2. To determine your stride length, take 5 strides, or steps, and measure the total distance traveled from toe-to-toe, in centimeters. Repeat this three times and record your data in Table 1. 3. Calculate the average distance traveled in 5 strides and record it in Table 1.
TABLE 1
Distance traveled in 5 strides (cm)
Trial 1
Trial 2
Trial 3
Average
4. Calculate your stride length, in centimeters, using the formula below and record it in Table 2. =
Stride Length
Average Length of 5 Strides
5
5. Work together with your teammates to use a tape measure to determine the height, in centimeters, from the ground to your eyes and record it in Table 2.
TABLE 2
Stride length
Eye height
AP Environmental Science
Lab Manual
Carbon Sequestration in Urban Trees
Lab 19
4
STUDENT EDITION
6. To determine a tree’s height using the stick method. You will need a meterstick, or wooden dowel, slightly longer than your arm.
FIGURE 3: THE STICK METHOD
x
x
a. While grasping the stick in a fist, fully extend your arm horizontally, as if going to shake someone’s hand and raise your fist to eye level. Rest one end of the stick on your cheek (below your eye). Then pivot the stick around the point where you are grasping it in your hand until you are holding the stick vertically. You can mark the appropriate point on the stick (or note the measurement, if using a meterstick), so that you can reproducibly grasp the stick in the same place throughout the activity. You will need to end up holding the stick such that the length of the stick above your fist is equal to the distance between your eye and extended fist, forming a rough isosceles right triangle.
b. Holding the stick vertical, at eye level, and at arm’s length, walk forward or backward until the top of the tree is visually level with the top of the stick when you are looking straight ahead and not tilting your head. See the diagram.
c. From that location, count the number of strides to the tree, and record the data in Table 3. 7. Measure the tree’s circumference (in centimeters) at a height of approximately 1.5 meters from the ground and record it in Table 3.
8. Identify the species of the tree using a reference guide or phone app (such as iNaturalist), assign the tree a number, and record the tree’s number and species in Table 3.
Safety Tip: Watch out for tripping hazards, fire ant mounds, or other hazards that are present in your area.
AP Environmental Science
Lab Manual
Carbon Sequestration in Urban Trees
Lab 19
5
STUDENT EDITION
9. Repeat steps 6(b) -8 for all assigned trees.
TABLE 3 – FIELD DATA
Tree
Number Tree Species
Number of Strides to Tree
Circumference at 1.5 meters (cm)
AP Environmental Science
Lab Manual
Carbon Sequestration in Urban Trees
Lab 19
6
STUDENT EDITION
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
ANALYSIS
Answer the questions below in your lab notebook. 1. Use the equation below to calculate each tree’s height and record them in Table 4. (
)
×
+
=
Number of Strides
Stride Length
Eye Height
Tree Height
2. Go to https://design.itreetools.org/
and follow the link to the i-Tree Design tree benefit calculator. Once on the site, do the following. a. Enter the ZIP code of your school, or, if your class left the area to take measurements, the ZIP code of the area where the measurements were taken.
b. Use the navigation tools to center the area where the trees were located on the map.
c. On step 1 “Draw Structures”, click “No”. d. On step 2 “Place Trees”, after entering the data for a tree, place the tree on the map by dragging the icon to the approximate location of the tree. e. On step 3 “Estimate Benefits”, enter any number between 2–99 and click “Calculate”.
You should get a results page with information and multiple pieces of data based on the characteristics of the tree. After exploring and reading through all of the information and data, record the following in Table 4 for each tree: §
Overall benefits—approximate annual economic value provided by the tree
§
Annual CO
2
sequestered—the amount of CO
2
stored or “locked up” in the tree this year §
Total CO
2
sequestered—the amount of CO
2
stored in the tree during its lifetime to date TABLE 4
Tree Number
Tree Species
Circumference at 1.5 meters (cm)
Height (cm)
Economic Benefits ($)
Annual CO
2
Sequestered (kg)
Total CO
2
Sequestered (kg)
3. After reviewing your results, describe the relationship between tree circumference and the amount of carbon dioxide sequestered. 4. According to the U.S. EPA, the average passenger vehicle emits about 0.4 kg of CO
2
per mile. For the tree you measured that has the highest amount of annual carbon sequestration, calculate the maximum distance, in miles, an average passenger vehicle can drive in one year and have all of its carbon dioxide emissions cancelled out (offset) by the tree.
AP Environmental Science
Lab Manual
Carbon Sequestration in Urban Trees
Lab 19
7
STUDENT EDITION
DISCUSSION AND CONCLUSION
Answer the questions below in your lab notebook.
1. Identify two possible sources of error in the measurements used to determine tree height and describe how each could have contributed to inaccurate results. 2. How might the results of the investigation change with the following modifications? a. The trees are subjected to a drought and rather than being in excellent condition, they are in poor condition. b. The trees were young, with diameters that are 50 percent smaller than mature trees.
3. Propose two different feasible solutions for reducing the carbon footprint around a residence or business that both utilize tree planting strategies. Support each solution by providing additional evidence or knowledge.
CHECK FOR UNDERSTANDING
DEBRIEFING QUESTIONS
Answer the questions below in your lab notebook. 1. As a tree grows, its mass increases. Identify the substances that combine to make up the majority of the tree’s biomass. 2. Trees can improve urban areas by providing benefits other than carbon sequestration. Justify planting urban trees by describing how trees can reduce problems associated with urban runoff.
3. There are more heat-related deaths in the U.S. than deaths related to major weather events like hurricanes and tornadoes. Researchers predict a significant increase in heat-related illnesses and deaths as climate change continues and the urban heat island effect causes cities to warm even faster than rural areas. Explain why planting more trees and maintaining urban forests is critical to protecting urban dwellers from increasing heat risks due to warming caused by:
a. The urban heat island effect
b. Climate change
4. Barred owls help control rodent populations in many urban areas and will nest in cavities or nest boxes in parks and suburban areas with older trees. Barred owl nest boxes should be placed between 6 and 10 meters high in trees. A student with a stride length of 70 cm and an eye height of 152 cm counted 8 strides when determining the height of a tree using the stick method. Make a claim about whether the tree is an appropriate height for a barred owl nest box. Show the work needed to provide the evidence to support your claim.
Your Answers Matter: In order to be successful on the AP Exam, your answers to the free-response questions need to be thorough and detailed. It’s important that your responses include complete thoughts and comprehensive answers. Practicing this now will help you succeed on the AP Exam.
Urban heat island effect: The urban heat island effect is a phenomenon where temperatures in urban areas are higher than in surrounding suburban or rural areas. This is due, in part, to the large number of low albedo roads, parking lots, and buildings that absorb more heat than the ground in natural areas as well as the high density of automobiles and other heat-generating machines and equipment in cities when compared to surrounding areas. A lack of plants, including trees, which naturally moderate temperatures by providing shade and retaining water, also contributes to the urban heat island effect. AP Environmental Science
Lab Manual
Carbon Sequestration in Urban Trees
Lab 19
8
STUDENT EDITION