Wood to Wheels 2012– Lesson Two (Updated 12/14)

Jenn Coury

Are tree crowns a sustainable source of bioenergy?

Lesson Introduction

Title: Are tree crowns a sustainable source of bioenergy?

Subject/target grade: Scientific Inquiry , 12th

Duration: 90+ minutes

Setting: Classroom

Learning Objectives: o Students will be able to create and analyze a graph from a data table from the findings section

of a simplified scientific article to reach a conclusiono Students will be able to analyze a graph and look for statistical significance in a peer-reviewed

scientific article to reach a conclusiono Students will be able to use the evidence presented in scientific articles to draw a conclusion

regarding the potential use of tree crowns as a sustainable source of bioenergy

Michigan Content Standards: relevant science and math standards that the lesson addresses.

Science High School Content Expectations:B1.1B Evaluate the uncertainties or validity of scientific conclusions using an understanding of sources of measurement error, the challenges of controlling variables, accuracy of data analysis, logic of argument, logic of experimental design, and/or the dependence on underlying assumptions.

B1.1E Describe a reason for a given conclusion using evidence from an investigation.

B1.1g Use empirical evidence to explain and critique the reasoning used to draw a scientific conclusion or explanation.

B1.1h Draw conclusions from data presented in charts or tables.

B1.2C Develop an understanding of a scientific concept by accessing information from multiple sources. Evaluate the scientific accuracy and significance of the information.

B1.2D Evaluate scientific explanations in a peer review process or discussion format.

B1.2f Critique solutions to problems, given criteria and scientific constraints.

B1.2g Identify scientific tradeoffs in design decisions and choose among alternative solutions.

B1.2i Explain the progression of ideas and explanations that leads to science theories that are part of the current

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Next Generation Science Standards:

Eight practices of science and engineering1. Asking questions (for science) and defining problems (for engineering) 2. Developing and using models 3. Planning and carrying out investigations 4. Analyzing and interpreting data 5. Using mathematics and computational thinking 6. Constructing explanations (for science) and designing solutions (for engineering) 7. Engaging in argument from evidence 8. Obtaining, evaluating, and communicating information

Performance ExpectationsHS-LS1-1. Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells.

HS-ETS1-1. Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.

HS-ETS1-2. Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.

HS-ETS1-3. Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.

Common Core State Standards for Math:

Practice 4 – Model with mathematicsS-ID.1. Represent data with plots on the real number line (dot plots, histograms, and box plots).S-ID.3. Interpret differences in shape, center, and spread in the context of the data sets, accounting for possible effects of extreme data points (outliers).S-ID.5. Summarize categorical data for two categories in two-way frequency tables. Interpret relative frequencies in the context of the data (including joint, marginal, and conditional relative frequencies). Recognize possible associations and trends in the data. S-ID.6. Represent data on two quantitative variables on a scatter plot, and describe how the variables are related.

a. Fit a function to the data; use functions fitted to data to solve problems in the context of the data. Use given functions or choose a function suggested by the context. Emphasize linear, quadratic, and exponential models.c. Fit a linear function for a scatter plot that suggests a linear association

S-IC.5. Use data from a randomized experiment to compare two treatments; use simulations to decide if differences between parameters are significant.S-IC.6. Evaluate reports based on data.

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Lesson Background

The Guiding Question: Are tree crowns a sustainable source of bioenergy?

Materials and Equipment Needed: o Class copies of Predicting the Future Energy Benefits of Treeo Class copies of Energy trade-offs between intensive biomass utilization, sit productivity loss, and

ameliorative treatments in loblolly pine plantationso Projector if you would like to project the articles for class discussion at any pointo Science Notebooks

Safety precautions: None.

Advanced Preparation: Make copies, read and answer the questions to familiarize yourself with the content.

Background Information for Teachers: This lesson is designed to introduce students to reading

scientific literature. Students will begin by reading an article that has been simplified from a published, peer-reviewed scientific article. The simplified article is written at a middle school level, but will challenge high school students because they typically have no experience with a scientific format. The questions are designed so students actively analyze data and use that evidence to form conclusions. Next, students will read parts of the original, published peer-reviewed scientific article. The questions once again are focused on evidence and conclusions. The hope is that students gain confidence from the simplified article that they can then use as they read the original article. Reading scientific literature is essential in most science college courses.

Pre-teaching: Information that students need to know to begin exploration. Students should have a working knowledge of scientific inquiry and analyzing evidence to support a conclusion. You may need to define “statistically significant.” Suggested: Lesson One, Introduction to Wood to Wheels.

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Lesson Core

Engage: How will the teacher introduce the question in a way that engages the students’ interest and builds on their prior knowledge? Building on prior knowledge: Questions that the teacher might ask to assess students’ prior knowledge.

o Ask: What things can you think of that might be used as biomass (feedstock for biofuels)? One minute individual write in science notebook. One minute share with a partner. Create a class list on the board (a student volunteer can record). To tie everything together, refer back to slides 3-5 of the Wood-to-Wheels PP in Lesson

One (students may or may not remember, depending on how much time you spent on them – that’s ok, go ahead and explain in a little more detail now)

http://www.bioenergyconsult.com/biomass-feedstock-in-middle-east-and- north-africa-mena/

http://bioconversion.blogspot.com/2007/04/bioconversion-101-biotown- sourcebook.html

http://www1.eere.energy.gov/biomass/m/feedstocks_types.html

Pass out: Predicting the Future Energy Benefits of Tree and corresponding student worksheet

Explore 1: How will the teacher facilitate the students’ exploration of the problem and collection of data. What questions will the teacher ask to guide students in exploration?

o Read the directions aloud with your students: Directions: Read Predicting the Future Energy Benefits of Tree Crowns, which is a simplified scientific article (use the article’s title as your heading). Record the answers to the following questions in COMPLETE SENTENCES in your science notebook. For data questions show your work and label your graphs.

o Explain to the students that their goal is to understand the study that the scientists completed. They will identify the scientists’ questions, analyze the data, and use the evidence to support a conclusion. They will be starting by reading a simplified version of a scientific article, but in the second part they will be reading the original, peer-reviewed scientific article. You will discuss the answers to the questions on the simplified article before moving on to the second article.

Explain 1: How will the students be expected to explain their data or evidence? o As stated in the directions, students should record the answers to the questions in COMPLETE

SENTENCES in their science notebook. If your class does not use science notebooks, lined paper is fine. It is always helpful to date and appropriately entries. For data questions students should show their work and label their graphs. Remind them this helps think through the reasoning behind the math or the graph.

o Questions 9 & 10 really ask the students to explain the evidence as a whole, encourage them to take their time and really use the evidence for these questions.

o As they work, take the opportunity to both read over their shoulders and ask them to verbally explain whatever question they are working on when you come by.

Elaboration 1: How will the teacher facilitate the sharing of student explanations? What questions will the teacher ask to clarify student thinking?

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o When students have completed their reading and science notebook entries, discuss as a class. Options for discussion format –

Assign each group a question, and have them present the answer to the class. Ask each student to circle three questions they feel confident in their answer and would

be willing to share. This usually encourages them to raise their hands when you ask for volunteers.

Do a pair and share if you feel confident your students are mostly on the right track

Pass out: Energy trade-offs between intensive biomass utilization, sit productivity loss, and ameliorative treatments in loblolly pine plantations and corresponding student worksheet.

Explore 2: o Read the directions aloud with your students: Directions: Read the abstract above and the parts

of Energy trade-offs between intensive biomass utilization, sit productivity loss, and ameliorative treatments in loblolly pine plantations as directed below (use the article’s title as your heading). This is the original, peer-reviewed scientific article that Predicting the Future Energy Benefits of Tree Crowns was based on. Record the answers to the following questions in COMPLETE SENTENCES in your science notebook. For data questions show your work and label your graphs.

o Explain to the students that this is the original, peer-reviewed scientific article that Predicting the Future Energy Benefits of Tree Crowns was based on. Many students have never read a peer-reviewed scientific article, and may be overwhelmed at first. Remind them that, like any new skill, it takes practice to be good at reading and understand the evidence presented in the article. Encourage them to work with a partner or small group and to ask as many questions as they need to as they work through the questions. Also remind them that the two articles cover the same concepts and to use what they learned from Predicting the Future Energy Benefits of Tree Crowns to understand Energy trade-offs between intensive biomass utilization, sit productivity loss, and ameliorative treatments in loblolly pine plantations.

Note: The students will only read the parts of the original article that correspond to the part of the experiment covered in the simplified article. Be sure the students are focused in on the right parts of the article (page numbers are noted on the student handout).

o You may choose to read the article’s abstract together aloud as a class before they proceed. You may want to do a “think read” for them. As you read the abstract aloud, also say any thoughts you may have in your head. This helps them see that they need to process the sentences as they go, and that even the teacher doesn’t necessarily understand everything right away! This may feel awkward the first time you try it – the students can also try this when reading with their groups.

Ex: Loblolly pine plantations (I wonder what a loblolly pine looks like – pine plantations are cool with their rows of trees) are the most important source of forest products in the U.S. (I wonder where they grow) and the slash (what’s slash exactly?) remaining after conventional harvest (what does conventional mean?) represents a significant (what defines significant? how much?) Potential source of bioenergy (burned? used for what?).

Explain 2: 5

o As stated in the directions, students should record the answers to the questions in COMPLETE SENTENCES in their science notebook. If your class does not use science notebooks, lined paper is fine. It is always helpful to date and appropriately entries. For data questions students should show their work and label their graphs. Remind them this helps think through the reasoning behind the math or the graph.

o Question 3.4 #9 really asks the students to explain the evidence as a whole, encourage them to take their time and really use the evidence for these questions.

o As they work, take the opportunity to both read over their shoulders and ask them to verbally explain whatever question they are working on when you come by.

Elaboration 2: o When students have completed their reading and science notebook entries, discuss as a class.

You may need to re-explain some of the more complicated concepts even after asking for student volunteers. You may want to be able to project the graphs in the article for explanation purposes.

Evaluate and Lesson Closure: How will the teacher connect the student explanations and bring out the big scientific idea. What questions will the teacher ask to bring the big scientific idea of the lesson? What questions will the teacher ask to assess mastery of the learning objectives?

o Remind students of the scientific question: Are tree crowns a sustainable source of bioenergy?o Ask them how the data in the graphs and article provided evidence to support their conclusiono Discuss how each article presented the evidence and how this helped (or not!) them

understand the concepts

Lesson Extension Assessment Options:

o Grade questions of your choice from the two student worksheets. Suggestion of questions to grade:

Predicting the Future Energy Benefits of Tree Crowns #6 & 7 (Practice 4: Analyzing Data) and 9 & 10 (Practice 8: Communicating Information).

Energy trade-offs between intensive biomass utilization, sit productivity loss, and ameliorative treatments in loblolly pine plantations 3.4 #9 (Practice 8: Communicating Information).

o Exit Slip: Give three pieces of evidence to support or refute the statement “Tree crowns are a sustainable source of bioenergy.

o Write an explanation/conclusion (follow your rubric – see lesson three) using the evidence from both articles for the hypothesis: If whole tree harvesting is implemented, then biomass production will increase significantly.

Resources:

How Now Round Cow? Predicting the Energy Future of Tree Crowns. Natural Inquirer: Bioenergy Edition, Vol. 9, No. 1: 37-46.

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Scott, D. Andrew; Dean, Thomas J. 2006. Energy trade-offs between intensive biomass utilization, site productivity loss, and ameliorative treatments in loblolly pine plantations. Biomass and Bioenergy, Vol. 30: 1001-1010.

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Directions: Read Predicting the Future Energy Benefits of Tree Crowns, which is a simplified scientific article (use the article’s title as your heading). Record the answers to the following questions in COMPLETE SENTENCES in your science notebook. For data questions show your work and label your graphs.

Analysis Questions:1. What question were the scientists asking?2. How much energy is available in one hectare of southern pine forest? In just the crowns? In just the

boles? In all of the southern pine forest? 3. Explain at least two negative consequences of using the crowns for energy.4. Explain the three energy values, including the unit MWh, in Table 1.5. The scientists used information that had been previously calculated by others. For the scientists’

research to be accurate, what do you think they needed to do and how should they feel about this information? In what ways do you or should you do when accessing information over the internet.

6. Sketch the set-ups in the three experimental groups.7. Create a graph showing the data in Table 2. Be sure to think about how to best represent the data

given.8. Place the *, **, ****, and ***** on your graph, and in your OWN WORDS, create a caption to explain

what these numbers mean.9. What conclusion should the scientists make based on their evidence? Be sure to explain! Hint: How

did the scientists calculate the 250.8 MWhha-1 number? Show your work!10. In 10 years, tree crowns might be an important source of energy. Based on this research which of the

experimental plots would you recommend to someone wanting to plant southern pine trees for energy? Why?

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KEY

Directions: Read Predicting the Future Energy Benefits of Tree Crowns, which is a simplified scientific article (use the article’s title as your heading). Record the answers to the following questions in COMPLETE SENTENCES in your science notebook (if you do not keep a science notebook, lined paper is fine). For data questions show your work and label your graphs.

Date, Predicting the Future Energy Benefits of Tree Crowns

Analysis Questions: Student answers should be in complete sentences. Page numbers are referenced if you would like to direct students to a spot in the article to help them get started.

1. Pg. 40 What question were the scientists asking?How much potential wood energy is contained in southern pines when the only the boles are removed? When entire trees are removed? When entire trees are removed and fertilizer is added?

2. Pg. 40 How much energy is available in one hectare of southern pine forest? 968 MWh In just the crowns? 112 MWh In just the boles? 856 MWh In all of the southern pine forest? 36,000,000 ha x 968 MWhha-1 = 34,848,000,000 MWhr (so almost 35 billion MWh)

3. Explain at least two negative consequences of using the crowns for energy.1) Energy required to cut and haul trees. 2) Crowns provide nutrients to the soil when they decompose, so removing them means future trees

have fewer nutrients available.

4. Explain the three energy values, including the unit MWh, in Table 1.1) 5.64 MWh– For very Mg (mass) of forest removed, you get this much energy (Megawatts = 1000

Kilowatts) per hour2) .0021 MWh – The amount of energy used when making, transporting, and applying the nitrogen

fertilizer that is applied (it’s not “free”)3) .022 MWh - The amount of energy used when making, transporting, and applying the phosphorus

fertilizer (it’s not “free”)

5. The scientists used information that had been previously calculated by others. For the scientists’ research to be accurate, what do you think they needed to do and how should they feel about this information? Verify the source; be sure it is peer-reviewed and accepted by the scientific community. In what ways do you or should you do when accessing information over the internet. Consider what the source is, etc.

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6. Sketch the set-ups in the three experimental groups (this is just one interpretation).

7. Create a graph showing the data in Table 2. Be sure to think about how to best represent the data given. A bar graph allows comparison. The key should describe the different types of energy measured. Axes should be labeled with units.

8. Place the *, **, ****, and ***** on your graph, and in your OWN WORDS, create a caption to explain what these numbers mean. These are described in the Key to Table 2 on pg. 44.

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9. Pg. 43 and 44. What conclusion should the scientists make based on their evidence? Be sure to explain! Hint: How did the scientists calculate the 250.8 MWhha-1 number?Adding fertilizer to the plots is worth the energy investment of the fertilizer. When the entire tree is removed, you gain 115 MWhha-1 from the crowns. In 10 years, you gain another 137 MWhha-1 because of the additional fertilizer. The fertilizer “cost” 1.2 MWhha-1. So 115 + 137 – 1.2 = 250.8 MWhha-1. Although the application of fertilizer requires energy, it is much smaller than the energy that is produced by the trees after 10 years.

10. In 10 years, tree crowns might be an important source of energy. Based on this research, which of the experimental plots would you recommend to someone wanting to plant southern pine trees for energy? Why? Harvest the whole tree and use fertilizer, see #9.

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Directions: Read the abstract above and the parts of Energy trade-offs between intensive biomass utilization, sit productivity loss, and ameliorative treatments in loblolly pine plantations as directed below (use the article’s title as your heading). This is the original, peer-reviewed scientific article that Predicting the Future Energy Benefits of Tree Crowns was based on. Record the answers to the following questions in COMPLETE SENTENCES in your science notebook. For data questions show your work and label your graphs.

Read 2.3 Energy Balance (pg. 1004)1. Compare and contrast how the original article presents the data from Table 1 in the simplified article.2. Use the numbers in the original article to calculate the 5.6 MWh shown in Table 1 of the simplified

article.3. What source provided the published energy values used in the original article?

Read 3.2 Biomass response to harvest intensity (pg. 1005 – 1006)4. In your own words, what was the biomass response to the stem-only vs. whole-tree harvest

treatments on the LTSP* sites?5. In your own words, what was the biomass response to the stem-only vs. whole-tree harvest

treatments on the CRiSSSP** sites?6. Figure 2 was created using linear regression analysis, a statistical test that looks for a linear relationship

(a best fit line).a. What is on the x-axis? The y-axis?

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b. What does each of the 20 dots on the graph represent?c. What does the solid line represent?d. What does the dashed line represent?

7. Using the evidence from Figure 2 and the second paragraph on page 1006 – a. In your own words, what was the biomass response to the stem-only vs. whole-tree harvest

treatments on all six (LTSP* and CRiSSP**) sites?b. What does the USDA Forest Service define as a significant reduction in productivity?

i. Explain the 12% statistic. ii. Explain the 19% statistic.

iii. Based on these two numbers, do YOU think there is a statistically significant reduction in productivity? Explain.

iv. What could the authors have added to the graph to help you visualize this? c. Why are the scientists unsure if the productivity declines will continue throughout the end of

the planned rotation (these numbers were measured at 10 years, the planned rotation is 25 -60 years.)

d. What was missing from the ecosystem that had this effect on productivity? How could this be made up? (Think about was added in the experimental groups).

*LTSP sites – USDA Forest Service Long-Term Soil Productivity Sites (pg. 1002 and Fig. 1)**CRiSSSP sites – Cooperative Research in Sustainable Silviculture and Soil Productivity (pg. 1002 and Fig. 1)

Read 3.4 Energy Balance (pg. 1008)8. Compare and contrast the data in Table 5 (original article) and Table 2 (simplified article). What data is

omitted in the simplified article? 9. In your OWN WORDS, using evidence from the articles, explain the statement “The energy required to

ameliorate P deficiencies caused by whole-tree harvesting and control non-crop vegetation with herbicides is almost inconsequential compared to the additional energy produced when these treatments are applied.”

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KEY

Directions: Read the abstract above and the parts of Energy trade-offs between intensive biomass utilization, sit productivity loss, and ameliorative treatments in loblolly pine plantations as directed below (use the article’s title as your heading). This is the original, peer-reviewed scientific article that Predicting the Future Energy Benefits of Tree Crowns was based on. Record the answers to the following questions in COMPLETE SENTENCES in your science notebook (if you do not keep a science notebook, lined paper is fine). For data questions show your work and label your graphs.

Date, Energy trade-offs between intensive biomass utilization, sit productivity loss, and ameliorative treatments in loblolly pine plantations

*Student answers should be in complete sentences. Page numbers are referenced in the student handout if you would like to direct students to a spot in the article to help them get started.

Read 2.3 Energy Balance (pg. 1004)1. Compare and contrast how the original article presents the data from Table 1 in the simplified article.Paragraph vs. table, doesn’t show conversion in the original

2. Use the numbers in the original article to calculate the 5.6 MWh shown in Table 1 of the simplified article.20.3GJ X (.27778MWh) = 5.64 MWh Mg GJ

3. What source provided the published energy values used in the original article?See 13 in the Reference section, pg. 1009.

Read 3.2 Biomass response to harvest intensity (pg. 1005 – 1006)4. In your own words, what was the biomass response to the stem-only vs. whole-tree harvest

treatments on the LTSP* sites?Reduced on 8 of 10 sites. Whole tree harvest reduced productivity (removing crowns removes nutrients, decreases growth)

5. In your own words, what was the biomass response to the stem-only vs. whole-tree harvest treatments on the CRiSSSP** sites?Negative on 7 of 10 sites. Whole tree harvest reduced productivity (removing crowns removes nutrients, decreases growth)

6. Figure 2 was created using linear regression analysis, a statistical test that looks for a linear relationship (a best fit line).

a. What is on the x-axis? The y-axis?x – Biomass following stem-only harvesting (Mg ha-1)y – Biomass following whole-tree harvesting (Mg ha-1)

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b. What does each of the 20 dots on the graph represent?20 replicate blocks from the two sites

c. What does the solid line represent?A 1:1 relationship, used for comparison

d. What does the dashed line represent?A 15% decrease in relative biomass (the USDA Forest Service defines this as a statistically significant decrease, pg. 1006).

7. Using the evidence from Figure 2 and the second paragraph on page 1006 – a. In your own words, what was the biomass response to the stem-only vs. whole-tree harvest

treatments on all six (LTSP* and CRiSSP*) sites?Whole tree harvest reduced productivity (removing crowns removes nutrients, decreases growth)

b. What does the USDA Forest Service define as a significant reduction in productivity? -15%i. Explain the 12% statistic. Uses all data

ii. Explain the 19% statistic. Eliminates an “extraordinary” data point – see paragraph #2)

iii. Based on these two numbers, do YOU think there is a statistically significant reduction in productivity? Explain. Answers may vary – should say close to the 15%. May say no, cannot drop a data point. May say yes, this data point is not representative.

iv. What could the authors have added to the graph to help you visualize this? They could have included a best-fit line showing the 12% and/or 19%.

c. Why are the scientists unsure if the productivity declines will continue throughout the end of the planned rotation (these numbers were measured at 10 years, the planned rotation is 25 -60 years.)Things could change – especially nutrient availability

d. What was missing from the ecosystem that had this effect on productivity? How could this be made up? (Think about was added in the experimental groups).

*LTSP sites – USDA Forest Service Long-Term Soil Productivity Sites (pg. 1002 and Fig. 1)**CRiSSSP sites – Cooperative Research in Sustainable Silviculture and Soil Productivity (pg. 1002 and Fig. 1)

Read 3.4 Energy Balance (pg. 1008)8. Compare and contrast the data in Table 5 (original article) and Table 2 (simplified article). What data is

omitted in the simplified article? Answers may vary; the simplified article does not discuss adding herbicide.

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9. In your OWN WORDS, using evidence from the articles, explain the statement “The energy required to ameliorate (make better) P (phosphorus, a nutrient) deficiencies (not enough) caused by whole-tree harvesting and control non-crop vegetation with herbicides is almost inconsequential (very small) compared to the additional energy produced when these treatments are applied.” The energy required to add fertilizers is very small compared to the energy gained when the trees have the nutrients they need to grow (remember the crowns provide the nutrients, so if they are not there to decompose, then fertilizers help make this up).

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