gettIng readY
Decide what area around your school should
be mapped so that each group surveys a large enough region to include 25–50 trees (if species diversity is high or if overall tree density is low, use a smaller number of trees; if species diver- sity is low or if overall tree density is high, use a larger number of trees).
Using several sheets of graph paper that are
taped together, draw a map that encompasses the entire area that will be surveyed by your class (the number of sheets of graph paper that you use should equal the number of groups so the map can be broken apart to allow each group to complete a part of the overall map; see step 3 below).
Copy Student Page: Tree Species and Location
Data Sheet for each group.
Obtain graph paper and one field guide to
trees of North America (or trees in your specific region) for each group (if you have an area with many ornamental or introduced trees, you may need to create your own field guide). Note: This activity would be much more challenging in the winter when the trees have limited foliage and few, if any, flowers.
doIng tHe actIVItY
1. Ask the student a few questions to generate interest in the topic they will be studying: Why do people plant trees in urban areas?
What do trees provide in urban areas?
To absorb noise pollution, air pollution, and water runoff; to purify air and water; to provide shade; to reduce temperature and reduce wind; to provide habitat and breeding areas for wildlife; etc.
What percentage of a city should trees cover in
order to provide the benefits?
2. Preview the activity with your students so they understand what they will be doing and why their work needs to be accurate.
3. Review the map of the total area that will be surveyed, and point out some landmarks on the map to orient the students. You can then dissemble the pieces of graph paper that make up the survey area so each group has one piece of graph paper to fill in during the tree identification.
4. Introduce the field guides for trees, and show the students examples of the types of trees found in your region. Give them key character- istics to help them identify trees they are likely to see. If your students have never used field guides, you may want to take a class period to practice using dichotomous keys for the trees in your area so your students feel comfortable using the guides and looking for identifying characteristics before sending them out on the mapping project. You can also collect samples of the trees found in your area and send a tagged sample with each group for easy identi- fication. You may choose to invite a U.S. Forest Service educator or local botanist to help your students identify common trees in your area. You may also need to rely on the knowledge and skills of your students who have grown up in the area or who are familiar with the local plants.
5. Give each group its piece of graph paper and point out the size and scale of the map. Clarify that each group’s objective is to find each tree in its portion of the map, then identify and note the location and the species on its piece of graph paper and on the Student Page: Tree Species and Location Data Sheet. If you have the ability, you may want to use a global posi- tioning system (GPS) to locate the latitude and longitude of the trees in your area so they can be positioned precisely. You may want to agree
as a class that only trees exceeding a certain height (e.g., knee-high) will be included or that all trees of any size will be included.
6. Allow the groups to go out into the surround- ing area to begin their survey. Give them a definite time period to return to class with the day’s results, providing enough time to iden- tify difficult trees when they return to class. Ask them to bring back leaves and fruit or a description of any tree that they were unable to identifying with certainty.
7. Before the period ends for the day, go over the results your students have so far, and help them identify tree samples that they have brought to class.
8. Allow your students to continue the survey until they complete all the maps. Ask the groups to go over their data using markers that are dark colors so the maps will be easy to read after they are photocopied.
9. Photocopy the maps created by each group, and give a copy to each student.
10. Ask the students to combine the group maps so they create one composite map.
11. Ask each student to create a complementary map that reveals how the region would be affected if a disease were to wipe out a particu- lar local species. Give each student a different species, or give several students the same spe- cies, depending on the diversity of your area.
12. Ask the students to divide into groups so that each member has created a map that has wiped out a different species. Within the mixed groups, ask your students to take turns sharing their map and describing what the resulting map would look like if that specific species were no longer present.
enrIcHMents
Visit an agricultural field station where plants are
being grown and tested for viability under vari- ous treatments.
Career Connection:
Take a field trip to a genet-
ics lab where students can observe the equip- ment that is used in a working research labora- tory. Invite them to learn about the research questions that are currently being explored at that lab, and encourage them to consider the career options in this field of science.
Students will be introduced to a case study of
the reforestation project in China where fast- growing, nonnative poplar trees were used to stem erosion problems. Because those trees were challenged by insect infestation, a geneti- cally modified poplar was introduced to over- come the obstacle.
Have the students create a field guide for trees
and shrubs in your neighborhood. Each species could be represented on a large index card, and the cards can be hole-punched and placed on a ring clip so they are portable.
Ask the students to research situations where
genetically engineered species of trees were used to (a) combat erosion, (b) provide fire- wood, or (c) solve other cultural or ecological problems (e.g., poplar trees used in China). In the case study, students can be asked to list the positive and negative effects of the biotechno- logical solution and then to describe whether a traditional method would have had greater suc- cess or presented more difficulties.
134 project learning tree Exploring Environmental Issues: BioTechnology ©AmericAn Forest FoundAtion