Climate Change Lesson 10 : Ecosystem Relationships
1. Geographic Ranges
Share with students the following information: The geographic range (Slide 2) of a plant or animal species is an indication of its environmental “preferences,” the conditions that it finds ideal, acceptable, or intolerable. If the climate changes, therefore, it is reasonable to expect that plant and animal species might “move” to occupy different places. The big question is: “What species will move, and where will they go?”
The ecological habitat (Slide 3) of a plant or animal species is the complete set of environmental conditions in the place where the species does well – normal temperature, temperature extremes, wind speed, moisture availability, soil quality, slope, insects, diseases, and so forth. Many of the minor terrain and soil features are not apparent on maps that show an entire state or country – on that kind of map, the broad gradients of temperature and precipitation appear to be the major controls on where a particular kind of plant can grow. This allows us to make fairly simple diagrams of ecological habitats.
Use Ecological Habitat Diagrams transparency (1) or Ecosystem Relationships PPT (Slide 4) Explain that the dark area on each diagram shows the average annual temperature and precipitation (rain plus snow) in the places where a particular tree species seems to grow best. The lighter shading indicates the temperatures and precipitation in all places where the tree is able to grow naturally. The dashed line indicates the complete range of natural environments found in the lower 48 United States. In general, the country has no places that have any combination of average annual temperature and total annual precipitation that falls outside of this line. The “M” on the diagram shows Michigan (Detroit is near the top of the “M” and the Upper Peninsula is near the bottom).
• What is the average temperature range for the entire continental United States? (0o to 70o F.)
• What is the range of precipitation? (0 inches to well over 100 inches)
An ecological habitat is the set of environmental conditions where a given kind of plant or animal lives. Different plants and animals usually have different habitat requirements. That is why theygrow in different places. This graph (Slide 5) shows the climatic habitat of the American Elm. This tree species grows well in places that have average temperatures between 35 and 65 degrees Fahrenheit. It needs 15-30 inches of rain in cool places and 30-50 inches in warmer places.
Distribute Matching Tree Species with Ecological Habitat Diagrams student activity. Have students read the brief tree descriptions and try to identify the diagram that describes each tree species. (See Matching Tree Species with Ecological Habitat Diagrams transparency
2). Answers can be found on Slides 6-7. If needed, distribute Background about Tree Species in the Eastern United States student resource. (This is not an end in itself; it is simply the background needed to ask some important questions about future resources for the Michigan economy.) Discuss student answers, including #7. (Slide 8)
2. Future Ranges
The United States Forest Service tries to predict the future ranges of tree species by combining information about predicted future climate patterns with information about the present climate conditions in places where the tree grows well. Show students Predicting the Future Ranges of Important Tree Species transparency 3 or Slide 9.
The map on the left is the present range of the sugar maple tree. The map on the right is the predicted range in 2100. Note: the prediction is based on the climatic pattern (climate change), not on other possible factors like human land use or ability of a tree to migrate. The original area will not support these species by 2100, but there is no guarantee that trees will migrate to areas that would support growth.
• Sugar maples are colorful and valuable trees. How can the present range of the sugar maple be described? (the sugar maple is common in Appalachia, New England and around the Great Lakes)
• Where might it survive by 2100? (only in a few cold places like northern New England and the Upper Peninsula of Michigan)
Show Predicting the Future Ranges of Important Tree Species transparency 3 or Slide 10 (Loblolly pines – tall, straight trees that are very important for lumber) and ask:
• How can the present range of the loblolly pine be described? (They grow in warm and rainy environments of the Southeastern states)
• Where might it survive by 2100? (It may be able to grow several hundred miles farther north in Tennessee, Kentucky, Virginia, and even Delaware and New Jersey)
Show Predicting the Future Ranges of Important Tree Species transparency 4 or Slide 11 (Paper Birch). Tell students these were an important resource for Native Americans. They used the thin but strong bark of these trees to make house roofs, carrying baskets, and canoes. Ask:
• Where do these trees grow at present? (In northern Minnesota and New England and around the coast of Lake Huron)
• Where might they grow in the future? (somewhere north of Michigan)
Give students Predicting the Future Ranges of Important Tree Species student activity. Instruct them to use the tree descriptions, the maps, and deductive reasoning to describe the range at the present time and in the year 2100 for 4 more common trees. The maps are easier to read in color; these are available on the PPT (Slides 12- 15) or as color transparencies 5-6.
3. Examine projections from models.
Students will look at the distribution of tree species in Michigan, preferably ones found within their own community, and examine how climate change may impact them. The activity is designed to be completed in a computer lab setting. For this activity, each pair of students will need a copy of the Model Projections student activity.
Have students access the United States Department of Agriculture Forest Service website for Climate Change Tree and Bird Atlases using the online instruction and question sheet. Students will be instructed to watch a short introduction video about the tree and bird atlases and their capabilities and application. The video will require sound, so if headphones or audio are not available for all students within the computer lab, teachers should have students watch the video as a class before going to the computer lab to complete the remainder of the activity.
Students will then access the Michigan’s Natural Features Inventory website to locate the land cover change map for their county. They will focus on how their tree species might have been impacted by land use change. Instructions for this are in the Model Projections student activity.
4. Tying it all together.
Using the Forest Service Website (http://www.nrs.fs.fed.us/atlas/tree/ ) try to identify what trees might invade Michigan and become important in the future forest. You might start by noting that bur oak, cottonwood, hickory and Virginia pine are common in some states that are warmer and drier than Michigan.
Write a brief press release to summarize your findings. Your press release should start with a brief description of the present-day forest in your county. You might also include a statement about the importance of the forest for lumber, paper, watershed protection or scenery in your county. Then describe the changes that are predicted by the Forest Service, if the climate changes in the way that is predicted by one or more of the best current prediction models. Note especially if the forest becomes more or less useful economically, because this is where climate change might affect jobs in your county.