The Science of Global Warming

Affect of Global Warming on Plants and Trees - Week 4

To explore how the greenhouse effect may affect and relate to the topic of plants and trees, I would engage my class in the following activities. I will have students identify features on local aerial photographs; aerial photos are available at your local United States Geological Survey (USGS) office or available on-line. [15] Students will look at the aerial photo that corresponds to their home address through terra server and determine the land use of the areas surrounding their home. Using our local aerial photo, the students determine the amount of area that is covered by trees. The easiest way I have found to have the students calculate area on an aerial photo is to use clear plastic or overheads on which the students can trace the outline of the various areas while it is laid upon the aerial photo. Be sure that you explain this before the students start to mark on your aerial photos! Students will then calculate the area that corresponds with this to get a sense of the percentage of land that trees occupy. I will have my students look at the woodlot that is adjacent to the school in an aerial photo to get a sense of scale of the area in which we will be doing our weekly field work in. I will then have my students conduct a vegetation analysis in our woodlot, using the biometry (measuring of living things) sampling protocol. There are a couple methods to collect the biometry measurements, depending upon your sampling location. You can even do the protocol in a grass field if that is all that is available. [16] Students will determine tree height and circumference (great math ties here!), canopy cover, ground cover, and graminoid (grass) biomass. Students in my class will also take tree core samples using an increment bore and if time permits we will discuss the concept of dendrochronology and that scientists can determine higher atmospheric temperatures cause thicker rings in trees. Once students have completed the sampling protocols I will have the students engage in a lab activity to measure the amount of photosynthesis using graphing calculators with CO ₂ probe technology. Students will set up the apparatus that will take CO ₂ measurements over a twenty four hour period. Students will work through the calculations included in the case for planting a tree activity that will calculate the amount of CO ₂ taken in by an individual tree and then expanded to the amount per acre, and ultimately to the amount of CO ₂ that the forested areas can sequester. Lastly, students will retrieve the information from the calculators and graph the results. The calculators can then be hooked to the computers to import the graph to place into a report with some rationale to prove that the plant in the vessel went through both photosynthesis and cellular respiration during the sampling period. I will revisit the prior lesson on CO ₂ sequestering by a tree and discuss how insignificant and temporary tree planting is in reducing the global warming problem.