| Explore | We learned that cankers, new sprouts at the base of the tree, exposed roots, bitten leaves, browning leaves, etc. were all signs of an unhealthy tree. We also learned that 4'6" above the ground is a tree's "breast height". Measuring the circumference and diameter of this height gives us a good general feeling about the tree's contribution to the surrounding area, which we can calculate using an online natural benefits calculator. |
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| Research Question | What are the effects of urbanization on tree growth in different geographical settings? |
| Predictions | Some possible outcomes of our study are (1) since trees have to be trimmed if they are growing around power lines, that decreases the amount of CO2 and sunlight they intake which could results in weaker trees; (2) since tree roots can be destroyed from cracking sidewalks, that could also affect nutrient intake from the soil and result in weaker trees; (3) trees that are in the way of construction are either removed and planted elsewhere or destroyed; (4) air pollution could affect the leaves' ability to take in CO2; (5) trees that are planted in sectioned off areas limit the growth of tree roots due to limited space and nutrients in the soil; (6) since city-managed trees don't often receive much care or water (aside from rain) in general, those trees could be skinnier or weaker since their growth rings won't be as thick; and (7) trees that are weak are more susceptible to tree mortality from causes like disease, fungi, or pests. |
| Experimental Design | We plan to compare trees that are managed by the city versus trees that are privately managed. The variables we will measure and observe include cankers, discolored leaves, and the presence of sap on the tree. The variable that will be kept relatively constant is the DBH of the tree. We will record our data within our lab notebooks. 1) Go outside with your measuring equipment, calculator, and lab notebook. 2) Locate either a tree owned by the city or a tree that is privately grown. 3) Find the DBH (diameter at breast height, 4.5’) of the tree by measuring the circumference of the tree three times, averaging the circumferences, and then dividing by pi. 4) If the DBH of your tree is within 8” - 12”, then note which kind of tree you are measuring (private or city-owned), the three circumference measurements, and final DBH in your lab notebook. 5) Identify and take pictures of any cankers, discolored leaves, or exposed sap on the tree. If a canker is found, note the size of the canker. If discolored leaves are found, note the quantity using the general terms “few,” “some,” and “many.” If exposed sap is found, note the quantity by counting the amount of areas with exposed sap. 6) Repeat steps 2 - 5 until you have data on 5 city-owned trees and 5 privately owned trees. |
| Investigation Theme | TREE |
| Grade Level | High School Students (Grades 9,10,11,12) |
| Teacher Name | Crystal Davis |
| School Name | California Academy of Mathematics and Science |
| Session | Spring 2021 |