| Explore | From outside learning, we’ve learned that plants can also get infected by various diseases, like humans. However, how the plant defends itself, either physically or chemically, may vary compared to humans. Trees, specifically, can be subject to several issues. By taking a couple of Nature Walks outside, it’s evident that many trees can have abnormalities such as cankers, superficial roots, discoloration, or lack of leaves! These issues in trees can be due to invasive species, pests, the weather, or even, human actions. [Some of our observations for the week] Many different species of trees account for different characteristics. Observed trees had both abiotic (exposed roots that likely got hit with the lawn mower blade; broken branches from lightening or storms, etc.) and biotic (cankers on the trunk, or spots, blights, blotches on petals or leaves) characteristics depending on its environment. For example, many of the trees that we observed had discoloration in their leaves. We also noticed some other features on the trees such as cankers and galls. Additionally, using the benefit calculator, we noticed that trees benefit storm water, property value, energy, air quality, and CO2 (some more than others). [Regarding possible research ideas] Some topics we are interested in learning more about is how the tree may defend itself against invasive species? Is there a chemical released perhaps that makes the pest go far away? Something we wondered when looking outside was: why does one tree on a neighborhood block appear significantly malnourished compared to other trees of the same species on the same block? What characteristic of trees makes invasive species more attracted to certain trees than others? |
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| Research Question | Our potential research question is: What effect does the location of a tree in a single family home's backyard have on its growth and noticeable health? | [How did we come up with the question?] Each of us noticed how our trees were located in different areas of our backyards. In one yard, the main tree was located right in the center of the yard while in the other yards, it was located around the perimeter wall/fence. Hence, this led to us wondering about how these differing locations may either improve and impair a tree's health. | [How does the question fit what we know about the topic?]: Regarding tree health, we know that trees are susceptible to various injuries and hazards. Physical hazards may include cankers, leaves falling, discoloration, and more. Additionally, we know that the trees and the roots or trunk have to grow appropriately depending on their location. For example, a tree grown on the slope of a hill will have its roots and trunk positioned differently than a tree grown on a flat surface. Therefore, we were curious whether a tree grown near the perimeter of a yard or in the center (without obstruction) has a significant influence.| [Qualitative/Quantitative Date we plan to collect]: Number of leaves that fell off, Number of discolored leaves, Number of "improved leaves in color", Number of cankers, Amount of fallen tree bark, Overall Texture, Relative strength and health perceived by the human, Overall coloration of the leaves, Level of root growth, and finally, the relative location of the tree in the yard. |
| Predictions | [What are the possible outcomes of our study given the variables we are working with?] (INDEPENDENT VAR. #1) Tree located on the perimeter/edge of a yard (against a wall): Sun/shade % for each tree - more shade, less direct sunlight, impairing its growth to some extent; % of leaves that fall off - higher % of leaves will fall off (measured relatively to the amount of leaves that had fallen on the first day); % of discolored leaves - higher % of leaves that are discolored; % of improved colored leaves - lower; % of leaves with improved color (measured by their overall noticeable vibrancy); Number of cankers - higher number of cankers on this tree; Overall noticeable strength and health - qualitative, might see more stunted growth, irregular growth direction, weak stability. | (INDEPENDENT VAR. #2) Tree located in the center of a yard (no solid structure around it): Sun/shade % for each tree - much more exposure to direct sunlight, thus allowing it grow faster; % of leaves that fall off - lower; % of leaves will fall off (measured relatively to the amount of leaves that had fallen on the first day); % of discolored leaves - lower % of leaves that are discolored; % of improved colored leaves - higher % of leaves with improved color (measured by their overall noticeable vibrancy); Number of cankers - less cankers on this tree; Overall noticeable strength and health - qualitative, consistent growth, regular growth direction, better stability | [What is our explanation for why and how we think this will happen?] (#1) A possible explanation for more leaves falling off is a lack of sunlight and increased shade. The leaves would no longer be needed to convert the sunlight to usable material if there is not access to enough sunlight. We predict this is likely for a tree residing on the perimeter of the yard. (#2) Possible reasons for increased discoloration of leaves on a tree include a lack of sunlight, water and nutrients, poor soil conditions, and compacted roots. Especially in the perimeter of a yard, where more trees are adjacent, we predict the roots to be compacted and soil to not have the best growing conditions. A tree in the center of the yard, however, may have access to more space and sunlight. That could lead to a greater % of colored leaves. (#3) Cankers are a common issue in several trees. A major causing factor of cankers is infection (bacterial or fungal). However, it would be hard for us to observe whether there are any bacterial or fungal species near our trees. So, we would look for other possible factors that result in cankers like poor nutrition, and environment conditions. We predict the trees on the perimeter of the yard to have more cankers because they are in constant competition with trees next to them. (#4) In general, we predict that the tree in the center of a yard will be noticeably stronger, sturdier, and healthier. A major contributor to this would be the fact that the central tree is likely to be by itself; it won’t be competing much with other trees and plants. Additionally, there is definitely more growing space for a central tree, compared to a tree on the outskirts which may be restricted by a house wall or fence. A side wall or fence may make the tree grow abnormally. | [Please Note]: We do understand that we are comparing two different trees in this experiment and that can be confounding. However, we believe that the dependent variables we will be measuring (quantitatively and qualitatively) will still answer the research question without bias. The variables we chose to observe are not overly specific towards the specific type of tree at hand. |
| Experimental Design | [Our overall plan]: To observe the effects of tree location on its observable health. | [What independent variable will we test?]: Independent Variable: Location of the tree in a backyard (Central Location and Perimeter Location) | [What dependent variables will we measure and observe?:[ Overall Dependent Variable: the observable health of the tree; Quantitative Measurements :Approximate level of sunlight each try receives due to its respective location; Number of leaves that fall (daily) - relative to that type of tree; Sizes of the leaves in respect to that species of tree % of discolored leaves (sunny side and shady size); Number of cankers. Qualitative Observations: overall strength and health as perceived by looking or touching (Noting down any clear abnormalities) | [What variables will we keep constant?]: Duration: experiment will last for about two weeks; Time of recording observations; Weather: Both trees, although living in two separate houses, live in the same overall geographical region.; Humidity: Both trees, although living in two separate houses, live in the same overall region.; Amount of water given to each tree | [How will we record our data?] Daily Measurements: We will go outside to collect all quantitative measurements ; Daily Observations: We will go outside to make qualitative observations on the tree’s appearance, strength/stability, and coloration. | [Control group incorporation?] Because our experiment revolves around observing the trees’ health over a short period of time, we do not necessarily need a control group. We are not manipulating any variable ourselves, like in an experiment. | [Replication & Number of Trials] 2 Trees, Data will be collected each day, 2 weeks*7days=14 days of data | [Materials List] Notebook to collect data and observations, Ruler/measuring tape, Pen/pencil, Computer to graph/interpret the quantitative data, Trees at different locations |
| 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 |