Environmental Effects on the Diameter of Trees By Ethan, Stuart, and Elliot

Introduction (3/19/18 - 3/20/18) This week, we are in Hubbard Gulch, located in Ben Lomond, California. Our experiment consisted of us roaming the redwood forest and collecting data around multiple different trees. This is important because it shows what we need to put into the soil if we want to replant healthy trees. Alongside this, it is beneficial for us to know how to judge whether a forest is healthy or not. We will be testing for how soil pH, water nitrate levels, water phosphate levels, and distance from water source affects tree diameter.

Environmental Effects on the Diameter on Trees Research Question: How does the environment affect the health of trees? How do elements in the water supply affect the overall diameter of trees? Claim: Original Claims: The more nutrients available to the tree, the larger the tree is. The more basic the soil is around the tree, the larger it will be. If the tree is closer to the water supply, the larger it will be.

Materials and Methods Materials: Rapitest Digital Soil pH meter Soil corer Plastic Bags Water Bottles API Pond Master Test Kit Tape Measurer Methods: Field: Measured the circumference of tree Measured distance from base of tree to nearest water supply Collected small sample of dirt 1 meter away from base of tree. Collected water sample for nearest water supply. Lab: Tested for nutrients in water Tested for pH levels in dirt samples.

Evidence Correlation: More nitrates = larger tree T-Test p Value: 0.0013 There is a 99.87% chance that the difference between the experimented means are real. There is almost a correlation between the pH level and the tree diameter: The higher the pH (more basic), the larger the diameter.

Evidence (continued) - soil color No correlation No correlation

Reasoning Future Research Right about… pH Nitrate Why not others? There are a lot of factors that contribute to tree size--age, sunlight, and many other things we did not have time or resources to measure. A reason for why the pH was so low for some soil samples is because when leaves fall off of redwood trees, they provide acid for the soil when they break down. Future Research We would study pH and nitrate levels in completely different locations because we saw a correlation with these two things.