Author: Popp, Amy

STEM Seasonal Change Project

Hyo Shin , Olivia Smith, Mary Pate

Research question: What is the impact of amount of sunlight on leaf fall rate and percentage of green leaves?

Group members Mary Pate and Olivia Smith count fallen leaves and record data.

Model Analysis
This program is used to model the data because it is easier to see the relationships between the different variables. There are two dependent variables , the percentage of green leaves and leaf fall rate, and one independent variable, the amount of sunlight. As the bar of length of sunlight variable moves, the values of each independent variables change according to the equations that we got from fathom. This is a good predictor of the model except it might produce unreasonable values during summer or winter.

Graphs 1
This graph means how the leaf fall rate changes depending on the amount of sunlight.
Least Square Regression Equation:
%percentage of green leaves = 0.994(amount of sunlight) - 608
X-axis: amount of sunlight
Y-axis: leaf fall rate
Negative slope = amount of sunlight increases, the leaf fall rate decreases
Graph 2
Graph shows the relationship between minutes of sunlight per day and percent of leaves that are green.
Graph had a positive slope, which means as the minutes of sunlight goes up, the percent of green leaved goes up as well.
Considering the time of year and the location and the season, we expected the amount of leaves to go down.
There should be less sunlight which means less leaves on the trees because the leaves on the trees need energy, which they get from the sunlight.
Other actors contributes to the outcome of this experiment

Methods
When conducting the long term experiment, we kept a constant method. To collect the leaves, we used a plastic barrier to fence off a small area, about a foot or two wide. When we first went out, we took an initial count of all of the leaves on each of the branches of each of the trees. We also how counted how many of those leaves were green. When we went out after then, we counted how many of those leaves were still green as time went on and as the experiment progressed. During this experiment, we also considered many factors because they could change the outcome of the results. We considered how the amount of sunlight varied from day to day. These are just some if the factor that we considered when doing this experiment.

Group member Mary counts remaining green leaves on tree 2.

Conclusion:
Our group concluded that minutes of sunlight is the independent variable, while rate of leaf fall and the percent of leaf that is green are the dependent variables. This makes sense because sunlight is what causes photosynthesis. While our data was very accurate for this season, it may not be accurate for future seasons. This is true because as the seasons change many other conditions change as well. Our data is reproducible, because anyone can collect the data needed to duplicate this experiment.
Future work:
How did your experiment set-up and/or experimental results differ from the other class?
Locations
How could your experiment be modified to collect more reliable/reasonable data?
more distinct leaf catcher
more remote area

Group members Mary and Olivia count leaves that have fallen and collect data.