The Living Breathing Forest

2017 Middle School Girls Math and Science Day

Michigan State University

March 4, 2017


Introduction to Photosynthesis

In the next 30 minutes, we will visually explore how photosynthesis varies as a function of different environmental factors. We will model photosynthesis at the scale of individual leaves, working our way up to entire forests.


What is it?

pho·to·syn·the·sis

/ˌfōdōˈsinTHəsəs/

noun

the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct.


How does it work?


How do we measure it?

LI-6400 Portable Photosynthesis System

Modelling Photosynthesis


Activity 1: Leaf Level Photosynthesis

We will explore how photosynthesis at the leaf level changes with temperature, sunlight, and humidity using a native Michigan pine species.


Jack Pine (Pinus banksiana)
Distribution of Jack Pine Trees

Go here for the first activity. Reflect on the following questions:

  • How does photosynthetic rate change as temperature changes? Why do you think this pattern occurs?
  • How does photosynthetic rate change as sunlight changes? Why?
  • How does photosynthetic rate change as humidity changes? Why?

Activity 2: Forest Level Photosynthesis

We will explore how daily photosynthesis at the forest level changes with temperature, sunlight, and humidity using observations from a coniferous forest in Washington. Click on the images for a closer look.

Before we get started, let's discuss how photosynthesis is measured over an entire forest.



Go here for the activity. Reflect on the following questions:

  • Explain the daily photosynthesis pattern. Why does photosynthesis peak at the middle of the day?
  • Do cooler or warmer days lead to higher rates of photosynthesis? Why?
  • Do sunny or cloudy days lead to higher rates of photosynthesis? Are you surprised by this result?
  • Select conditions to maximize photosynthesis over the course of a day.
  • Select conditions to minimize photosynthesis over the course of a day.

Wrapping Up What We Learned


Summary:

  • Using modern technology, we can measure photosynthesis at a variety of scales and unique locations.
  • Temperature, sunlight, and humidity all affect photosynthesis.
  • The combined effects of these factors can lead to surprising results when observing forest-level photosynthesis.

Questions:

  • Did you learn anything new today?
  • Do you have any questions based on what we did today?

More to Explore

We have compiled a list of websites with more information for you to share with your family and friends.


  • "How Do Forests Breathe When Climate Changes?" Video on YouTube

  • Photosynthesis Lesson and Videos from Khan Academy

  • "How We Measure Photosynthesis" Video on YouTube

  • Webpage for Our Research Lab

Collaborations

This website corresponds to a presentation for the Graduate Women in Science Mid-Michigan Chapter's 2017 Middle School Girls Math and Science Day. We would like to thank the following organizations for making this presentation possible.