Measuring the Impact of Increased CO₂ on Tree Growth

In this activity you will go in to the virtual forest and download data from a tree-growth monitor called a dendrometer. The data will then be used to plot graphs of tree growth against time. Data will be available for trees from both control and treatment rings to allow graphs to be compared for baseline CO₂ and high CO₂_. This exercise demonstrates the effect of CO₂ on tree growth and how the carbon and water cycles in plants.

How do tree trunks grow?

How does a Dendrometer measure tree trunk growth?

This short (5min) video explains how a dentrometer can measure the increase in circumference of the tree.

Step One: Downloading the data

Find the dendrometer and download the data (look for question mark symbol on the tree)

Step Two: Looking at trunk circumference over time

Investigating tree growth over time

Working from the downloaded spreadsheet, go to 'ring means' tab (the data spreadsheet contains multiple sheets of data, data is tabulated at 2 points each day over a week in June 2018, data is recorded as the change in trunk circumference (mm) compared to day 1)

a) Plot a graph of average relative circumference vs time over the week for the ambient (control) rings

b) Suggest a reason for the general increase in truck circumference over the whole week

c) The trunk circumference changes between night and day. Suggest an explanation for this observation.

d) Suggest an experiment to test the hypothesis you suggested above.

Step Three: The effect of eCO2 on trunk growth

The effect of elevated CO2 on tree growth

a) Add a plot average relative circumference vs time over the week for the raised CO₂ (treatment) rings

b) Suggest an explanation for the difference in change in circumference between trees in the ambient and elevated CO₂ atmospheres.

Paste in your favourite graph here

Measuring the Impact of Increased CO2 on Tree Growth

Measuring the Impact of Increased CO₂ on Tree Growth