6/24/22: Project waterlog underway

It was a hot one this week, but that didn’t slow us down. The current heat wave, paired with an absence of rain, will surely show some interesting fluctuations in our forestry plot data. How will this extended weather event impact root growth, sap flow, tree growth, and more? Only time, and future updates of this blog, will tell! In the meantime, take a look at what we got up to in the root lab:

Began tracing and observing root growth in our waterlogging trial trees

Monday and Tuesday were dedicated solely to our dear maples and magnolias. We have 24 maples: 12 sugar maples (Acer saccharum) and 12 silver maples (Acer saccharinum). We also have 24 magnolias: 12 star magnolias (Magnolia stellata) and 12 saucer magnolias (Magnolia soulangeana). We traced all 48 trees with paint pens on the rhizo-pot plastic windows. To the right you can see Isabella, our cello playing undergraduate student visiting from Iowa’s Grinnell College, tracing one of the maples. Look for updates on Isabella’s soil respiration project in the coming weeks!

Let’s get back to our roots. Based on how much growth we saw in the pots this week, we are planning on starting our waterlogging trial for all maple species next Monday (6/27/22). We will fully submerge 12 maples for a 2-week period (the other 12 maples are the control trees and they will grow in normal conditions). If there is not sufficient root growth by Monday, then we will delay the dunking of the trees for another week. Stand-by for updates on the magnolias, as their roots seem to be growing a little slower.

We used a green paint pen for our first tracing. Remember this! In coming weeks you will see new colors for each tracing session. Green roots will be the oldest age class. They are very wise and enjoy the occasional early bird special.

Dr. Luke McCormack taking on a posture eerily similar to that of Dr. Gachet in Vincent van Gogh’s 1890 portrait. Props to Isabella for this discovery of art imitating life! Image source

Experimented with graphing our waterlogging data using R software

For those of you who haven’t heard of “R”, it is a programming language scientists use to work with their data. I’m currently learning how to code, so bare with me as I trudge through this beginner’s stage!

This week I've been playing with old data from the 2019 waterlogging experiment. Here you can see photosynthesis rates on three different dates (before, during, and after waterlogging). I’m going to plot similar graphs with our NEW data in the upcoming months, so it’s important to figure out the best way to visualize the patterns we expect to see.

Many online resources are available for R and other programming languages. They can help you at every point of your data analysis. An online book that I have found extremely helpful is R for Data Science. It breaks up data science into six main stages: importing, tidying, transforming, visualizing, modeling, and communicating your data. This week I focused on the visualization component by playing around with different graphing options for how we can look at the comparisons between the waterlogged trees and their non-treated counterparts.

Weighed and tinned root samples for gymnosperm Root Lab project

Beginning in 2019, the Root Lab started a project focusing on gymnosperm root traits. You know those trees that keep their needles and leaves all year round? Those are gymnosperms (some gymnosperms also lose their foliage seasonally, but that’s a topic we’ll save for another blog post)! Jessica Langguth has been leading this project and is now putting the finishing touches on the analysis of the data we collected and what we can learn from those results.

Above are the root samples that I weighed and tinned. Samples have to be ground down to a fine powder before they can go the machine that analyses carbon and nitrogen content in the root.

These are the tiny metal tablets you are left with after tinning. “Tinning” is the process of placing a small amount of a sample, in this case 3-5 mg, into a tiny tin boat, and folding it up like a burrito. It is an oddly satisfying task!

Installed a dendrometer on a Bald Cypress “knee”

As mentioned in a previous post, a dendrometer is a tool we use to measure tree growth. Bald Cypress is a super cool species of tree that develops above ground roots called pneumatophores (also known as aerial roots … or knees, for those of you who prefer human anatomy references). These help the tree “breath” and are common in species found in swampy/wet locations. For the fun of it, we installed a dendrometer on a particularly pretty knee. It will be interesting to find out if the growth pattern matches that of the rest of the root system. Is it growing during the same time as the underground roots? Stay tuned to find out!

Marvin, long time employee and keeper of all the arboretum’s secrets (he won’t tell you where the morel mushrooms are, that’s classified root lab information) is seen here celebrating his dendrometer installation skills.