TREX Day 3 – Plant Life
By Rayna Higuchi ’20
Today was a pants kind of day. Our group started off adventuring into the woods behind the house to take something called a transect. Professor Dave Des Marais walked 50 feet straight through the plants with a tape measure to create a line for us to follow. Every ten feet we threw down a set of four flags in a circle with radius 1 meter and studied the plants within that space. We counted the percentage ground cover of a variety of plant types, as well as the number of Ohi’a trees within the circle. We then cut small branches off Ohi’a trees within our circles and ran them back to the house to study the tree’s water pressure, chlorophyll levels, and leaf thickness. This can give us a good idea of the plant’s health, thus providing insight into the overall health of the forest area.
Professor Des Marais and I take note of the percentage ground cover of each plant type. [Photo by Sierra Rosenzweig]
Caio Guilherme Pereira (TA) watches as I take measurements of a tree’s water pressure. [Photo by Sierra Rosenzweig]
Ohi’a is an important plant in Hawai’i, as it makes up a large portion of the forests. It is a highly diverse plant and is currently threatened by an invasive spore, causing Rapid Ohi’a Death. We will not be studying this phenomenon in detail, but we need to be careful in our study of the plant and traversal through the forest, as patterns would indicate the spores are spread mainly by human contact.
A healthy Ohi’a tree in the foreground, with the brown woody stem. [Photo by Sierra Rosenzweig]
Once our first transect was complete, we reeled the tape measure back in and took another transect in a different direction. As the team took these measurements, individuals would take a break to practice flying the drone. We flew it up to 400 feet, the maximum allowable height by regulation, and then brought it straight back down. It was exciting for me personally as I’ve never actually flown a drone before! So that was a first.
My first drone flight! Abby, one of the TAs, demonstrates to me how to work the drone controls.
We broke for lunch, and then regrouped to sort the data. Once we had input it into a data spreadsheet, some people graphed it. I and others went to visit the university of Hawai’i at Hilo to talk with a professor about Rapid Ohi’a Death, and to learn about his use of drones in surveying infected trees. To round off the visit, he showed us several videos of the lava flow from the eruption this past summer.
Then, we returned to our home, with a brief grocery stop to replenish our supplies. Fourteen students eat an astonishing amount. Following dinner, we met to discuss our findings and our plans for tomorrow. Hopefully, we’ll have the chance to see recently formed rock. It’s a once in a lifetime experience to stand on earth that didn’t exist a few months ago. Crazy thought: this land is younger than my baby cousin!