On Monday, I got to lead a field lab for the Semester in Environmental Science, and excellent immersive semester taught by PIs at the Ecosystems Center at MBL that teaches undergrads visiting from different colleges and universities fundamentals of ecosystem ecology and biogeochemistry. The first part of the semester focuses on field methods and lectures, and then the last six weeks of the course is a student-led independent project.
It was such a great experience to work with a large group of bright students in the field, and teach them the ways of the LiCor 6400! The lab consisted of a few elements - collecting PAR (light) data at multiple canopy heights, collecting leaves, and measuring rapid light response curves and ambient measures of photosynthesis and respiration. These protocols allowed the students to explore how light controls carbon exchange in sun and shade leaves, as well as light-enhanced dark respiration by logging Rdark continuously over a 10-minutes period after shutting the light source off.
Today and tomorrow, I'll work with the students to make sense of all these values, and create a light-driven model of canopy carbon exchange. It's been a great exprience so far, and I'm happy to get back into teaching as a post-doc!
This summer brought the opportunity for me to mentor and work closely with an undergraduate from University of Chicago through the Metcalf Scholars program at MBL. I had such a great experience working with Jonathan, and together we collected an enormous amount of data! Jonathan excelled at very quantitative elements of the work - including learning both MatLab and R programming to convert satellite data values into usable metrics describing fluorescence and gross primary productivity.
The summer's research culiminated with a poster session for all the Metcalf Scholars last Thursday.
After returning from ESA in Baltimore, I traveled with Jonathan again to Harvard Forest for our August measurements (only September left!). We again used "Bucky" the canopy lift to obtain leaf-level measurements of photosynthesis and fluorescence which will use to scale to the canopy, and regional levels.
Some photos of us 60 feet up waiting for the fluorescence values to stablize before taking a measurement. We looked at Fluorescence in leaves that were dark adapted, adapted to ambient light conditions and high-light adapted (PAR = 1500+). Using a response from these variables, we can construct a model of fluorescence under different light conditions in Oak, Maple, and Beech across the growing season.
In addition to our monthly monitoring of leaf fluxes, we were able to collaborate with Jim Kellner and his graduate studetn Carlos Silva, who are using hyperspectral high-resolution imaging to observe and analyze the same parcel of forest that we are monitoring with NDVI and RGB imaging, and solar-induced fluorescence. This multi-layered approach will allow us to correllate fluxes across scales and better quantify actual real-time GPP values of Harvard Forest.
The equipment that Carlos and Jim brought up to the top of the tower was incredibly impressive - they can obtain 1 cm2 resolution of all wavelengths of reflectance from leaves - and at that scale multiple measures from a single leaf! They repeated these scans every 15 minutes for the entire day to see how photoperiodic variation in PAR and temperature impacts these measures.