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Impacts of Climate Change on the Rhythm of the spring in Northeast Deciduous Forests

Sunday, August 10, 2014, by Ivonne Trujillo
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[Using Bucky to collect my leaf samples from the canopy]

This summer I had the opportunity to be an REU student for the Richardson Lab. It seems as if it’s the first week, and not the last week of the program. I’ve learned so much in this short period of time, and I will bring what I learned back to my university in Texas. This summer, I focused on the impacts of climate change on the rhythm of the spring in Northeast deciduous forests. I aimed to address some of the gaps that existed on the feedbacks between climate change and the seasonal cycles. I focused on leaf development for the red maple, red oak, and paper birch. Now, to characterize leaf development, I needed to find a way to collect my leaf samples at the canopy scale. It was really exciting to learn how to use the bucket lift, best known as “Bucky”, to collect my leaf samples from the upper canopy. Once I collected my leaf samples, I would return to the lab and used a set of instruments to measure leaf color, chlorophyll fluorescence, stomatal conductance, and the water content. However, I focused mainly on leaf color and used the data collected from the digital repeat photographs of the canopy and the scanned leafs from the scanner to compare vegetation greenness. The vegetation greenness was used to characterize the vegetation development across the forest. With my data, I can compare characteristics of different species at the leaf level and canopy scale.

Learning the significance of the Green Chromatic Coordinate (GCC), and how to calculate it made it really simple to understand my data and track the development of the canopy. Having to use R was a challenge for me, since I had no prior knowledge of it. However, my mentors guided me along the way and made it easier to understand. Using R, I was able to plot a set of graphs for each of my species where I compared the GCC values from the scanned leaves and the digital repeat photographs of the canopy. My prediction was that both of these GCC trends would be similar. My graphs proved that my prediction was correct, both trends were quite similar. The graphs also showed that tracking the vegetation greenness through time at a canopy scale with the tower mounted with cameras and at a leaf level with the scanner will allow us to accurately model phenology on both scales. 

[The digital scanner is used to scan the leaves, and provide color information similar to what the cameras on the tower are recording of the canopy][The tower that holds the cameras]














Now, if you're wondering what we will be doing about the additional data we collected of the other leaf characteristics, that will be used to understand the leaf physiology that leads to the Green Chromatic Coordinate (GCC) rate in each species.

This summer is a summer that will be unforgettable! I was able to use Bucky and be approximately 80 feet off the ground to collect all my leaf samples from the upper canopy. Then, I analyzed all the data for leaf color and compared the measurements at the canopy scale and at the leaf level. My prediction was correct, the GCC trends were similar, which is exciting because tracking the vegetation greenness through time at the leaf level and canopy scale will allow us to precisely model phenology at both scales. The results of this project will help us create a model that will better predict how ecosystems like, Harvard Forest respond to changes in climate.

Again, all this experience will be shared with my peers, family, and coworkers at my lab back in Texas. Words cannot explain how blessed I am for having the opportunity to do this project and for being able to share my summer project and experience with you. Also, for being well fed by our top chef, Tim, he did a great job this summer preparing delicious meals. I met a lot of great people this summer and this was indeed an amazing chapter of my life. 

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