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Linking phenology to ecosystem processes in forests of the northeast


Monday, July 19, 2010, by Andrea Garcia, Adam Young, and Cory Teshera-Sterne
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We are working with Dr. Andrew Richardson and two of his postdocs, Koen Hufkins and Oliver Sonnentag, to investigate ways of monitoring and measuring the phenology (recurring life cycle events, such as flowering, spring green-up or senescence) of North American forests using webcams and digital imaging. This project is highly analytical and employs the use of computer programming languages such as R and MatLab. These programs let us process thousands of images so we can isolate ideal conditions in which to measure the vegetation indices for a given day or season. There are a multitude of variables that can confound our results such as individual camera settings, weather conditions, and positioning of camera. This work is part of a larger effort involving a national phenological observation webcam network, Phenocam, which includes webcams at National Parks, research sites, and other locations around the country.

Adam and Andrea are involved with writing computer code (mainly in R) that generates graphical output, downloading images from different sites all over the country, filtering these images and classifying them by weather conditions (clear, overcast, snow, etc.). So far a dozen sites have been analyzed in some way or another for a variety of vegetation indices and time series plots have been generated. Adam and Andrea, having little programming experience coming into the program, have “enjoyed” a steep learning curve when it comes to computer programming. So it is fair to say that they have learned quite a bit.

Cory, probably the most tech-savvy of the group, spent most of the beginning of the summer configuring cameras, some of which are essentially small, programmable computers. Currently, Cory is working on expanding the Phenocam website, which shows only current images, to display relevant data including current time series of phenological activity both from images collected at the site and satellite data. This will allow researchers to more easily compare phenological data collected via various methods, one of the main goals of our research.

One of our more interesting projects this summer was the installation of 14 webcams at the top of the EMS tower. We set up these cameras as an experiment to compare and contrast how different cameras influence measure the phenological response that are ultimately extracted from the collected image files. The cameras range from sophisticated surveillance systems to game cameras used by hunters. We assisted our postdoc mentors, Koen and Oliver, with building a weather-proof box (“Mr. Mad Scientist Box”) to contain a power source and data logger and with installing the cameras on top of the tower. This required carrying a 10’ board up the narrow tower, along with all the cameras and tools. It ended up being three long days of work, but was a great chance to see how the cameras all over the country that we are using data from are set up and all the hard work that goes into this research.

On a day to day basis we are glued to our computers programming, downloading and isolating images, researching phenology, conducting image analysis, and taking regular tea/coffee/hot cocoa breaks. We do get out of the office occasionally to help researchers doing related field work or to check up on our newly set up row of cameras and "Mr. Mad Scientist Box." 

There is still more work to be done with images we have downloaded and all the information they encompass, but we are aware that we are working on a new and unique project in the field of ecology. This adds to our enthusiasm for working at Harvard Forest this summer.

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