By Sarah Fecht
A new rooftop camera at Columbia University’s Lamont-Doherty Earth Observatory will help researchers study how the local forest is responding to the weather, seasonal shifts, and the changing climate.
It also offers a gorgeous view of the colorful treetops surrounding the campus in Palisades, New York. Via the camera’s livestream, viewers can check out the fall foliage, watch the trees swaying in the wind, and see if they might spot a peregrine falcon swooping past.
Mukund Palat Rao, a recent graduate who works in Lamont’s Tree Ring Lab, got the idea for PhenoCam from fellow grad student Bar Oryan. Oryan studies earthquakes, but for fun he had taken hourly photos of the treescape from his office window and compiled them into a time-lapse video. He emailed the video, which shows the trees progressing through a year and a half of seasonal changes, to the Lamont community. “Mukund replied and said, ‘You know what, we can actually use these pictures for scientific purposes,’” Oryan explained.
Video: The new camera installation was inspired by graduate student Bar Oryan’s time-lapse video of the changing seasons on the Lamont campus. The video is composed of hourly snapshots from Oryan’s office window between November 2018 and May 2020.
“I knew that there is this entire network of cameras similar to what Bar had set up that record seasonal changes,” said Rao, “and that there are none on the Lamont campus or anywhere close to this area. I thought that it was a really nice opportunity to set this up.”
With some funding from the Chevron Student Initiative Fund, the two graduate students purchased a camera and installed it on the roof of Lamont’s Oceanography building. Perched on top of the building, PhenoCam takes photos of the surrounding forest from sunrise to sunset so that scientists can better understand the region’s phenology.
Phenology (which is where PhenoCam gets its name from) is the study of natural phenomena that vary with the seasons and other cycles. For example, one question that Rao and his colleagues are interested in exploring is, how is the timing of spring and autumn altering with climate change? With rising temperatures, scientists expect springtime leaf-budding to get earlier, whereas leaf-dropping in the fall may be delayed.
Changes in tree timing are important “because so many things within the ecosystem depend on trees,” said Rao. If the leaves come out before the forests’ insects have hatched, the insects will miss out on their preferred food. Similarly, if migrating birds miss out on the peak of springtime, they will have fewer insects to eat when they arrive at the forest. “And so this entire ecosystem would be out of balance if these things are not synced up,” Rao explained.
Gif: PhenoCam captures the shift to peak fall foliage between middle and late October.
The researchers are also looking forward to pairing the PhenoCam observations with data from a network of dendrometers that are measuring tree growth around the campus. The dendrometers measure how tree trunk diameters grow or shrink depending on daily rhythms and rainfall patterns. For example, the researchers have observed that, just like a houseplant, the tree trunks shrink slightly during dry spells, and rebound once it rains. Rao said PhenoCam may be able to help them explore this phenomenon higher up in the trees, at the level of the branches and leaves.
In the springtime, PhenoCam will also help them to study a phenomenon where some trees, such as oak trees, begin growing before they put out leaves. The campus dendrometers will help them to measure when exactly the trees start growing, while PhenoCam will capture when the leaves come out, so the researchers can measure how much time lapses between when the leaves come out and the trees start growing.
Understanding tree growth is important not only from an ecological perspective, but also because of its implications for climate change. As tree leaves convert carbon dioxide into sugars during photosynthesis, they are taking planet-warming emissions out of the air and storing them away. Rao is researching how the changing climate could affect how much carbon trees and other vegetation are able to pull out of the air.
“Forests and vegetation have taken up almost 30 percent of the carbon dioxide that we have put into the atmosphere. So in a way, they are buffering us from the worst impacts of climate change,” said Rao. “If, under climate change, the forests lose this ability to take up carbon and store it, because of fires or droughts, then that would actually exacerbate climate change as well, and have CO2 concentrations rise faster than they are.”
As part of a larger PhenoCam network, the cameras at Lamont will help to fill in a gap in wider geographic trends in phenology. With cameras set up around the world, the network can help scientists find out if the timing of spring is shifting faster in Montreal versus Tallahassee, or how the growing season is changing at the bottom of a mountain versus at its peak.
“With these cameras, we can now look at much larger spatial scales,” said Rao. “It’s nice that our camera is part of the network, because we have this other new data point that fills in an area where the network did not have a camera before.”
Content Manager, State of the Planet
Earth Institute, Columbia University