Photographing Plant Phenology

By: Liz Ivkovich, Sustainability Office

On Tuesday Nov. 15, Dr. Andrew Richardson will present “Climate change, phenology, and ecosystem processes: what we are learning from the PhenoCam network” as part of the GCSC Seminar Series. The presentation will be in 210 ASB at 4:00 pm.

The latest image from a forest floor camera in Intervale, New Hampshire. Via the PhenoCam Network.

The latest image from a forest floor camera in Intervale, New Hampshire. Via the PhenoCam Network.

Across the University of Utah campus, the last remnants of our green foliage are now little brown piles scattered on the sidewalks. If the leaves seem to be falling later than they did when you were a kid, that’s because they are. Across North America, the growing season is getting longer each decade. Our long-lasting leaves are an indicator of this continental-wide trend, the kind of indicator that Harvard physiological ecologist Dr. Andrew Richardson uses to understand the ecological impacts of a warming climate. Richardson will discuss how he studies leaves and why they matter during his seminar for the Global Change and Sustainability Center on Tuesday, Nov. 15, 4:00 pm at 210 ASB.

Richardson installing a camera at the SPRUCE experiment in northern Minnesota. Courtesy of Andrew Richardson.

Richardson installing a camera at the SPRUCE experiment in northern Minnesota. Courtesy of Andrew Richardson.

“Since the 1970’s, the growing season has been extending by about two to five days per decade because of warmer temperatures,” Richardson explained. “It is expected that these shifts will continue as the climate continues to warm.”

Richardson researches changes in the growing season through his PhenoCam Network, a linkage of 350 web cameras across North America. The cameras are positioned close to foliage. Every 30 minutes, the entire network snaps a photo. These photos are collected and analyzed by a computer program that quantifies the color shifts in the foliage. This data is then synthesized into large scale climate models to help Richardson understand how North American phenology – the seasonal cycles of plants – is impacted by a warming climate.

Richardson originally set up a single camera in New Hampshire’s White Mountains to grab cool snapshots of changing leaves for his research posters and powerpoints. One of his PhD students discovered that by analyzing the color of the leaves, they could use the photos as quantitative data. This data is evidence of the exact time the leaves flower and bud each season. Budding, flowering, changing colors, and other phenological events are highly sensitive to year-to-year variation in weather. These changes in leaf colors tell Richardson when a plant is engaging in photosynthesis.

Camera on the Niwot Ridge tower at the Mountain Research Station in Colorado. Courtesy of Andrew Richardson.

Camera on the Niwot Ridge tower at the Mountain Research Station in Colorado. Courtesy of Andrew Richardson.

“We are particularly interested in leaf phenology because leaves are where photosynthesis occurs,“ Richardson explained. “Without photosynthesis, we don’t have plant growth, and photosynthesis is important because it takes carbon dioxide out of the atmosphere. So when plants are photosynthesizing, they help offset fuel emissions that are contributing to climate change.”

Because phenological events are sensitive to variations in weather, they are also sensitive to longer-term changes in climate. A warming climate means a longer growing season. For grassland regions, this longer growing season will be offset by a summer drought.

“Our analysis shows that by the end of the current century, warmer temperatures will cause plants to start being active earlier in spring and remain active longer in fall. That will increase grassland productivity. Hot, dry conditions during the summer will reduce grassland productivity.” Richardson concluded, “Basically we are having a lengthening of the growing seasons offsetting a drought-driven decrease in productivity.”

Richardson and team hope to have as complete a sampling as possible of North American ecosystems, enabling them to develop climate models to help predict future changes in phenology. In order to do this, they could use the help of interested Utahn citizen scientists and researchers.

PhenoCam tower at Harvard Forest, MA, with cameras mounted at the top. Courtesy of Andrew Richardson.

PhenoCam tower at Harvard Forest, MA, with cameras mounted at the top. Courtesy of Andrew Richardson.

“There are no cameras in Utah,” Richardson commented. “We would be very interested, especially with your nice aspen forests, to have some cameras there.” Information about participating in the network is available on the PhenoCam website. You can also ask him in person at his presentation on Nov. 15, 4:00 pm, ASB 210.

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