Climate Change and Maple Syrup
4/7/09: Warm days and cool nights have started the sap running once again, and for Dr. Timothy Perkins, director of UVM's Proctor Maple Research Center, that means it's crunch time. “Ninety percent of our research is done in a 30 day time frame,” he explained. However, I was lucky enough to catch him on one of his rare indoors moments, where he was able to give me a short phone interview to tell me a little bit more about the PMRC and the research going on there.
Nestled in the woods of Underhill, Vermont, the Proctor Maple Research Center was officially established in the 1940s with the donation of a former family farm. However, the University of Vermont has been conducting research on the trees there for over 100 years. It is managed through UVM's department of Plant Biology in the College of Agriculture and Life Sciences. The PMRC's studies are funded by various state, local, and national entities including the USDA, the Vermont Department of Forest, Parks, and Recreation, and the Chittenden County Maple Sugar Maker's Association. The center is dedicated to studying and preserving the health of sugar maples, as well as providing public demonstrations of the sugaring process and educational outreach.
Research conducted at the PMRC has shown just how delicate a dance there is when it comes to variability in temperature and the sugar maple's sap production. It is known that the flow of sap requires thawing and freezing; to paraphrase a paper by researcher Timothy Wilmot, freezing temperatures lower the pressure inside a tree, causing the tree to take in water. Thawing temperatures raise that pressure, causing sap to flow out the taps. However, the whole of the tree is almost never at the same temperature. The trunk thaws more slowly than smaller branches, while the root system relies on ground cover like leaf litter and snow pack to insulate the soil and avoid freezing. Without that insulation, the soil temperatures can dip below freezing, which has been linked with a much lower (50% or less!) sap flow. In this way, less snow during the winter could harm Vermont's maple industry, with or without big temperature changes.
Perkins and Wilmot have already documented some change in the sugaring season. In a study funded in part by the USDA Hatch program and the North American Maple Syrup Council, the PMRC has surveyed various maple sugar producers to look for changes in the sugaring season. As Perkins told me, “Our findings are that the maple season throughout New York and Vermont has shifted a week earlier than it was 40 years ago. The end of season is one week earlier- there's a loss of about 10% of the season.” The PMRC (under the direction of Wilmot) is currently conducting research into how these earlier season starts have been affecting the sap run, with some interesting results. Based on research into the 2006 season, tapping done during above-freezing periods in January has produced more sap than tapping done later on in February or March. The regular March tapping season may be in for quite a change. However, Perkins noted that there hasn't been much of an effect on production yet, which may be due to a shift to more efficient collection methods like vacuum tubing.
As far as individual opinion about climate change, Dr. Perkins seemed convinced: “my person opinion is that climate change is real, and it's going to be affecting us for quite some time.” The studies he's conducted definitely seem to indicate a change. The gradual nature of the changes may make it difficult to observe from a personal standpoint. “[...]I don't think people tend to notice things like that that happen over a thirty or forty year time span. You don't really have a sense of how things change year to year, especially given the variability, but just in terms of experience, I think that we have seen that there have been seasons that tend to run earlier than what historically has been the norm here.” No matter how things may change, though, Dr. Perkins and the researchers at the PMRC will be ready and waiting to document it.
To find out more about the Proctor Maple Research Center, visit http://www.uvm.edu/~pmrc, or reach them by phone at (802) 899-9926. Interested individuals are welcome to call and schedule a tour of the facility.
