College of Agriculture and Life Sciences

Proctor Maple Research

Current Maple Research Projects

Long-term Maple Health Study (2013– )

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a forest of tapped young maple trees in snow with tubing running from each tree

Our Long-Term Study, established in 2013, is one of our cornerstone research projects, designed to investigate how modern sap collection practices affect the long-term health of sugar maple trees and to discern any trends in physiological function caused by environmental changes. We measure trees' annual radial growth, sap volume, and sugar content during the sugaring season, as well as analyze their sap and wood chemistry. With four treatment groups – gravity-extraction, vacuum extraction, tapped without extraction, and untapped – we can distinguish between impacts on tree function from tap wounds and impacts from the amount of sap, and thus sugar, removed from the trees. This long-term dataset is critical for understanding cumulative effects that may not be apparent in shorter experiments and can serve as a baseline for studies of environmental change.

This study was initiated by Abby van den Berg, Timothy Perkins, and Mark Isselhardt and is supported by the US Department of Agriculture and the Vermont Agency of Agriculture. For more information, please contact Tim Rademacher or Mark Isselhardt.

Cornell Maple Climate Network (2025– )

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A blue cylindrical machine for monitoring sap flow strapped to a tree trunk

Proctor Maple Research Center is one of seven sites in Cornell's Maple Climate Network, which is testing advanced monitoring instruments to track sap flow and environmental conditions in real time. At each site, instruments collect continuous data from a single maple tree on sap flow under high vacuum, internal tree pressure, and other environmental variables such as air and soil temperature. The data, which provides an unprecedented view into the physical processes that govern sap movement, is publicly available through Cornell’s Maple Climate Network dashboard. The goal is to understand how weather and tree physiology interact to drive sap runs in modern high‑vacuum maple production systems, thus improving our ability to interpret and eventually predict sap flow patterns. This will help maple producers better plan operations and adapt to increasingly variable weather conditions.

This project is in collaboration with Adam Wild at Cornell University’s Uihlein Maple Research Forest in Lake Placid, New York.

Genetic Basis of Physiological Traits for Sugaring (2026– )

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a spray of scarlet maples leaves on an otherwise green leafy branch

Understanding why individual sugar maple trees differ noticeably in sap sweetness, sap volume, and growth, and how those differences are tied to the interaction between genes and environment, has long been a central question in maple research. In the 1950s, scientists began a landmark progeny study to explore the genetic basis of sap sugar concentration, germinating seeds from mother trees selected for their wide variability in sap sweetness. These saplings were planted in 1960 in common gardens at Proctor and Williams College's Hopkins Memorial Forest in Massachusetts to allow long-term comparisons among genetic lineages in different climates.

In 2025, we began relocating the 150+ surviving trees at Proctor and taking repeat measurements of sugar sap content. This new iteration of the study provides a rare opportunity to compare the evolution of sap sugar content over nearly seven decades using modern measurement techniques. In collaboration with our partners at Williams College, we have identified five other sugar maple progeny trials across the U.S and plan to incorporate them into our research.

This project has received support from the UVM Food Systems Research Institute. For more information, please contact Teaghan McAllister and Tim Rademacher

How Much Defoamer Is Too Much? (2025–2026)

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two men standing by a steaming, industrial evaporator, making maple syrup

Led by the Centre ACER in Quebec, this project brings together a coalition of maple research facilities, including Proctor, Cornell University, the University of Maine, and the Centre ACER, to refine recommendations for the use of defoamers in maple syrup production. Defoamers, or antifoaming agents, are commonly added during the boiling process to prevent excessive foam, which can cause sap to boil over and scorch syrup, leaving an off-flavor. Too much defoamer can leave behind residue in the syrup. Knowledge of precise ideal defoamer amounts, which might vary depending on evaporator size and production method, is thus essential for producers and regulators alike. Through standardized protocols and laboratory analysis of syrup from both research sites and the marketplace, the project aims to develop science‑based best practices for both conventional and organic defoamers – helping producers large and small achieve safe, high‑quality syrup while minimizing unnecessary residues and maintaining efficient, well‑controlled boiling operations.

This work is currently supported by the North American Maple Syrup Council. For more information, please contact Tim Rademacher and Mark Isselhardt

Antimicrobial Droplines and Spouts (2024–2026)

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plastic tap in a maple tree with bright green tubing snaking out

Sap yield per tap typically declines over time as microbes build up in extraction tubes. Decades of research have documented this yield loss and explored sanitation strategies to reduce it. In recent years, silver nanoparticles have been applied to a plethora of plastic materials due to their antimicrobial properties. We are investigating whether they can improve sap yields when applied to spouts and droplines during or soon after installation. The experiment measures sap volume and sugar content of treated and untreated trees at the individual tree scale and the mainline scale. In 2026, a subset of antimicrobial and standard spouts and droplines installed in 2025 was left in place to assess performance for a second year, compared to a newly installed set, allowing us to evaluate effectiveness over time. Results from this work will help inform producer decisions about tubing materials, replacement schedules, and cost‑effective yield management strategies.

This study, initiated by Timothy Perkins, is no longer funded and will be terminated in 2026. For more information, please contact Tim Rademacher

Interested in conducting research on our property?

Other Hosted Projects

Forest Health Monitoring Program

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The Forest Health Monitoring Program (FHM) was established in 1991 as a joint effort between the Vermont Department of Forests, Parks and Recreation (FPR) and the Forest Ecosystem Monitoring Cooperative (FEMC) to monitor the condition of a range of tree species in Vermont. After successfully establishing and conducting annual assessments on FHM plots in Vermont for almost three decades, the FEMC has expanded to surrounding states to yield a more complete picture of forest health across the New England and New York region (196 total plots). One of these long-term forest monitoring plots is located at PMRC. Annually, the FHM program visits each plot to collect data on forest stand composition and structure, canopy condition and crown health, tree regeneration, and forest stressors and threats using a variety of field collection tools and protocols. 

Funding Source: U.S. Forest Service, with support from the University of Vermont and Vermont Department of Forests, Parks, and Recreation. 

Contact: UVM Forest Ecosystem Monitoring Cooperative, femc@uvm.edu

FEMC logo - circle in four quarters showing mountains, salamander, waves, tree

Forest Canopy Tower Meteorological Monitoring

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The Forest canopy tower is one of 3 meteorological stations FEMC manages on Mount Mansfield. Meteorological data is collected at 4 heights along the tower from the forest floor to the canopy. The following are collected at all four levels: wind speed and direction, leaf wetness, temperature and relative humidity, while measurements of solar radiation and irradiance are taken at the canopy level. 

Funding Source: U.S. Forest Service, with support from the University of Vermont and Vermont Department of Forests, Parks, and Recreation. 

Contact: UVM Forest Ecosystem Monitoring Cooperative, femc@uvm.edu

FEMC logo - circle in four quarters showing mountains, salamander, waves, tree

Summit-to-Shore Snow Monitoring Network

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UVM’s Water Resources Institute and Department of Civil and Environmental Engineering partnered to install athe Summit-to-Shore Snow Monitoring Network of 22 monitoring stations in a transect through central Vermont, from the shore of Lake Champlain, up and over Mount Mansfield, and ending in Danville. This includes a site at PMRC, which has hosted the station since 2022. The stations monitor snow depth and associated meteorological variables, such as temperature, humidity, radiation components, wind speed and direction, and in some cases precipitation. These data are recorded in order to capture the role of elevation, aspect, variable forest canopy, and short-term and longer-term changes in weather patterns on snowpack accumulation and melt. We hope to measure long records of snow at multiple locations that help understand the nature of changes occurring primarily in the winter. This can influence forest ecology, flood risk, and land/atmosphere feedbacks.

Funding Source: Cold Regions Research and Engineering Laboratory (CRREL) 

Contact: Arne Bomblies and Beverley Wemple 

a person in winter gear examining a weather monitoring station in the snowy woods

Vermont Mesonet

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Vermont Mesonet is a statewide network of weather stations built to fill important data gaps and help communities better prepare for extreme weather and support agricultural monitoring and research. By using existing infrastructure and adding new stations in key high-elevation areas, like the western slopes of Mt. Mansfield at the Proctor Maple Research Center, the project gathers real-time weather information from across the state. 

That data makes a difference. It helps forecasters improve predictions, supports emergency responders during floods and severe storms, and gives farmers and researchers valuable insight into temperature, wind, snowmelt, and rainfall. These measurements not only protect public safety but also help maple producers understand conditions that influence sap flow and yields. 

A secondary station is currently in place at Proctor Maple Research Center, and there are plans to develop a primary station on the property in the coming years. 

Funding Source: Leahy Institute for Rural Partnerships, Cold Regions Research and Engineering Laboratory (CRREL). Related regional integrations are funded by the Environmental Protection Agency (EPA) to integrate the monitoring infrastructure into a regional mountain observatory network. 

Contact: UVM Water Resources Institute, Joshua Beneš

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National Atmospheric Deposition Program

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The National Atmospheric Deposition Program (NADP) is a cooperative research program that has monitored atmospheric data across North America since 1978. Operated by the Wisconsin State Laboratory of Hygiene at the University of Wisconsin-Madison, NADP maintains over 250 collection sites to provide long-term environmental data on the effects of air pollution on ecosystems and human health. The program is comprised of several networks that examine trends in concentrations of sulfur, nitrogen, mercury, ammonia, and per- and polyfluoroalkyl substances (PFAS, starting in Spring 2026) and how these pollutants are removed from the atmosphere through precipitation (wet deposition) and settling to the surface (dry deposition). The program brings together federal, state, tribal, and local governmental agencies, educational institutions, private companies, and non-governmental organizations to advance our understanding of how atmospheric processes impact air quality, water resources, and ecosystem health. This collaborative effort generates critical information for environmental management and policy decisions. The University of Vermont's Forest Ecosystem Monitoring Cooperative sponsors the Underhill site (VT99) in Vermont, which contributes to both NADP's Mercury Deposition Network (MDN) and National Trends Network (NTN) monitoring efforts. 

Funding Source: U.S. Geological Survey, Vermont Department of Environmental Conservation

General Contact: NADP Coordinator and Principal Investigator, Sarah Benish – sebenish@wisc.edu 

Local Contact: UVM Forest Ecosystem Monitoring Cooperative, femc@uvm.edu

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USDA UV-B Monitoring and Research Program

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The USDA UV-B Monitoring and Research Program (UVMRP) is the only US network providing nationwide surface monitoring of ultraviolet-B (UV-B) irradiance, an atmospheric radiation band of significant concern to USDA due to its known negative impacts on forests, rangelands, and crops. The appearance of an “ozone hole” over the Arctic in March 1990 spurred and sustains (reappearing in March 1997, March 2005, March 2011, March 2020) the USDA interest in documenting the baseline, variability and trending of UV-B across the Nation. Of note is that the National Weather Service’s nationwide network does not monitor UV-B irradiance. UVMRP's mission is "measuring ultraviolet radiation and studying its effects on agriculture, human health, and climate."

Funding Source: USDA – NIFA for Colorado State University

General Contact: Dr. Wei Gao – wei.gao@colostate.edu

Instrumentation Network Contact: George Janson – george.janson@colostate.edu

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PhenoCam

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The PhenoCam Network uses repeat digital photograph to track the rhythmic seasonality of vegetation activity in ecosystems across North America and around the world. This study of this seasonality is the science of phenology, and a phenocam is a digital camera specifically used to study phenology. From Alaska to Arizona, and from Hawaii to Maine, phenocams upload images to our server at NAU every 30 minutes, from sunrise to sunset, 365 days a year. Images and data products characterizing vegetation “greenness” are made publicly available in near-real time through the PhenoCam web page. The PhenoCam archive includes over 80 million images from almost 1000 different cameras. With a total of more than 6000 site-years of derived phenological data, and 75 cameras that have been in continuous operation for over a decade, the PhenoCam Network archive is the largest repository of phenologically-relevant repeat digital photography in the world. In addition to scientific research (over 400 papers have been published using PhenoCam Network data and imagery), PhenoCam provides unique opportunities for education and outreach. Engage in virtual travel through time and space by browsing the PhenoCam image archive

Contact: Andrew D. Richardson – andrew.richardson@nau.edu

series of four photos of same landscape in each season, a forest edge with a field in foreground

Air Quality Monitoring

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The Vermont Department of Environmental Conservation's Air Quality and Climate Division (AQCD) operates a permanent air monitoring site at PMRC. This site is part of the National Air Toxics Trends Stations (NATTS) Network which consists of 27 sites across the country, aimed at collecting long term Hazardous Air Pollutant (HAP) data. It is one of the few rural sites participating in the program. It is also part of the national Interagency Monitoring of Protected Visual Environments (IMPROVE) Program, aimed at measuring and preserving visibility in federal Class I areas. 

Funding Sources: Federal NATTS and PM2.5 grants

Contact: David Ruby – david.ruby@vermont.gov