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Harvard Forest Symposium Abstract 2017

  • Title: (Re)expansion of the maple syrup industry in New England: projecting where the taps will be in a changing environment
  • Primary Author: Joshua Rapp (Harvard Forest)
  • Additional Authors: Matthew Duveneck (New England Conservatory); Jonathan Thompson (Harvard Forest)
  • Abstract:

    The cultural and economic importance sugar maple is nearly unrivaled in eastern North America. In addition to its wood providing high value lumber and its leaves providing the brilliant backdrop for the “leaf-peeping” autumn tourist economy, its sweet sap is the raw material for maple syrup, one of the few wild-harvested agricultural products in North America. While U.S. maple syrup production reached its peak around the Civil War before beginning a long decline, recent technological advances and rising demand has spurred new growth in the industry. New England leads the U.S. in maple syrup production, and is the region with the fastest growth. This work will provide resource managers, maple producers, and policy makers with useful information on trends of maple resource availability for a growing forest industry.

    To explore possible growth in the industry, we mapped the potential taps in New England using FIA data and the Landis II forest landscape model. Using conservative tapping guidelines based on tree diameter from the North American Maple Syrup Council, we calculated the number of taps per acre for both sugar maple (Acer saccharum) and red maple (Acer rubrum) in each of the FIA plots included in the imputed forest composition map of Duveneck et al. (2015) to create a map of potential taps across New England. We then used Landis II projections, which provide biomass and age estimates for individual species at future time steps, to project the number of taps across the landscape given likely scenarios of climate, land-use, and forest change. To translate biomass and species age to potential taps, we used FIA data to relate biomass and maximum species age to numbers of taps per plot. At the plot level, our estimates of tap density are strongly correlated with the number of taps calculated directly from tree diameters (r = 0.9), suggesting this approach gives realistic estimates when projected across the landscape.
    We compared county level data on number of taps from the National Agricultural Statistics Service 2012 census to our projections of potential taps aggregated to the county level across the region. On a log-log scale our predicted potential taps explained 51% of the variation in reported taps at the county level, with a 10% increase in potential taps leading to a 7.5% increase in reported taps. Vermont had the most potential taps, consistent with its position as the state that produces the most maple syrup, but Maine also had many potential taps. Under scenarios that did not include harvest or development (‘grow-only’), potential taps increased substantially by 2065, under both current climate and a projected warmer climate. Climate warming was predicted to increase the number of potential taps slightly. When current trends of land-use were included in the projections, the number of taps still increased, except in Maine where current timber harvesting practices are projected to cause a dramatic decrease in the number of potential taps under both the current climate regime and climate warming. This shows the importance of land-use in determining the future maple tapping resource.

  • Research Category: Conservation and Management
    Regional Studies