Harvesting Sap and Producing Syrup From Trees Other Than Maples, Birches, and Walnuts

Project Overview

Project Type: Graduate Student
Funds awarded in 2018: $14,848.00
Projected End Date: 11/30/2021
Grant Recipient: University of New Hampshire
Region: Northeast
State: New Hampshire
Graduate Student:
Faculty Advisor:
Dr. Heidi Asbjornsen
University of New Hampshire


  • Additional Plants: native plants, trees
  • Miscellaneous: syrup


  • Crop Production: agroforestry, forest farming, forestry
  • Education and Training: demonstration, extension, farmer to farmer, networking, on-farm/ranch research, technical assistance, workshop
  • Sustainable Communities: new business opportunities

    Proposal abstract:

    Syrup production is an important industry in the northeastern United States. Concern for the future of the sugar maple, a desire to extend sugaring season, and an interest in developing new products with unique tastes and market potential has spurred interest in syrup production from trees other than maple trees. Birch syrup is an economically important industry in Alaska and Canada and walnut syrup is of minor economic importance. Production methods for maple, birch, and walnut syrups are well-established. Given that maple syruping infrastructure and expertise is widespread in the northeastern United States, this region is ideal for the development of novel types of syrup. This 2-stage project will determine if syrup production is possible from 6 novel tree species common to the region first by determining if and when dormant-season sap flows occur in novel species and second by determining best management practices for harvesting sap and processing it into syrup. Results will be disseminated to syrup producers via producer meetings, production manuals, and free online instructional video segments.

    Project objectives from proposal:

    Objective 1. Identify the timing and environmental drivers of dormant-season sap flow in novel trees and the physiological mechanisms behind them. Knowledge of the timing of, and the environmental conditions that cause, dormant-season sap flow in novel species will help producers determine when and how long taps should be set out. A better understanding of the physiological mechanisms that drive dormant-season sap flow in novel species will help fill in scientific knowledge gaps and may further our understanding of dormant-season sap flow in maples, birches, and walnuts, the mechanisms for which are somewhat, but not completely, understood.

    Objective 2. Determine optimal tapping depths of novel species. Though 4-cm commercially-available taps work well with maples, birches, and walnuts, preliminary work suggests that dormant-season sap flow depths vary among species. Shagbark hickory dormant-season sap flows at depths between 1 and 2 cm, with barely any flow deeper than 2.5 cm (Moore, unpublished data). Four-cm maple taps are not ideal for harvesting hickory sap because they are seated tightly in shallower sapwood depths and can block sap flow.

    Objective 3. Determine the amount of nonconductive wood formed due to trees’ wounding responses to tapping, and whether mean annual diameter growth compensates for the loss of hydraulic conductivity. It is known that tapping sugar maples and paper birches causes the formation of a significant amount of nonconductive wood above and below tap holes, but that healthy sugar maples put on more than enough new girth growth each year to compensate for the loss of conductive wood if tapping guidelines are followed (van den Berg et al., 2012; van den Berg et al., 2017). This project would be the first to collect data towards developing such guidelines for other species. Species can differ widely in how they isolate wounds (Biggs, 1985; Dujesiefken et al., 2005). It is unknown how much nonconductive wood is formed in novel species because of tapping, and whether their annual stem growths compensate for this loss in hydraulic conductivity.

    Objective 4. Determine the palatability of novel syrups. The marketability of novel syrup is directly related to how good it tastes.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.