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[Research on] Early Tapping & Taphole Longevity Strategies 

Dr. Abby van den Berg, Research Associate Professor with UVM’s Department of Plant Biology and Proctor Maple Research Center, shares the results of a multi-year experiment conducted by the University of Vermont Proctor Maple Research Center to determine the net yields and impacts of fall and early-winter tapping, with and without subsequent “freshening” of the tapholes by re-drilling them wider and/or deeper.

2014 -15 Maple Tubing Research

In 2014 and 2015 the focus of the tubing and taphole sanitation research changed dramatically. Tests conducted in 2013 showed that if the spout and drop line were adequately sanitized sap yield comparable to a new spout and drop could be obtained. With the assistance of a grant from the Northeast Sustainable Agriculture Research and Extension program of the USDA and in cooperation with the Proctor Maple Research Center in Vermont, a variety of spout and drop cleaning and replacement options were tested to determine the extent of sap yield changes.

A History of Taps and Tree Size

The current ‘traditional’ tap hole number guidelines involve adding a tap for each 5 inch dbh above 10 inches dbh. ‘Conservative’ guidelines involve placing one tap in trees 12 inch dbh and a second tap in trees more than 18 inches dbh. The reasons behind the traditional guidelines are not stated in the North American Maple Syrup Producers Manual, but the conservative guidelines are suggested when there is concern for tree health. The purpose of this article is discover where these guidelines came from and to re-establish the reasons why they exist.

A Mathematical Model for Maple Sap Exudation

Sap exudation refers to the process whereby sugar maple trees (Acer saccharum) are capable of generating significant stem pressure in a leafless state, something that occurs to a lesser extent in only a few other related species such as birch and walnut. This exudation pressure is what causes maple sap to flow from a taphole in sufficient quantities to be harvested and processed into syrup. Exudation has been studied for well over 100 years and has been the subject of many scientific studies, but there is as yet no definitive explanation for how such large pressures can be generated in the absence of transpiration (i.e., when no photosynthesis occurs to drive the flow of sap).

A model of the tapping zone

This article is intended to accompany the Tapping Zone Model available to download at the University of Vermont Proctor Maple Research Center (UVM-PMRC) website. It provides a general explanation of the model and how it can be used. The model can be used to estimate the chances of hitting conductive and nonconductive wood when tapping, and this can be used to assess the sustainability of current or planned tapping practices.

A Model of the Tapping Zone

A model that calculates the proportions of conductive and nonconductive wood in the tapping zone of a tree over time given user-input values for tree diameter and tapping practices.

A New Take on Sap Collection

A new method of gathering sap from sugar maple saplings is being tested.