Recipient Organization
UNIVERSITY OF VERMONT
(N/A)
BURLINGTON,VT 05405
Performing Department
Plant Biology
Non Technical Summary
Climate change has reduced the length of the maple production season by 10% over the past 50 years. The economic impacts of this significant reduction have only been mitigated by the advent of new equipment and tapping practices that have enabled producers to achieve substantial increases in the quantity of sap able to be extracted annually from individual trees. This project will use a novel experiment apparatus to examine the impact of a factor that could substantially affect the total quantity of sap able to be extracted from trees - the accumulation of nonconductive wood from previous tapping on sap movement within tree stems. This work will quantify the impacts of this factor on sap movement and sap yields, and facilitate the development of tapping practices to mitigate its impact and maximize the amount of sap extracted from trees. Ultimately this will help maple producers in Vermont implement practices that maintain positive economic outcomes, and the long-term sustainability of their operations.
Animal Health Component
90%
Research Effort Categories
Basic
10%
Applied
90%
Developmental
(N/A)
Goals / Objectives
The overall goal of the proposed project is to determine the impact of nonconductive wood (NCW) on sap movement in maple stems under vacuum. Two supporting objectives will be completed to accomplish this goal:Construct and test a device that will allow us to examine the rate and resistance to the flow of sap in excised maple stems, andQuantify the rate and resistance to sap movement through maple stems with varying levels of NCW.
Project Methods
To accomplish Objective 1, we will design and construct a device to test the rate of sap flow and resistance to sap movement in cut maple stems. Briefly, a small (4-6') chamber will be constructed in which a cut maple stem can be fully submerged and sealed. The chamber will be constructed so that deionized water can be used to flood the chamber, and vacuum can be placed on the chamber in order to de-gas the water prior to any study in order to prevent xylem embolisms. A port will be included in the chamber that will allow a dropline (tubing which connects the taphole to the vacuum collection system) to be connected to the stem. In general, the chamber design will enable a stem segment to be tapped and a spout and dropline installed prior to placing it in the chamber. Vacuum can then be applied to the dropline, and the rate of sap flow measured after steady state conditions are achieved by measuring the quantity of water extracted from the dropline during a defined time period at a given vacuum pressure. These data can also be used with stem dimensions to calculate the resistance to sap movement within the stem. To accomplish Objective 2, in the maple production season of Year 1, healthy, previously-untapped maple trees will be tapped with different diameters (5/32, 1/4, 5/16 and 7/16"), depths (½, 1, 1 ½, 2, and 2 ½"), and numbers (1-4) of tapholes in order to generate stems with varying levels of nonconductive wood (NCW). Five to ten trees will be left untapped and used as controls, and each treatment will be replicated on 3-5 trees. Trees will be left for at least one year to allow the NCW column associated with each taphole to fully develop. In project Years 2 and 3, these stems will be individually cut and the device will be used to measure sap flow rates and stem resistance in each stem. To accomplish this, generally, each tree will be felled with a chainsaw, and a 2' stem subsection containing the taphole(s) and NCW column(s) will be removed. Each stem subsection will then be weighed and its dimensions measured. It will then be tapped with a standard 5/16" spout, immersed in the de-gassed water in the test chamber, and connected via tubing to a vacuum pump and collection vessel. Vacuum will then be applied at standard maple industry levels (26" Hg), and the volume of water extracted will be measured for a period of time (2-4 hours). Afterwards, the segment will be cut into 2" cross-sections and the volume of NCW and CW within it will be measured using digital photography and image analysis. Together, these data will be used to calculate the rate and resistance to sap movement per volume of conductive and nonconductive wood. ANOVA will be used to determine if the rate differed significantly between the NCW treatment levels, and regression analyses will be used to determine if a significant relationship exists between NCW volume and the rate of sap movement. The results of these analyses will enable us to accomplish the overall project goal to determine the impact of NCW on sap movement through maple stems, and ultimately enable us to inform the development of tapping practices that optimize sap yields and long-term tree health.The results of this research will be communicated to maple producers and industry members in Vermont and throughout the maple-producing region of the U.S. in a variety of ways. They will be incorporated into a technical report that will be published in a maple industry publication, and posted online at the UVM-PMRC and other Maple Extension websites. We will also present the results and project information through seminars at maple industry conferences and meetings, and online. Maple producers will be able to use project information to implement practices that increase their annual sap yields and revenues, further reduce the impact of sap collection on the health of their crop trees, and ultimately help maintain productive and sustainable operations. The outcomes of this project will be evaluated by counting the number of producers reached with project information, and conducting follow-up surveys with these producers to assess their adoption of practices and impacts on sap yields and tree health.