Plant Physiology (Biology 327) - Dr. Stephen G. Saupe; College of St. Benedict/ St. John's University; Biology Department; Collegeville, MN 56321; (320) 363 - 2782; (320) 363 - 3202, fax; ssaupe@csbsju.edu |
Tapping a Sugar Maple Tree
Background Information:
Under the appropriate conditions, sap will readily flow from a wound in the xylem of
sugar maple trees. To collect the sap, Native Americans simply chopped into the trunk
with an axe (Swain, 1981; Cleveland, 1987). This technique was ultimately replaced by the
less destructive method of boring a hole into the xylem and inserting a tube
called a spile to collect
the sap. In this lab, we will use a brace and bit to drill a hole. However, large sugar
operations use a portable electric drill or drill bit mounted on a chainsaw. Spiles can be made from hollowed sumac
stems (Swain, 1981) or from a variety of other materials such as copper tubing. A sack,
can or other container is hung on the spile to collect sap. Many commercial
operations attach plastic hoses to the spiles under a vacuum to help withdraw
sap. We will use the following procedure for tapping:
Protocol:
The hole should be
approximately waist high (1 meter). Avoid scars, burls and
previous tap holes (about 6 inch horizontally and 2 inches vertically). Drill one tap per tree, although larger trees can have more taps
(Swain, 1981; Holan, 1986). New guidelines suggest that trees smaller than
12 inches in diameter shouldn't be tapped and that a maximum of two taps be
placed in a tree. Traditionally, the number of taps was related to tree
diameter: 10-14 inches = 1 tap; 15 - 19 inches = 2 taps, 20 - 29 = 3 taps;
25+ = 4 taps. If the taps from previous seasons haven't sealed, the
tree should not be tapped.
Questions: Does the sap have a taste? If so, describe it. How much sap did you
collect? What was the rate of sap flow? How does sap flow relate to temperature? What
color is the sap? Is the sap contaminated with foreign materials? If so, what are they and
where did they come from? Squirrels like sugar maple sap; did you see any evidence of
squirrels feeding on maple sap? Do the taps attract any insects? Do different trees vary
in sap flow? Do trees vary in the duration of sap flow? Do trees vary in the temperatures
at which flow occurs? Does the sap contain cells? Does sap flow rate vary with
species?
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Last updated:
01/07/2009 � Copyright by SG
Saupe