Summary: Maple producers may wish to estimate the potential number of taps per acre to assess the productive capacity of an area, and to aid in estimating the costs for installing tubing systems or buckets. Once you know the number of taps per acre, you can compare sites and estimate costs using the tapping and tubing cost estimator available at www.CornellMaple.com  (look at publications” and then “tools”).   

Two methods allow producers to collect data that estimates the number of taps.  One method uses a tape measure to establish 1/20th acre plots as previously described.  The other method uses an angle gauge to estimate the number of taps per acre from a series of sample points.  Both methods are valid and useful, but use different mathematical principles.  

The data will be recorded and tabulated using the table at the end of this article.  Use three to five sample points for each area of the sugarbush that has very similar characteristics of trees size and stand density.  

Variable Radius Plot: An angle gauge is the tool used to determine which trees to measure when using this variable radius plot method.  Using this method makes measuring out the plot area unnecessary saving significant time.   

Using the angle gauge a maple producer can quickly identify the trees that are in or out of the plot. The angle gauge must be held a fixed distance from your eye for it to work properly and the surveyor’s eye is kept over plot center or “the point”  when using an angle gauge.

When using an angle gauge the user must count trees that are large enough to fill the width of the angle gauge window, as viewed from the “point”, the center of the plot. Randomly select a spot in the sugarbush.  At this spot, called the point, hold the angle gauge at arms length, at eye height, 25” or as prescribed by the manufacturer from your eye as demonstrated in the photographs.  

Many angle gauges have a string or chain that lets the user know the set distance. Keeping your feet on the same point rotate your whole body 360º or in a complete circle while you identify which trees fill the gauge window while in the 10 BAF direction.  Having a second person measure each tree as they are identified can make this project even easier.  

Ignore all trees that do not fill the window no matter how big they are. Each angle gauge is set at a certain basal area factor, or BAF, the table below is calculated to use with the 10 BAF window. Each tree that fills the gauge window is in the plot and needs to be measured and added to the tally.

 Use the angle gauge at each point to count all red or sugar maple trees that fill the 10 BAF window and record them as TPP or “taps per point”. In the table,  assign each tree to the appropriate DBH class by having a second person measure each in or window filling tree with a circumference tape or tree scale stick.  

Place a dot or dash in the box under the appropriate DBH category for each tree that filled the window when inspected at 4.5’ above ground.  For each point on the table, multiply the number of taps per point (TPP) in each DBH category by the “tree per acre” multiplier (*TPA), the average of each DBH category.  TPP *(times)TPA equals taps per acre for that DBH category.  Sum a row of TPA= to estimate taps/acre.  

Finally, sum and calculate average for all the points to find the average taps per acre to the section of sugarbush included in this evaluation.  For example from one plot point as you rotate the full 360 degrees you identify 2 trees between 10 and 11.9 DBH, 5 trees 12-13.9 DBH and one tree 18-19.9 DBH.  In the DBH category 10-11.9 place two dots under that category and beside the TTP box.  

Multiply this by the 15.2  and list 30.4 in the TPA (Taps per acre) box.  Under 12-13.9 mark 5 dots in the TPP line and multiply the 10.8 times 5 and list 54 in the TPA box. Under 18-19.9 place one dot and multiply times the 5.1 multiplier and list 5.1 in the TPA box.  

Add all the TPA boxes for an estimate of 89.5 taps per acre at this point.  Continue with 2 to 4 more points in similar woods to get a more complete estimate.  

March 2013