I've played with Gps units for work, ranging from $100 handhelds and $20k rtk units accurate to an inch or two. I'm also a bit of a statistics nerd, So I will chime in on the accuracy ratings of some of these units.

A standard handheld or smartphone is, at best, accurate to maybe 12 ft or so. The latitude/longitude that recorded is not the *true* location, rather an estimate. The true location of the tree you mapped occurs in some circle located around the recorded point. The way these low end units are rated, the "true location" Will fall within a 12 ft circle around the recorded point 50% of the time. Depending on what you want, that is not very good. But for mapping trails or "the good fishing hole is here", not bad.

For mapping individual trees at an accuracy that does a good job of true mapping, you want something in "sub meter" class (roughly 3.28 ft). We just got a new one at work, it was $2k. Nice unit, very econimical, as most sub meter run in the $7k range. That said, I get about 2 meter accuracy under trees, so 6 ft. It uses my smartphone as the data recorder and user interface, and I use MapIt. That is a great app if you want to play with it. It is free.

All that said, I don't really see the advantage of mapping individual trees for a syrup production. I could see it useful for mapping a new section of woods to record where the denser stand of maples are. But for that purpose, a phone is plenty accurate.

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