Hi Brandon,
Sorry it took a few days to get back to you. I was away and only had my phone to check email and MapleTrader, so didn't feel like responding in that way.
First I'd like to say that the original question is very important and interesting. Sugarmakers know that there are two seasons....fall and spring. But only the spring season has been utilized. As the climate warms (regardless of why), the season is getting compressed at the ends, with the two season peaks moving closer together. Whether it is possible to tap in the fall and have a viable taphole in the spring is a question that I've pondered and mentioned to many people for several years now, but just haven't yet had the time or funding to do (there are always more projects to do than time or resources allow). I would be very interested in doing this study across a geographical gradient that included southern sites. I'm really only interested in doing research if it is done properly and can answer questions with some degree of certainty....and if it can be completed before I retire.
In terms of the original message you conveyed, several posters have noted the same issues that I had. Chief among these is that there was really no adequate control (for comparison purposes). When we do research, the first thing we do is to make sure we have strong controls. This not only allows us to detect smaller changes, but also allows us to isolate the single variable causing the response. In addition, it allows us to say statistically (within a certain degree of confidence) whether what we observe is likely to be real and caused by the variable in question, occurred simply due to chance, or was within the error of the observation. It doesn't seem like those factors were included in your "research." Please don't misunderstand me....I think the goal of your project was interesting and worthy of study, and that the results are interesting, but I object to calling this work "research" and don't place a lot of value on it for decision-making purposes.
When doing "research", having a good and examinable question is the first thing. In your case, I think you probably had a good question (does "retapping" or "reaming") help? However, there are some questions of definitions and semantics. Reaming usually refers to tapping with a wider bit, and may or may not include drilling deeper. Retapping is putting a new hole in the tree. What you seem to have done is "reaming" with a deeper taphole, not "retapping."
Why is having a good control important? First, you need to have something to compare to. Comparing one sugarbush to another isn't a decent control. Perhaps if you have 15 of one type and 15 of another type it would work, but what you've done is more like comparing apples and shoe brushes. Why? First, the sites were tapped at different times. They were also tapped with different spouts in terms of color and in terms of composition -- one seems to have been a black nylon and one is a clear or light-colored polycarbonate. Black spouts will always outperform light-colored spouts in cold years and perform much worse in hot sunny seasons. Polycarbonate tends to stick better in the tree and thus hold vacuum better. Either of those factors could contribute somewhat to the differences you observed and seemed to ascribe solely to the fact that one was a CV and the other was not. Were they all tapped in the same orientation? Were the droplines all the same age and composition and had been cleaned in the same way by the same people? Were all the taps made at the same height? Same tappers doing the work? Same tapping bit at the same depth? Same vacuum? Same releasers? Same diameter trees? As you know, 1" Hg difference in vacuum means 5-7% difference in sap yield. Similarly, 1" difference in diameter means about 2 gal difference in sap production, and does also affect sugar content? Sounds like you had some producers on pumped vacuum and some on natural vacuum? Was vacuum continuously measured so you know what it was? Was leak checking at each of the sites EXACTLY the same? When we do research, we ensure that as many things as we can possibly control are all identical. Otherwise it is quite easy to see a 25% difference in sap yield, but have it NOT be statistically significant due to the high number of factors affecting sap yield and the degree of variability we find. Unfortunately doing GOOD research is neither easy, nor cheap.
You also don't have good control even within the site that used CVs. You changed the parameters in the entire site halfway through. How much more would those taps have run if you hadn't reamed? You might think they'd stopped, but you will never really know since it wasn't measured. Was it just poor weather that caused the reduced flow, or was it clogging? You cannot tell. The better approach would have been to have two (or better yet, a bunch of) separate lines at that site and reamed half of them and not reamed the other half. Then you'd have a good idea of how that one factor (reaming vs not reaming) affected sap yield. Unfortunately, doing that might have meant a loss in sap for the producer. That is why dedicated research centers are important -- we can do things that might cost us sap production because the value for us in in the research, so we don't need to make those sorts of compromises and jeopardize doing good research.
There are undoubtedly MANY possible factors that contributed to the results you found. I don't think you can really subscribe them to any one thing. Moreover, you suggest that this was an unusually warm season (warmest winter on record). That is why GOOD research also takes time. We typically don't like to talk about one year worth of results....and especially don't like to talk about them or more firm conclusions if it is an unusual year until we get some replication. Replication is another important facet of GOOD research. This is both replication in terms of experimental units (number of trees or number of study sites depending upon how the experiment is set up) and replication in terms of whether or not we observe the same results from one season to the next (we all know that each maple season is a little different from prior years). It appears to me that you have neither type of replication....again, why I don't really consider your project to be "research."
Finally, as others have pointed out, you are a dealer for a company that doesn't sell CVs. I have no problem with that, but it is worth mentioning that all the actual studies that have been done by actual researchers have shown that CVs do what it is claimed they do. CDL sponsored two studies by Centre Acer. The first found no difference in yield, but the study had serious design flaws. When repeated correctly, they did find a significant positive effect of CVs. Admittedly, there hasn't been any research done in the southern fringe of maple production, so the inference may not extend to that area completely for unknown reasons. There's no reason to believe that is true, but we cannot discount it since it hasn't been actually studied there (limitations of inference is another important factor in scientific research).
Getting more sap is really not the important question. We know some things that could be done that would get HUGE amounts of sap....but they aren't practical or economical to do in the real world. What is most important to most producers is getting the highest net profit. If you repeat your project, it might be interesting to also factor in the time and cost of "reaming" into the equation.
So again, your results are interesting....just not what I consider "research" and certainly don't definitively answer any question. Don't take that as an insult....not at all my intention. GOOD science isn't cheap or easy and understanding all the things involved in doing GOOD field research takes a lot of training and experience to accomplish. I would be very happy to chat with you about how to do a more appropriate study and perhaps in cooperating with Dr. Mike Rechlin (note spelling of his name) to do some research if we can find funding to do so.
Cheers.
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Originally Posted by mountainvan
