Calculating the best tapping date

[Sugar Bear]

Sorry if I'm being obtuse...you're suggesting sap flow is more determined by photoperiod REGARDLESS of temp...but then acknowledge that temp. obviously plays a significant role? It can't do both...play no role and play a significant role. Again, sorry if I am reading you wrong.

No that is not what I am trying to suggest. Poorly written on my part.

I am suggesting that sap flow or peak sap flow of the season is ALSO determined by daylight length and/or daylight angle in addition to ideal temperatures or specific weather, which of course, as we all know are required for profuse sap flow.

And perhaps the daylight length/daylight angle is more of a factor then we recognize, or it is believed to be.

Again ...

And perhaps this is why in a year like this, when we had hardly a single iota of frost in the ground all year, and I taped on Feb 6th, I still got my best sap flow, on these same taps, in the second week of March, even though many opportunistic sap flow days appeared in February. Albeit there were some very warm shut down periods in February, but those came after the opportunistic sap flow days in February.

Crazy warm winter we had but POOF ... like magic ... best sap flow in the first two weeks of March ... yet again. And yet on taps already 4 weeks old. And yet on taps that had ample opportunity to peak out in the second week of February just hours after they were tapped with no hard freeze up in the ground at that time.

So if that ( the above theory is true ) it makes all the more sense to find that ideal period (For my tapping range it seems to be March 1 through March 14) and tap no more than two or three weeks prior to that date period. And not drive oneself crazy year after year with when I should tap. This year I did three weeks prior instead of two weeks prior.

AND OF COURSE THIS ASSUMES YOU ARE SMALL GAME AND DONT HAVE TO START TAPPING IN AUGUST AND DON'T HAVE TO PAY A BUNCH OF SALARIES! Your own included.

[DrTimPerkins]

I am suggesting that sap flow or peak sap flow of the season is ALSO determined by daylight length and/or daylight angle in addition to ideal temperatures or specific weather, which of course, as we all know are required for profuse sap flow.

And perhaps the daylight length/daylight angle is more of a factor than we recognize, or it is believed to be.

There is ZERO evidence that day length/photoperiod/light angle have ANY effect on sap flow OTHER than how they affect tree temperature. Wood temperature is the dominant driving factor in sap flow.

Sap flow, growth, leaf drop and dormancy are all physiological functions that are well understood. The drivers and interrelationships are not terribly strong among this group. Sap will flow in wood vessels whenever driving forces are present. Those driving forces are dictated almost entirely by wood temperature.

[Sugar Bear]

There is ZERO evidence that day length/photoperiod/light angle have ANY effect on sap flow OTHER than how they affect tree temperature. Wood temperature is the dominant driving factor in sap flow.

Sap flow, growth, leaf drop and dormancy are all physiological functions that are well understood. The drivers and interrelationships are not terribly strong among this group. Sap will flow in wood vessels whenever driving forces are present. Those driving forces are dictated almost entirely by wood temperature.

So are you saying there is no evidence that sunlight effects sap flow within the stem any other way then thermally over the course of a sap flow season. Correct?

[Swingpure]

So are you're saying there is no evidence that sunlight effects sap flow within the stem any other way then thermally over the course of a sap flow season. Correct?

Maybe another way of asking it, does sunlight affect wood temperature?

[DrTimPerkins]

So are you saying there is no evidence that sunlight effects sap flow within the stem any other way then thermally over the course of a sap flow season. Correct?

If we are talking solely about the physiology of SAP FLOW, then the vast majority of the influence is wood temperature. The vessel elements and fibers in the wood are DEAD while functional, so those other things have no way to influence SAP FLOW. Anything that affects wood temperature (sunlight, rain, snow, wind) is an indirect effect (they can influence wood temperature, which then influences sap flow). Sunlight, day length, etc. do not affect SAP FLOW except through their effects on wood temperature.

Going back more directly to the thread topic...air temperatures varies a little according to height, position, location, etc. Wood temperatures vary a great deal from one side of the tree to the other, from near the ground to the upper branches, and from a small portion of the woods to the next due to really minor changes in drainage, aspect, etc. Since the entire sap flow mechanism depends upon just the tiniest change from frozen to thawed, it is not realistic to try to predict when sap flow will occur with ANY degree of accuracy, especially from the early part of the season to the end. Weather predictions for air temperature beyond about a week aren't especially precise, and tend to revert to the mean temperatures based upon historical data. If that's the case, why not just use the same historical data to predict when tapping should start, and adjust a small and reasonable amount to account for the season.
Now if we start talking about stem sap sugar levels, dormancy, growth, fall foliage coloration, and leaf drop, then other things start to be involved as well.

[Sugar Bear]

If we are talking solely about the physiology of SAP FLOW, then the vast majority of the influence is wood temperature. The vessel elements and fibers in the wood are DEAD while functional, so those other things have no way to influence SAP FLOW. Anything that affects wood temperature (sunlight, rain, snow, wind) is an indirect effect (they can influence wood temperature, which then influences sap flow). Sunlight, day length, etc. do not affect SAP FLOW except through their effects on wood temperature.

Going back more directly to the thread topic...air temperatures varies a little according to height, position, location, etc. Wood temperatures vary a great deal from one side of the tree to the other, from near the ground to the upper branches, and from a small portion of the woods to the next due to really minor changes in drainage, aspect, etc. Since the entire sap flow mechanism depends upon just the tiniest change from frozen to thawed, it is not realistic to try to predict when sap flow will occur with ANY degree of accuracy, especially from the early part of the season to the end. Weather predictions for air temperature beyond about a week aren't especially precise, and tend to revert to the mean temperatures based upon historical data. If that's the case, why not just use the same historical data to predict when tapping should start, and adjust a small and reasonable amount to account for the season.
Now if we start talking about stem sap sugar levels, dormancy, growth, fall foliage coloration, and leaf drop, then other things start to be involved as well.

I understand and it makes sense, and it parallels my experience with my trees.

Perhaps it's that in the first two weeks of March the rays of the sun are just producing enough thermal benefit to the wood such that it always causes me to get to peak flow in that time frame.

Do you think a Red Maple might flow earlier then a Sugar Maple in the exact same aspect ( just a few feet away ) because the wood is softer and might warm up faster? I would imagine the ideal wood flow temperature is the same in both trees.