I work at a hobby where we chase single growth rings on trees for a smooth unviolated back or our archery bows. We are very familiar with spring growth or early wood and late wood. Something else we debate about is lunar rings visible within the latewood of the tree, thin lighter colored layers that often seem to correspond to the moons of a growing season.
Can lunar actvity affect the growth cycles of a tree?These rings do not always show up but in some trees are very prominent. Is it possible that the full moon could raise the water table just enough for a tree that was marginal. The thing that might take away from this theory is that a particular tree will show these additional rings nearly every year of its life.
I think you would be drawing a long bow to suggest direct influence of the moon. Tides are daily, and the spring tides occur at full and new moon - so you have a 2 week cycle, not once a month higher than usual tides. So that one probably doesn’t hold water.
Where you might find some possible causation is in the night activity of some animals. It might be that some trees become stressed by an increase in insect activity associated with a full moon.
Working out a meaningful correlation with the sub-rings and a lunar cycle is going to be pretty hard. I would be more inclined to look to the weather records and see if cycles of temperature had any correlation. Even then, the difficulty in placing a precise date on a sub-ring will make things difficult at best. But a decade odd of weather records and a decade of rings in a tree would be a good start.
I don’t know much about tree rings, but I agree with Francis Vaughan - it would be difficult to establish a connection with lunar cycles.
However, I suppose the next question to ask is: where (what latitude) are these trees found with the sub-rings? Tree rings are most easily distinguished in the high latitudes, since each growing season is strongly distinct from the intervening winters. In the tropics, multiple/continuous growing seasons make it difficult to distinguish tree rings, and in some tropical environments with no or little distinction between wet and dry seasons, tree rings can only be distinguished with esoteric techniques like UV-microscopy.
So, what latitude are these trees at? Fainter rings may actually be poorly-distinguished growing seasons of a year while the stronger rings may be years with dramatic rainfall or warmth, especially if you’re in a subtropical area or similar latitude.
The particular tree we are looking at is from Kansas,
I recall reading that in very well-preserved stromatolites, one can identify daily layers and thinner lunar layers when there is a full moon. These are valuable for verifying the length of the year and month in ancient times.
Never heard anything like that for modern trees, though.
Huh. Well, Kansas definitely doesn’t count as subtropical. Is there any reason to believe these sub-rings are more related to the moon than to rainfall and temperature, though? I’m having trouble seeing any plausible mechanism there.
no
the moon has no effect on growing trees. it’s light is too weak to cause photosynthesis
MAYBE higher or lower tides could effect trees RIGHT ON THE SHORES of coasts, but then you’d be limited to trees in those locations, that can grow there, so you’re only talking willows on brackish rivers (like the Hudson) or mangroves.
Think about it. If you’ve got a pond in your backyard, how much is it affected by the tides. By an amount too small to measure, other effects like wind and evaporation dwarf the effects of the tide on a small body of water. Even lakes as big as the Great Lakes have tides less than two inches, which can easily be swamped by winds pushing water to one side of the lake or another.
Tides do not affect the water table.
If there is a correlation between tree growth and the lunar cycle there would have to be some other explanation. A more likely explanation is that the variations you’re seeing in the wood between the annual growth rings are not correlated with lunar cycles at all, and you’re seeing different growth rates over the growign season due to rainfall or temperature or herbivory.
I was thinking in terms of large water tables that might stretch several hundred miles, but even then I still tend to agree with what you are saying. This has been one of those ongoing discussion amoung bow makers for decades.