Question about tree growth - dark/light growth rings

[Tetsuaiga]

I read recently that the summer growth is the dark band and light wood is I presume spring and autumn, in winter tree stops growing entirely?

What I find odd is that the dark band is thinner than the light wood. Why is this the case? Especially if a tree grows most during the summer, that's an old assumption i've had but don't really know how much that's the case.


Maybe I have this all confused so if anyone can help that wouild be nice.

 

[wizard]

http://www.microscopy-uk.org.uk/mag...croscopy-uk.org.uk/mag/artjan02/treering.html

 

[Tetsuaiga]

I suppose i'll have to conclude that trees actually grow more in spring than summer. That's obviously the case with the leaves, but I didn't know it was also the case for the trunk itself.

I wonder what change takes place that actually causes the tree to transition from creating light cells to dark.

 

[gregmcateer]

http://www.microscopy-uk.org.uk/mag...croscopy-uk.org.uk/mag/artjan02/treering.html

Interesting site. Thanks for posting it up

 

[Sgian Dubh]

I suppose i'll have to conclude that trees actually grow more in spring than summer. That's obviously the case with the leaves, but I didn't know it was also the case for the trunk itself.

Not necessarily. The mass of tissue laid down during the spring and summer growth period may actually be similar. It could simply be that the spring growth appears bulkier because of its more open texture, whereas the summer wood is denser and closer packed. This is more likely to be the case I suspect in parts of the world with distinctive growing and dormant seasons, e.g., temperate regions and monsoon regions, whereas tropical regions are more likely to have varied but favourable growing conditions all year round, and trees often feature less distinct seasonal differences in growth patterns - they are often be diffuse porous (e.g., mahogany) rather than ring porous (e.g., European oak).

I wonder what change takes place that actually causes the tree to transition from creating light cells to dark.

I strongly suspect the signals are chemical, triggered (in temperate regions for example) by such factors as increasing daylight hours and general rising temperatures; and even perhaps rainfall patterns, as well as animal, fungal, insect and bird activity which may trigger chemical signals, etc. Slainte.

 

[GLFaria]

http://www.microscopy-uk.org.uk/mag...croscopy-uk.org.uk/mag/artjan02/treering.html

Thank you for the link. It helps clarify some notions I had.

 

[nicguthrie]

Interestingly, I checked some facts to answer this and found that my own long-held beleifs about what was going on, were totally wrong. The rings are formed as in winter (in our northern climate) the growth shuts down totally, to protect the tree from frost, and the rest of the year, the growing conditions, water and sunlight amounts etc vary the growth by season. I've got some Siberian larch which holds a fantastic seasonal record of it's growth, with rings varying from several mm accross to so close together that you can barely make them out (cold, wet, dark years where little growth happened)

The best, non-science-boffin type site I could find in a short search for you was this one, that explains it all in quite some detail.

https://www.theforestacademy.com/tree-knowledge/annual-growth-rings/

Hope it helps.

Nic.

 

[Tetsuaiga]

Thanks for your input Sgian.

 

[glynster]

A moment of epiphany for me was many years ago when my partner bought one of those mini bamboos from IKEA - technically a grass not a wood it should be said. It must have been 4 inches when we bought it. It was put in a jar of water on the turn of the stairs and only and a couple of years later it was 9 feet tall and a "good" inch thick. What amazed me was where had all of that solid matter come from when we'd only ever fed it water very rarely - then hit home that it had literally turned the carbon in the air that we'd breathed out into solid matter en masse. Makes you realise that trees are amazing things in that they are made more from particles from air more than they are from matter from the earth they stand in. 100% carbon neutral - a tree, even when burnt, only gives out the carbon it consumed in its life. I know we all know that but to observe it and see the solidity of it - to me anyway - seemed like a mini-miracle.