Tree rings: what does this mean?

[Loiseau]

A week ago I had a few trees pruned or cut down around the periphery of my garden.

The tree-fellers/fellas cut the trunks up into manageable chunks for firewood, so I look forward to some warm winters ahead...

I noticed that the oaks they cut down had a different-coloured core from the outer part, and wondered what this could be due to.

[IMG]http://i159.photobucket.com/albums/t127/loiseau85/treering_zps31ef250a.jpg[/IMG]

The slice above is about 18cm in diameter.  It looks as if the inner rings are narrower than the outer rings.  Does this bear out my theory that we have been having much wetter summers in the Vendée for the last decade?

Angela

[Elle Gee]

I am no expert, Angela, but was once told that distinct differences like this are fire scars. Might be the case here?

[Frederick]

Angela  you are right :    Found this for you

When conditions encourage growth, a tree adds extra tissue and produces a thick ring. In a discouraging year, growth is slowed and the tree produces a thin ring. Much of the variation in tree rings is due to variations year-to-year in:

• Higher springtime temperature. If spring starts early, the growing season is likely to be longer than usual, causing a tree to have a wider ring.
• Lower springtime temperature. A late spring is likely to shorten the growing season, causing a tree to have a narrower tree ring.
• Abundant rainfall increases growth, producing a wider ring.
• Drought decreases growth, producing a narrower ring.
• Species of tree do differ in their response to weather changes. One might respond strongly to changes in overall rainfall, another might be more sensitive to the amount of rain during the late summer, and another to a temperature change that alters the length of the growing season.
• Crowding from neighboring trees. This causes a series of narrow rings. Crowding is suspected when the series of narrow rings is more than three, because droughts are usually only one to three years.
• If the rings are narrow on one side of a tree with wide rings on the other, the tree was crowded on the side of the tree where the rings are narrow.
• A series of many narrow rings followed immediately by wide rings probably means that an encroaching neighbor died, releasing the crowded tree into a growth spurt.
• Fire scars suggest past forest fires. The number of annual rings between fire scars shows the period between fires.
• Scars due to insect plagues indicate insect infestations.

[Loiseau]

Wow, thanks Frederick!

That's very interesting, and does indeed bear out my theory.

Fire is not an issue, and they are not trees that have been crowded at all, just ones that grew in the hedgerow with a huge open field on one side, and my garden on the other.

Angela