Thread: Growth Rings

Interesting point.

To my tired eyes neither has distinct growth rings.

I see the growth rings in such species as the conifers being distinct. Have a good look at Oregon (aka Douglas Fir) and Baltic pine and you will see what distinct growth rings are.

I think the blurring of the seasons in Australia makes it harder to define the growth ring boundaries in our native species.

Growth rings show the distinction between different growth rates that usually represent the wet and dry periods. Acacias and other fine grained hardwoods do make it more difficult but they can be seen. What makes it even harder are places like the Gold Coast where we often don't have either a winter/summer nor the wet/dry seasons of other areas of Aus but a mixture of both. It can often be wet all year long, or dry or year long, depending on the longer term cycles throughout the decades.

Well, I think I may have been totally misinterpreting the whole rings issue.


The area marked with a number 1 is what I thought would be the Heartwood.
The strip marked with a number 2 would be the Sapwood.


Then I have marked what I thought would be the Early Wood and the Late Wood in what I thought would be the rings.


Give me the Flowers and the Fruits. They are much easier.


This is almost as confusing as the leaves.


Attached is a pic of a Douglas Fir ring. Yes, the rings are very clear and distinct. The Early Wood and the Late Wood is quite clear, but the Heartwood is not. I can see a slightly darker central section that extends out to about 2/3 of the way to the edge. Would that be the Heartwood with the rest being the Sapwood? There doesn't seem to be much difference - in appearance at least.


Thanks
darrell

The usual convention is that the heartwood has additional lignin and waste products so is the darker section of the timber. In other words, yes, the darker section is the heartwood. The terms early wood and late wood are usually applied to northern hemisphere conifers, rather than Australian hardwoods because they have such distict seasons of summer and winter. Australian seasons are quite different as many plants have two growth seasons a year, spring and autumn, and they do not grow in summer and winter. As such, many, perhaps most Australian trees actually have two growth rings in a good year. However, they can have no growth rings in a drought year so dendrchronology (telling the age of a tree from growth rings) does not work well in Aus. Tasmania may be the exception as the seasons are much more distinct.


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