tropical trees

[jamie]

question that has confussed me and my boss. brought up when we were asked to cut a few old railway sleapers (the saw was needing a rub so we said yes) and ive been told that many sleapers are imported.

Do trees in areas such as the rainforest and such like where there are no distinct summer / winter periods have annual rings like those from temperate regions.

to the best of my knowledge the environment in the rainforests is pretty similar throughout the year (with plants flowering and fruiting throughout the year).

jamie

 

[Proarbor]

Jamie I'm not sure about trees from the tropics but with Australian Eucs, you can not determine age from the rings as they are growth season rings not annual rings. If conditions are right eucs will have multiple growth seasons in a year. Season is'nt the right word but i'm having a mind blank !!!!!

 

[Stumper]

Many Tropical hardwoods do not have discernible growth rings. Others have seasonal growth rings based upon wet and dry periods. Have you observed lunar rings in fast growing temperate species? (I don't mean rings around the moon It is possible to see the lunar/tidal cycle reflected in the growth laid down in some cases.

 

[murphy4trees]

I think Graham called them free-grain trees... supposedly don't hold together too well... He talked about sections of big trees ripping the roots up on barber chairs etc..

 

[rumination]

Proarbor and Stumper pretty much got it covered. Some tropical trees have no discernible growth rings. Some trees do have rings, but they are not annual rings. Many trees will put on two or even three rings in one year.

I was actually thinking about this today when I was cutting down a 30 ft albizia. The tree was probably 2-4 years old but there were 8-10 faint rings visible on the stump.

I believe that the amount of growth rings is directly correlated to the environmental conditions. Where I am the weather is fairly constant with heavy rainfall yearround, so the trees can put on two or more growth spurts a year. It is hard to tell. In other areas of the tropics there are clearly defined wet and dry seasons (sometimes two of each in a year) and so the tree would put a growth ring for each rainy season. In Africa baobab trees can go for more that a year or two without leafing out at all if there is a drought and so might not form a visible growth ring for that time period.