Tree Answers

by Deb on September 23, 2011


How did you do? Is some trivia to start you off on a Friday working for you? If you want the questions, close your eyes and click.

1.     Tree ring dating is simple in theory but complicated in practice. The basis of it is that trees in highly seasonal climates have growth spurts in warm weather and slow to a halt in cold weather. These give you the distinctive yearly ring with a wider part for the summer growth and thinner, denser part for the winter growth.


Photo courtesy of Arnold Paul

Tree growth is quite sensitive and is different year to year. If something happens like a cold summer that slows growth down, that ring will be thinner. Over many years there will be a pattern of thick and thin rings. Looking at lots of trees over a wide area produces a consistent pattern that can be used to work out dates. It will also pick up major global events like volcanic eruptions that put lots of dust into the atmosphere. Usually a tree does not need to be cut down, there are special drills used to take a core.

When a new piece of wood is found that has enough rings to find a pattern, it can be compared to the reference patterns to see where it fits. This has been done with logs used in furniture and building and can date them to the exact year the tree was cut down. It has also been done with logs found preserved in peat bogs and extended the pattern further back in time.

Boggy conditions preserve wood because there are no decomposers to break it down. This not only happens naturally, there are some cultures that have thrown wooden objects such as canoes and even coffins into bogs. If some of the tree rings match the earliest parts of the patterns from living trees, they can extend the pattern to cover their early years as well. The dendrochronology calendar for some areas goes back about 9000 years. dendrochronology

2.     Trees are specifically trees because they have wood. I know shrubs and bushes have wood too, but they are basically the same type of plants as trees. Often picking a plant as one or the other is subjective, like in the picture. Plants often come with varieties that grow as trees or bushes, which is really just a shorthand way of saying ‘tall woody plant’ and ‘spreading woody plant.’


Is this a large bush or a small tree?

3.     Fruit is the part that contains the seeds, which is why tomatoes are a fruit. They are not always fleshy and enticing, and they have two main  jobs.

Firstly they protect the seeds while they are developing, which is why unripe fruit is generally much harder.

Secondly they help seed dispersal, either by the way they open and spread the seeds or by getting animals to eat them. Having animals eat them does lots of different things – it spreads the seeds further, plants them in their own patch of fertiliser, and sometimes is necessary for them to germinate. Seeds often have a thick skin that needs to be broken down for the embryo to get out, going through the acid and other digestive juices plus being smashed around can do this. tomato

4.     A selection of records from Guinness World Records and other places:

  • The oldest surviving species of tree is the Gingko biloba which first appeared 160 million years ago (with the dinosaurs) and is still around today.
  • The oldest tree ever recorded was a Bristlecone pine from the US, which is believed to be around 5,200 years old.
  • For something a bit different, a single tree gave five fruits, apricot, cherry, nectarine, plum and peach. They were grafted into one tree in 2000.
  • The title of World’s Tallest Tree keeps changing as people find new trees in remote wilderness areas. Currently it is somewhere in the Redwood National Park in the US and is over 115m tall. The most accurate way to measure a tree is to climb it and drop a tape measure down, the video below was taken by one of the scientists doing it.
  • The Prison Tree – not technically a record, but a piece of Australian tree history. Boab trees in the Kimberley have large, often rounded trunks that can be hollowed out and still live. This particular boab near Derby was used as an overnight lockup when transporting Aboriginal prisoners. There is a narrow opening on one side and it opens out to make a large room, chained prisoners would be put inside and the opening blocked. It’s still alive and you can see inside, although you can’t get in now to protect it from damage. When I was a kid you could still go in and we have photos of us inside.

    prison tree

    Photo courtesy of Nachoman-au

5.     The beautiful red leaves. Caused by approaching winter. There are two parts to answering ‘why?’

Firstly, why do they die and fall off? Simple answer, snow. The lovely colours are pretty much limited to those areas of the world where it snows, and the rest of us have green, growing trees the whole year round. In places where it snows winters are too cold for trees and they hibernate. Leaves take energy to maintain and can cause damage to the tree by catching too much snow or wind and breaking branches. So the simple answer is to lose them and start again when it gets warm.

Now the colour. Leaves are usually green because of chlorophyll. During photosynthesis it is used up, and over autumn deciduous trees stop producing it. This means the other chemicals in the leaves become visible, mostly carotenoids (yellow and orange) and anthocyanins (red and purple). Anthocyanins are often used in leaves to protect them from UV damage by absorbing it. This is why young leaves often have a reddish tinge. In the case of Autumn, they are produced when the chlorophyll starts to break down, probably to protect the leaf and get the last bit of use out of it before it falls off.

And just because they’re gorgeous, here’s a how-to on make Fairies with beautiful red leaf dresses.

The video of climbing the world’s (current) tallest tree. Enjoy the fascinating view.

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{ 3 comments… read them below or add one }

Stephan Hilson September 23, 2011 at 12:45 pm

I remember that I learn how to distinguish the age of trees through its rings. But it is interesting that I’ve read about the gingko biloba. I couldn’t imagine that there is a specie, which is already existed at the age of dinosaurs. Thanks for the sharing the link of how to make Fairies with beautiful red leaf dresses, which I am going to check later.
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Deb September 23, 2011 at 1:01 pm

I know, I keep thinking they must have it wrong. Especially because the average span of an animal species is 5 million years, for one species to last 160 million years doesn’t sound right! But then you hear Bristlecone pines can live thousands of years, so maybe it’s the same number of generations.


Tricia September 25, 2011 at 9:49 am

I don’t think i’d known about the seasonal component to tree rings (or if I did, i’d forgoten). Thanks fro the reminder.

That video of climbing the worlds highest tree was amazing. How sad that there’s only 1% of those forests left.

An easy way to pick trees and shrubs is that trees mostly have a single trunk (but not always e.g.mallee) and are more than 5m high. I recently had fun teaching Little Eco how to work out the height of a tree. there’s some simple instructions here: We used the eye and fingers method.
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