Tuesday 26 June 2007

Self-Pruning Trees

My son asked why the branches of some trees seem to fall off without any reason.

I found the following quote on the National Association of Forest Industries website:
The self-pruning habit can be a disadvantage in a town, and the choice and positioning of some species need careful planning. The limbs of some eucalypt species are dropped progressively from the tree by a natural process: a fungus weakens the base of the limbs and the growth of the stem forces the branch to break off at that point. The limbs have a habit of dropping without warning on calm, hot days and for this reason many Australians are wary of picnicking or camping under large, old eucalypts. Bushmen refer to these limbs as 'widow makers'.


I also found some research articles on the same topic. John H. Schaffnew says in his paper that some trees develop "brittle zones" and "cleavage planes", which form weak spots in the branches. When the limb grows, it causes these branches to break off. Brittle zones and cleavage planes exist in deciduous plants which allows them to shed their leaves in winter. They also exist in fruits, which is why we can pluck a strawberry, or an orange and not take off half the branch as well.

Sunday 17 June 2007

End of an Era

It's the end of an era, the demolition of my old house. It was originally built as temporary housing in the early 1950's for people returning home from the war. Many houses in Western Australia were built with the same design. My father-in-law's house is a mirror image, except that he has extended it in most directions, nearly doubling it's size.

Our neighbour has lived in her original house since it was built. She has told us about the changes in the neighbourhood, how we didn't have a road out front, only a dirt track. The mail man, milkman, ice man, and veggie man all delivered their goods to the road at the top of the dirt track, and all the people used to walk up to the road to collect their mail and things. Out to the east was a dairy, where the cows grazed in the paddocks. Now there's two major highways. Out to the west was a pine plantation, now there's a university and a retirement village.

Even the last 15 years that we have been there, we have seen changes - our neighbour's house is now one of the very few original houses left. All the other original houses have been knocked down and converted into units.

Now all that's left of this house is a pile of wood, and the brickwork chimney and laundry. The end of an innings.