This evening I went with a couple of friends to the Royal Society's Summer Science Exhibition 2007 which is, according to my friend Lena, the highlight of the geek-calendar. 
http://www.summerscience.org.uk 

It's open until the 5th of July but the first and second nights (ie tonight and tomorrow it opens late, until 9pm) - there are 20+ exhibits featuring anything from the science / technology world.

Last year when I went I had recently started finding out a bit more about trees and so went straight to "The Breathing Forest (2006)" http://www.royalsoc.ac.uk/exhibit.asp?id=4673 (and then a few days later I watched a day of ski and canoe making and was hooked!) and this year was no different. 

We first went to the "Life at the top" exhibit which was all about the rainforest canopy and the fact that loads of earthworms are lurking at the tops of trees, in plants called epiphytes.  After chatting to all of the scientists there about their work we left with a mini epiphyte of our own which I'm really going to try not to kill! The smell of the large plants they'd brought in for the exhibit was glorious and they were covered in a sort of mossy stuff (bit spaghnum-y) which is able to maintain a cooler and wetter environment for local creatures than the tops of the trees where the sun bakes things a bit.

The trees are a bit massive apparently and the equipment used in logging (along with the transport roads) is probably an order of magnitude beyond what would be found here in the UK, fortunately some of the governments in the area seem keen to protect areas from too much logging but I expect others on here could give additional insight on that!
http://www.summerscience.org.uk/07/node/19

Staying with woodland we then went to "Listen to what the trees are saying..." exhibit where a stack of logs was tied up and the ends lettered A - F.  Here, the goal was to whack each log with a hammer and determine by ear whether or not the wood was good for construction purposes.  If anyone's reading this I'm sure you'd be very proud to know that I did ask "what wood is it?" and it was two types of spruce (Sitka and Norway). 

The higher the pitch the better the wood is (because it's stiffer and less likely to sag and so better for the construction industry) and I got a free mug for picking out the better logs :-] 

They also have a couple of high-tech devices which do this for you (which is helpful when you're dealing with more than 6 trees!) as these measure the speed at which the sound wave travels to the end of the log and back again.  The second system involves two devices embedded just below the bark at a known distance apart (the machines actually bounce an infrared beam at each other to confirm this) and then you whack one end and it measures the speed at which the sound wave travels from one device to the other and back again; this is related to the stiffness of the wood.  I've already forgotten the details (!) but I'd assume that the more dense the wood the faster the sound wave (and so a fast speed would tell you that you had good dense wood).
http://www.summerscience.org.uk/07/node/31

Then we went to hear marine scientist Justin Hall-Spencer talk about his (and co-workers) discoveries of coral reefs in the northeast Atlantic.  He's been submerged in a small vessel near Norway looking at coral and other marine life - and we all got to handle some different types of coral and even take a piece home.  He showed some startling footage of untrawled (ie left in peace) and trawled areas and the effect this has on the coral.  It's not good! http://www.summerscience.org.uk/07/node/61

We also attempted simulated key-hole surgery, heard an almost silent aircraft land (they're trying to reduce noise pollution but I love the sound of aircraft engines so had mixed feelings about that one!), learned about language in primates in Uganda and had a great time for nowt :-)

Jo