THE commodity boom of the past seven years has led to all sorts of weird happenings around the world. There have been the tortilla riots in Mexico, sparked by the rising price of corn, and the theft of manhole covers all over the UK as well as the US for sale as scrap metal.

Then there was the disappearance of a large sculpture from the Henry Moore Garden in Hertfordshire, apparently for the same reason. It was last seen being driven through Harlow strapped to the back of a lorry in late 2005.

More recently, we heard of the residents of Tokyo waking up to find swings and seesaws missing from their playgrounds, taken, or so we imagine, to be shipped from Yokohama to Beijing to help alleviate the Olympics-induced steel shortage.

Then, only a few weeks ago, there were reports of Shinto priests in Kyoto expressing regular outrage over the fact that tiles from the metal roofs of their temples keep vanishing.

But last month we heard of something that is going to hit middle England closer to home. It seems that Chinese demand for yet another commodity – timber – has started to push up the price of some of our national staples – namely wooden garden chairs and decking.

According to the Office of National Statistics, the cost of wood products is now rising at about 13%, its highest rate for nine years. This makes sense. By some forecasts, China will have to build 50 cities the size of London in the next 20 years to house its rising urban population – and building cities uses up a lot of timber, as do their populations. The new middle classes of Asia need wood for all the same things the middle classes of the West do. They need pallets, cardboard boxes, furniture, books, newspapers, and, depending on the fashions of the day, wooden jewellery and shoes just as much as the rest of us.

Chinese lumber demand doubled between 2000 and 2003, and is forecast to rise by another 30% in the next five years or so.

China is already the largest importer of both soft and hard woods in the world, so even if that forecast ends up being only half true we are still talking about an awful lot of trees.

Demand is also coming from the rest of emerging Asia and, closer to home, from our new interest in green energy; low-grade wood, burnt as chips or pellets, is still a reasonably cheap bio fuel.

The upshot of all this is that timber has a supply-demand dynamic similar to that of many of the other commodities I have written about here over the past few years: rapacious demand is meeting limited supply (most of the easy-to-get trees around the world have already come down). That, in turn, means prices are likely to keep going up.

The good news for investors is that they could have a long way to go. While UK prices have risen some 11% in the past three years (according to the FIM Timber Index) they have done so from a very low base; today, even as practically every other asset class in the world is hitting new highs, timber prices are still nearly 50% below their 1996 levels. The same is true in the US, where prices have started to rise properly only in the past few years.

As its fans (including pop singer Britney Spears, who reportedly bought over $3m worth of forest in Louisiana a few years ago) often point out, timber doesn’t actually need to rise in price to make it a good investment. Trees naturally increase in size and become more valuable over time. Unlike other perishable commodities, they can also be “stored” in bad markets and sold off as and when they are needed.

However, to my mind the best thing about timber investments is that so far they have shown a very low correlation to other markets – in other words, they rarely move in tandem.

Note that during the horrible bear market that ravaged stock-market investors in the 1960s and 1970s, timber investors in the United States never had a losing year.

If you are nervous about stock markets in 2007 and 2008 – and there is good reason to be – there probably aren’t many better places to put your money.

If you want to invest in timber in the UK, your choices – beyond stockpiling B&Q products – are fairly limited. You can, of course, buy woodland directly, something that many think worth it for the tax benefits alone. Commercially managed woodland is free of inheritance tax after two years and you pay no tax on income derived from it. However, while it will probably turn out to be an excellent buy, you need to invest a large amount of money to get the scale needed to make it a worthwhile, stand-alone investment.

Otherwise, FIM (www. fimltd.co.uk) manages timber funds with a minimum investment of £20,000 (although the fees on them seem high) and the brave might look to invest via the stock market by buying into the recently listed Cambium. The firm raised just over £100m on AIM last month, and has recently secured an option on its first forestry property in New South Wales.

Finally, if you are willing to look to the US, there are several pure-timber companies listed there. One is Plum Creek Timber, which owns forest in more than a dozen different states, and the other Rayonier which, while smaller, still owns more than 2m acres of forest. Both have reasonable yields of around 4%.

Merryn Somerset Webb is a former stockbroker and now editor of Money Week. Her views are personal and investors should always seek professional advice