Tuesday, November 14, 2006

An end to deforestation?

A new study examining the extent of global forest stocks claims to provide some scope for optimism. By measuring timber volumes, biomass and captured carbon, not just the land area covered by trees, the study provides a deeper understanding of forest stocks and finds these indicators to be growing in many of the countries considered. The study claims this to be good news from the point of view of climate change.

However, what the map above actually reveals is that developed countries have increasing forest stock, largely due to plantations, whereas the developing regions, which contain tropical rainforest, have declining forest stocks. Unfortunately, it has been known for some time that forest land area was increasing in the developed world but declining elsewhere. It seems the same pattern emerges even when other aspects of forest stocks are considered.

From the point of view of carbon capture it may be good news that some countries have increasing forest stocks, but from the point of view of biodiversity the above distinction between developed and developing countries is anything but good news. Forest cover in the developed world is often mono-culture plantations which are rather sterile in biodiversity terms. Whereas the tropical rainforests, which are still declining, are teeming with life and have a greater density of biodoversity than anywhere on the planet.

But the study's main scope for optimism comes from the claim that countries appear to 'grow out' of deforestation. By plotting changes in forest cover against per capita income the study claims to find evidence of an inverted-U shaped relationship with increasing forest stocks in all countries with per capita incomes greater than $4,600. Such an analysis is extremely simplistic and the conclusions the authors come to should be treated with a great deal of caution. Firstly, the small number of observations mean it is not possible to control for all of the other variables that influence forest stocks. Secondly, there would only be scope for optimism if the positive aforestation in the developed world were equivalent in quality to the lost forest stocks in the developing world. That is, we should be talking about the same 'good' over the entire range of the inverted-U relationship. Unfortunately we are not. We are replacing biodiversity rich natural forest cover with sterile pine plantations. Good news for carbon capture (maybe) but bad new for species diversity.

No doubt this study enriches our knowledge of global forest stocks and is very worthy in that sense. But the scope for optimism seems rather overstated and risks sending the wrong message to those countries looking for an excuse to relax the protection of their forests.



Anonymous said...

Even the sterile pine plantations are not helpful in mitigating global warming. Younger trees store more carbon, and pine plantations are meant for rotation every 20-30 years in the Southern U.S., releasing more CO2 into the atmoshere. The problem starts with the original logging of native forests in the south, and is compunded by the logging of pine plantations at an unprecedented rate. The southern U.S. has almost 32 million acres of pine plantations that have been converted from natural forests which play a major role in mitigating global warming.

Matt Cole said...

You're quite right of course. Thanks for the comment. It's hard then to see any scope for optimism in the study's findings. Although I suppose we should be grateful that the natural forest isn't being replaced agriculture or industry. Things could be worse.

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