Does Protecting Old Forests Help Reduce CO2?
Posted by Max Dunn Thu, 23 Oct 2008 14:31:00 GMT
In a previous post, I discussed some of the problems with carbon credits. Here is another example of a project that doesn’t seem like it is really reducing CO2.
The Garcia River Forest project is a certified carbon offset project that PG&E is sponsoring and protects trees that would otherwise be harvested. This seems like a good thing – leaving forests standing rather than cutting them down seems like it would reduce CO2. Right?
However, there is a problem. A growing forest sequesters a lot more carbon than a mature one. Of course, if the forest was cleared by burning, that would be bad because it would release a lot of CO2. But, if the forest was responsibly and sustainably harvested to make lumber, the CO2 would effectively be sequestered and then the young forest would soak up additional CO2.
So for maximum CO2 sequestration, it would actually be better to harvest as many forests as possible for lumber and re-plant them! Of course forests offer a lot of other benefits besides just CO2 sequestration, so we would never want to cut them all down. But the point is, if we really want to make a dent in CO2, we have to look carefully at all the effects of our efforts and not just make quick assumptions.
I enthusiastically agree with the need to avoid simplistic conclusions. And it is interesting to consider the idea that growing forests may use more CO2 than mature ones. But I would argue that when a forest is harvested, the CO2 sequestration rate drops precipitously for several years until a sufficient biomass of new trees emerge. Having recently traveled extensively thru vast areas of “managed” forest, I can tell you clearcutting appears to be the norm. Even when they leave a stand of trees along the road, or rotate sectors by clearcutting one at a time, it is still reducing the carbon sequestration dramatically for that plot of land.
Also, I’d be curious what fraction of the wood that is harvested becomes useful building materials vs. the sawdust and scraps that become “fuel” (thus defeating the purpose of sequestering carbon).