During the climate change discussions, some have argued that, given that old-growth forests are carbon reservoirs --and not carbon sinks-- the world's climate would benefit from cutting them down, converting the wood into durable products and replanting the clearcut area. The existing carbon would be safely stored in wood products and the plantation trees would act as sinks for many years, until they reached maturity. This would enhance --so they say-- the carbon sink capacity of forest ecosystems.
Apart from the many flaws of such approach, a recent study has shown the importance of old-growth forests as carbon sinks and has warned against their substitution by plantations. The research concludes that forests are far better than plantations at ridding the air of carbon dioxide. The analysis, published in the journal Science, was carried out by Dr. Ernst-Detlef Schulze, the director of the Max Planck Institute for Biogeochemistry in Jena, Germany, and two other scientists at the institute.
The German study, together with other similar research, has produced a picture of mature forests that differs sharply from long-held notions in forestry. Dr. Schulze says that aging forests were long perceived to be in a state of decay that releases as much carbon dioxide as it captures. But it turns out that the soils in undisturbed tropical rain forests, Siberian woods and some German national parks contain enormous amounts of carbon derived from fallen leaves, twigs and buried roots that can bind to soil particles and remain there for 1,000 years or more. When such forests are cut, the trees' roots decay and soil is disrupted, releasing the carbon dioxide. Centuries would have to pass until newly planted trees built up such a reservoir underground.
The study's authors stress the need to protect old-growth forests. Without such protection, the scientists conclude, some countries could be tempted to cut down old-growth forests now and then plant new trees on the deforested land, getting credit for reducing carbon dioxide when they have actually made matters worse.
Several climate and forestry experts familiar with the work have said the study provided an important new argument for protecting primary forests. They add that the study also provides a reminder that the main goal should be to reduce carbon dioxide emissions at the source.
Article based on information from "Planting New Forests Can't Match Saving Old Ones in Cutting Greenhouse Gases, Study Finds", by Andrew C. Revkin, New York Times September 22, 2000