Trees sequester large amounts of carbon from the atmosphere. Keeping that fact in mind, researchers at Wageningen UR approach the restoration of tropical forests from various sides and on several continents. The final effect of the projects will depend on the degree to which the rich countries want to invest in that storage function.
Forty to one hundred years, that is how long it takes a parcel of forest robbed of all its wood has regained the complete carbon configuration of the original natural forest. “Some people consider that a very long time, but I don’t think it’s that bad at all,” says Frans Bongers, full professor of tropical forest ecology at Wageningen University. Bongers investigates the recovery process of tropical forests. “Since the large-scale deforestation in the 1990s, 350,000 square kilometers of new forest have developed worldwide of which we know that it’s still standing.” he tells us.
As trees fix carbon - one of the two elements that make up carbon dioxide (CO2) - the expansion of forest area pushes back the amount of carbon dioxide in the atmosphere considerably. After all, the fixed carbon is no longer available for the formation of CO2. “It is therefore important that we not only leave the forests alone and protect them, but also restore them.” says Bongers.
The recovery period of minimally forty years is quite manageable, he feels. Moreover, planting extra trees can speed up the process and the effect. “Calculations show that a quarter of the earth’s land surface currently consists of abandoned badlands where not much is happening. On some of those, we could plant forests of species that sequester a lot of carbon.”
Bog woodlands
Notably major carbon gains can be made in the restoration of tropical bog woodlands, in which not only the trees but also the bog grounds contribute to CO2 fixation. These woodlands cover only a quarter percent of the earth’s land surface, but with their bogs hold as much as three percent of all the carbon stored in the world’s forests and soils. “In recent years, we’ve become increasingly aware of the importance of these wet bog woods eco systems.” says Henk Wösten, researcher at Alterra.
For the World Wildlife Fund, he and others are working toward the recovery of wet bog woods in Indonesia. “Farmers would rather convert the economically often not lucrative bog woods into productive agricultural land.” he elaborates. Large-scale logging and the construction of drainage channels cause the bog to dry out which allows air to penetrate the soil. The carbon in the bog reacts with the oxygen molecules and is subsequently released as carbon dioxide. That changes the bog from a sink to a source of carbon dioxide.
Wösten, as expert in the area of soil and hydrology, is deployed to restore the bog woods to their old waterlogged state. “To be able to return to the original situation, the drainage channels have to be closed.” he explains. “It sounds simple, but it concerns millions of hectares of bog grounds that are not adjoining.” With the aid of models that combine soil science and hydrology, Wösten analyses the locations of the channels and determines the best sites for building dams to resaturate the area with water.
Recovery of the bog woods will take longer than the forty to one hundred years calculated for tropical forests because it takes them a lot of time to grow. “The peat layer under a bog wood grows by about 1 mm per year,” says Wösten. It will therefore take five hundred years to form half a meter of peat previously lost.
Support
The result of the recovery projects strongly depends on the support of the local population. “We can’t just tell people to leave the peat alone.” Wösten says. Certainly not when a large part of the bog wood is cut in order to meet the rich western countries’ large demand for palm oil.
It is up to the rich countries to provide financial compensation to enable recovery and preservation of the bog forests as carbon reservoirs, feels Wösten. “If the global community wants to preserve the bog areas, the Netherlands and other western countries have to commit and pay for that carbon storage.”
On top of that, it’s attractive to invest in sustainable management of forests. “We are currently trying to push back the emission of CO2 with measures such as double glazing and cleaner cars, but the yield is relatively small per invested euro.” Smaller than that of preserving tropical bog woods as carbon sinks.
According to Wösten, the peat has now become valuable because of its ability to store carbon. “Just like Cinderella, the previously neglected peat has suddenly turned into a beautiful and widely desired princess. Farmers in Indonesia currently get their income from growing oil palms. In the future, they may be able to support themselves just as easily by managing the carbon stored in those bog woods.”
Source: Wageningen update 3/09, Laurien Holtjer