Does Cutting a Tree Create Greenhouse Gas?
by Lloyd Alter, Toronto on 03.14.07
I am confused. Vancouver's ForestEthics is protesting the logging of Ontario's boreal forest. They say "Industrial logging of (Ontario's) forests is a significant contributor of carbon dioxide." and "On average, about 210,000 hectares of forest are logged in Ontario each year. Cutting those trees releases the equivalent of 15 million tonnes of carbon dioxide, or about 7 per cent of the province's total of 203 million tonnes."
This treehugger always promotes wood as the best building material to fight global warming, because the carbon is sequestered for the life of the building. When we talked about FMO Tapiola, the Finns said "Wood serves as a carbon sink by absorbing and binding carbon dioxide. One cubic meter of wood stores nearly one ton of carbon dioxide. The storage process of carbon dioxide continues inside the wood products through their entire life cycle." and "The substitution effect of wood products has a significant impact on construction industry’s carbon dioxide emissions. The use of wood products replaces building materials that would have required a great deal of fossil energy to produce."
Evidently the Kyoto Protocol stipulates that emissions are to be counted as soon as trees are cut; we understand that to be because most deforestation leads to burning of the wood. While we do not support the clear-cutting of the Boreal forests, what about a sustainably managed, efficient forest? Next to recycled wood, is that not the best material around? If a tree is felled in the woods for lumber or building materials, why does it count as carbon? ::The Star
Sustainably managed forests wouldn't be a problem. The problem here (I'm assuming) is that they are using gasoline driven chainsaws to cut old-growth forests, then hauling the logs out with fossil-fuel powered trucks. Thus, overall emissions from cutting down an acre of forest is much higher than just the carbon in the trees themselves.
There was recently a gathering of scientists in Oregon to discuss the role forests and forestry play in sequestring atmospheric carbon. Dean Hal Salwasser of the Oregon State University College of Forestry has a great presentation exploring the significant role of carbon sequestration that wood products play, and how loss of forestland to development and agriculture is diminishing that carbon storage potential. You can view his presentation, as well as the other scientists who presented at http://www.oregonforests.org/conferences/carbon
In Canada, wood can certainly make sense (especially in a sustainably harvested forest). In other places, wood makes less sense because there is so little of it and it is more beneficial as an ecosystem than as a building material.
As usual, local conditions must be kept in mind.
In the case of BC, could it be that the protesters just did the inverse math on how much carbon dioxide is sequestered by trees? There are a bunch of online calculators. Maybe they just inversed the math.
What's important is the reforestation standard. Trees that are cut have to be replanted quickly, and forestry and erosion officials can assure this happens. A small woody plant absorbs C02 at a faster rate than a mature tree, so the process has some compensation built in.
Another opportunity is coppice, practiced in New England a lot during the colonies. When trees smaller than 8" were cut, the trunks would re-sprout growth next season, and a single root system would effectively raise two or three generations of tree trunks.