August 2009
The conference of United Nations in Copenhagen, which has to be held from 7 till 18 December, joins as decisive moment for the future of the humanity. According to the Intergovernmental Pannel on Climate Change (IPCC), it became imperative to reduce the world level of issues of CO2, 60% with regard to what it was in 1990 and it, before 2050 (80% in the rich countries and 20% somewhere else).
Such an objective seems for the moment it can't be reached. The United States intend to reduce their issues of no more than 4% and Japan limits itself to an objective of 8% reduction. Emerging countries such as China and India refuse to sign any commitment of reduction of their issues, as long as industrial nations will not have subscribed to an objective of 40% reduction with regard to 1990, by 2020, such as prescribed by IPCC. It's the same for Brazil and Afrique-du-Sud. Besides, most of the managers of this world get to say that the solution of the current crisis passes by a reconfiguration of the traditional economy in a green economy. It is not only necessary to change our current principles but much more still, to modify our ways of life, our consumer regime. The economy effectively has to collaborate to resolve the threat of the global warming.
We have to reduce the anthropological sources of CO2 but also, increase the sources by it of illegal securement and the stocking. Forests establish real wells of carbon while they contain about 30% of all the ground carbon. Thanks to the photosynthesis, the forested ecosystems absorb the carbon contained in the atmosphere and store it in the vegetable biomass.
The net primary production (NPP) is the parameter held to establish the net rate of absorption of the carbon by plants. It corresponds to the difference between the rates of photosynthesis and breath. The NPP of the forested ecosystems varies according to several factors among which the composition and the age of the populatings. In maturity, a forest stops storing some carbon. Certain natural events such as the cycle of fires in boreal forest for example, allow to restart the process. However, the carbon until then stored in trees, returns directly or indirectly to the atmosphere. Within the framework of a follow-up of the variation of the NPP in the time, we observed a decrease going from 30% to 80% of the Canadian boreal NPP of forests and Alaska, from the first year following a fire. The necessary period so that a burned forest reaches its level of productivity of front fire varies a lot ; from 2 to 50 years. Following a fire, forests behave as net sources of carbon issued in the atmosphere and become again net wells after period varying from 1 to 24 years.
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The boreal forest as well of carbon
The Montmorency forest gets annually, 10 tons of carbon per hectare. It contains at present 173 tons of carbon per hectare on average which divide up as follows:
- 45 tons in the wood
- 15 tons in branches and leaves
- 13 tons in roots
- 30 tons in the humus
- 70 tons in the mineral ground
The distribution of the carbon put in reserve in the forest Montmorency
The forested ecosystems thus play a role essential as well of carbon, but also all the wood of work produced by the forest industry. The wood of work constitutes effectively a durable reserve of carbon while it keeps this last one held during all the useful life of buildings and furniture for which they serve as materials. Compared with other materials used in the construction wood of which the concrete and the steel, the material also requires much less energy to extract and transform it ; what makes a green material in several consideration.
