куќарка истражувања Managed forests and renewable wood reduce greenhouse gases
Managed forests and renewable wood reduce greenhouse gases Print E-mail
Written by sekira   
петок, 04 април 2008 09:20

Forests, and the wood-products they produce, can absorb or produce highly variable amounts of CO2, depending on how they are managed. New research provides guidelines for harvesting forests, while limiting greenhouse gas emissions. Wood is a renewable resource and the greatest environmental benefits from using wood occur when it is used first in the construction industry, and then recycled, if practical, or used to generate energy.

Swiss research explored the ways the forestry and timber sector could contribute to a reduction in greenhouse gases (GHG), for example, when forests act as a carbon sink by absorbing CO2, when carbon is sequestered in the form of wood products and through the substitution of wood for fossil fuels. Possible forest management techniques and scenarios for using wood were modelled and the part these techniques could play in reducing GHG emissions or on CO2 absorption was simulated to develop a range of options for future policy. Scenarios included:

  • the impact on carbon sequestration of different levels of intensity of forest management from 1996 to 2096
  • the effects of storing wood and foreign trade in wood products from 1900 to 2150
  • the comparison of life-cycles of wood products and their non-wood substitutes, taking into account the effects of foreign trade

Results showed that maximising the harvesting of wood as a renewable resource produced the most sustainable improvement on the CO2 balance. In Switzerland, the researchers estimated that around 9.2 million m3 of forest could be used for renewable wood supplies. Increases in wood use, especially in the construction sector, led to better improvements in CO2 balance than using wood directly for energy. If wood is used first as a material and then recycled for energy use, the savings in terms of CO2 emissions could be doubled.

Reducing forest maintenance in the short to medium term would generate an initial forest sink effect, but under current Kyoto provisions, there is a limit to the amount of CO2 absorbed by forests that can be used to off set CO2 emissions. Additionally, the model suggests that there could be a net increase in emissions of CO2 from forests towards the end of this century - an effect that could occur even sooner if a lack of management resulted in forest collapse due to age. Lack of forest management would also lead to greater use of non-wood resources in construction and for energy (or an increase in wood imports), reducing the carbon sink effect still further.

When the impact of foreign trade is taken into account, increasing use of wood in construction also produces the best balance in the medium to long term. The researchers recommend:

  • forests should be managed to yield wood at the maximum sustainable levels
  • wood harvesting should be used to manage this increase
  • the harvested wood should be processed in accordance with the principle of cascade use (first in long-living wood-products, such as in construction and then for energy)
  • waste wood that is not suitable for further use should be used to generate energy

The simulation models used in this report are also relevant to the management of forests throughout Europe and for the management of trees planted as part of carbon off setting schemes.

Source: Swiss Federal Office for the Environment (2007). The CO2 effects of the Swiss forestry and timber industry. Scenarios of future potential for climate-change mitigation. Download from: http://www.bafu.admin.ch/php/modules/shop/files/pdf/phpKVKm5f.pdf

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