What is the importance of forest logging operations for climate and climate change?

What is the importance of forest logging operations for climate and climate change?

Forests influence climate by affecting largely the amount of carbon dioxide in the atmosphere. Forests absorb carbon dioxide through photosynthesis and release it through respiration. When a forest ecosystem is acting as a carbon sink, it sequestrates more carbon that is released in respiration, and the carbon stock of the ecosystem increases. In the past few decades, the forests have absorbed globally around 30% of carbon dioxide emissions from the use of fossil fuels (Pan et al. 2011, Le Quéré et al. 2018).

Climate benefits of carbon sequestration in a forest ecosystem remain until the saturation of the sink, at which time the ecosystem carbon stock is at highest. Forest logging operations decrease the carbon stock of an ecosystem temporarily through harvest of biomass (timber, energy biomass). The postharvest recovery of carbon stock through forest growth depends e.g. on climate, site type, tree species, harvest intensity. Partial cuttings (i.e. thinnings) affect the postharvest recovery of ecosystem carbon stocks less and shorter time period than the clear cuttings.

After logging, harvested wood products (e.g. sawn wood, panels, pulp and paper products) reduce atmospheric carbon dioxide by storing carbon outside the forests until the inflow to the products´ pool is higher than the outflow from the pool. In addition, harvested wood products can produce climate benefits by replacing fossil-fuel-intensive products and fossil fuels (e.g. concrete, plastic, coal) and hence avoid additional atmospheric carbon from the use of fossil-fuel-intensive products and fossil fuels. The carbon in harvested wood products, unlike in many alternative products, can also be used for energy at the end-of-life stage.

Therefore, total climate impacts of forests depend on the effects of logging operations on ecosystem carbon sinks, but also the potential of harvested wood products to store carbon outside forests and to avoid emissions from using alternative fossil-fuel-intensive materials and fossil fuels. In addition, calculated climate impacts of forests are highly dependent on system boundaries of the analyses and selected reference situations (e.g. baseline management and harvest intensity of forests) against which the climate impacts of forests are evaluated.

Pan et al. (2011) A Large and Persistent Carbon Sink in the World’s Forests. Science 333, 988.

Le Quéré et al. (2018) Global Carbon Budget 2017. Earth System Science Data 10:405–448.