Despite their total area having increased by 10% since 1750, European forests have failed to achieve a net removal of CO2 from the atmosphere because of how they’ve been managed over that time. Eighty-five percent of Europe’s once largely unmanaged forest has been subjected to tree species conversion, wood extraction via thinning and harvesting, and litter raking, resulting in a large overall loss of carbon from biomass and soil.
Putting 417,000 km2 of previously unmanaged forest into production is estimated to have released 3.5 Pg of carbon to the atmosphere, because the carbon stock in living biomass, coarse woody debris, litter, and soil was simulated to be, respectively, 24, 43, 8, and 6% lower in managed forests compared with unmanaged forests [Naudts 2016: 598].
The sweeping change in Europe’s forest species from broad leaf trees to conifers represents a shift to a production-oriented approach to forestry undertaken to satisfy demands of a population that quadrupled between 1750 and 2010.
Whereas deforestation between 1750 and 1850 mainly replaced broadleaved forests with agricultural land, afforestation from 1850 onward was often with coniferous species. Broadleaved forests were also directly converted to coniferous forests, resulting in a total increase of 633,000 km2 in conifers at the expense of broadleaved forests (decreasing by 436,000 km2). For centuries, foresters have favored a handful of commercially successful tree species (Scots pine, Norway spruce, and beech) and, in doing so, are largely responsible for the current distribution of conifers and broadleaved species in Europe [Naudts 2016: 598].
The authors note that many other parts of the world have followed a similar path,
Wood extraction occurs in 64 to 72% of the 26.5 to 29.4 million km2 of global forest area, and substantial species changes have occurred in China (216,000 km2), Brazil (71,000 km2), Chile (24,000 km2), New Zealand (18,000 km2), and South Africa (17,000 km2) [Naudts 2016: 599].
This global trend has resulted in limiting the ability of many managed forests to sequester carbon, compared to their wild or better-managed counterparts.
Hence, any climate framework that includes land management as a pathway for climate mitigation should not only account for land-cover changes but also should equally address changes in forest management, because not all forest management contributes to climate change mitigation [Naudts 2016: 599].
Naudts, Kim, et al., 2016, Europe’s forest management did not mitigate climate warming, Science 351, https://science.sciencemag.org/content/351/6273/597.