A group of researchers, led by Jesús Aguirre-Gutiérrez from the University of Oxford, has found that the actualimpact of planting trees is quite disappointing: biodiversity declines while carbon storage remains limited.
Planting trees to offset CO2 emissions has become a trend, particularly in the tropics where large monoculturetree plantations are established because trees grow faster there, sequestering carbon more quickly. The concept seems logical: trees remove carbon from the atmosphere, so if we plant enough of them, we can naturallymitigate climate change.
However, carbon sequestration tree plantations are usually monocultures dominated globally by just five tree species: teak, mahogany, cedar, silk oak, and acacia. Economically, this makes sense, but biodiversity in thoseforests is often lacking. Sometimes, infertile old forest soil is used, but more often, trees are planted in areas thatwere never forests but healthy biodiverse grasslands.
Moreover, an even more critical point made by the researchers is that even with significant efforts, the carbon storage capacity of such tree plantations is limited. “The current trend of planting trees for carbon storage leads to extensive homogenization for a small carbon gain,” state the researchers. “An area as large as the US, the UK, China, and Russia combined would need to be forested to sequester one year’s worth of emissions.” This is completely unfeasible. “In conclusion, prioritizing the preservation of the original ecosystem and maximizing itsfunctions should take precedence over the economic focus on carbon storage projects,” they emphasize.
Valuing the functionality of tropical ecosystems beyond carbon: Trends in Ecology & Evolution (cell.com)