The carbon sequestration potential of terrestrial ecosystems

Excerpt

Terrestrial ecosystems, comprising vegetation and soil in uplands and wetlands, significantly impact the global carbon (C) cycle and, under natural conditions, are a sink of atmospheric carbon dioxide (CO₂) and methane (CH₄). However, conversion of natural to managed ecosystems (i.e., agroecosystems, urban lands, and mined lands) depletes ecosystem C stocks, aggravates gaseous emissions, and exacerbates radiative forcing. Thus, the onset of agriculture around 8000 BC presumably transformed these sinks into a source of greenhouse gases (GHGs) (Ruddiman 2003), mostly CO₂, CH₄, and nitrous oxide (N₂O), and depleted the terrestrial (soil, vegetation, and peatlands) C stocks. Ruddiman (2005) estimated the depletion of the terrestrial C stock (soil and vegetation) by 456 Pg (502.65 × 10⁹ tn) since the onset of agriculture. Of this, the historic depletion of soil organic carbon (SOC) stock is estimated at 130 to 135 Pg (143.3 × 10⁹ to 148.8 × 10⁹ tn) (Sanderman et al. 2017; Lal 2018). Therefore, recarbonization of some of the terrestrial biosphere (soil and vegetation) is an important strategy to mitigate the anthropogenic climate change (ACC) and enhance other ecosystem services because of the link between SOC stock and atmospheric concentration of CO₂ (Trenberth and Smith 2005).

Recarbonizing the terrestrial biosphere involves…