Vegetation and carbon

This paper is not peer reviewed but covers an important summary about relative pros/cons of BECCS and the alternatives of silvopasture and evergreen energy (perennial agriculture).
Freeing land for natural ecological succession is a worthwhile low‐cost natural climate solution that has many co‐benefits for biodiversity and other ecosystem services. Allowing agricultural land to follow a natural succession (any kind of regrowth of natural vegetation) pathway must seriously be considered as an alternative climate change mitigation strategy to bioenergy.
Intact forests store much more carbon than logged, degraded or planted forests.
Big old trees fix more carbon than smaller trees (contrary to previous orthodoxy)
Ectomycorrhizal (EM) fungi is fundamental to understanding the complex functioning of forests and carbon sequestration potential. EM enable trees:
  • to accelerate photosynthesis in response to increased concentrations of atmospheric CO2 when soil nitrogen is limiting (a)
  • to inhibit soil respiration by decomposer microorganisms (a)
  • to allow saplings to develop under the canopy of parent trees (b)
EM is destroyed when forests are logged / ECM fungal diversity and relative abundance is preserved in proportion to the amount of retained trees. (c)
Conversion from natural vegetation to cropland changes the composition of fungi types away from ectomycorrhizal vegetation, which is associated with significantly higher soil carbon sequestration rates.
Arbuscular, ectomycorrhizal, and ericoid mycorrhizal vegetation store, respectively, 241 ± 15, 100 ± 17, and 7 ± 1.8 GT carbon in aboveground biomass, whereas non-mycorrhizal vegetation stores 29 ± 5.5 GT carbon. Soil carbon stocks in both topsoil and subsoil are positively related to the community-level biomass fraction of ectomycorrhizal plants, though the strength of this relationship varies across biomes. We show that human-induced transformations of Earth’s ecosystems have reduced ectomycorrhizal vegetation, with potential ramifications to terrestrial carbon stocks. Our work provides a benchmark for spatially explicit and globally quantitative assessments of mycorrhizal impacts on ecosystem functioning and biogeochemical cycling.