Fossil evidence shows that early land plants hosted fungal symbionts, which are likely to have facilitated phosphorus acquisition by plants and thus increased net primary production, perpetuating the transition to a cooler, oxygen-rich environment suitable for animal life. Mills’ study tests this hypothesis by integrating plant-fungal phosphorus acquisition into a biogeochemical model of the Paleozoic climate transition. The study finds “significant Earth system sensitivity to phosphorus uptake from mycorrhizal fungi” [Mills 2017: 7], and that “efficient phosphorus uptake at superambient CO2 results in enhanced carbon sequestration, which contributes to a reduction in CO2 and drives a rise in O2” [Mills 2017: 6].
Understanding drivers of an historic climate cooling is obviously relevant today given current atmospheric CO2 accumulation. This study points to the importance of plant-fungal symbioses and phosphorus cycling, and thus to the importance of building and protecting soil health to allow such symbioses to flourish.
Mills, Benjamin J.W., Sarah A. Batterman and Katie J. Field, 2017, Nutrient acquisition by symbiotic fungi governs Paleozoic climate transition, Philosophical Transactions Royal Society B 373: 20160503, http://rstb.royalsocietypublishing.org/content/373/1739/20160503.