The Intricate Link Between Plant Biodiversity and Soil Carbon Storage in Grasslands

Grasslands, which hold a third of the world's terrestrial carbon, are at the forefront of a groundbreaking study led by Marie Spohn from the Swedish University of Agricultural Sciences. This research, encompassing 84 grasslands across six continents, reveals a direct correlation between plant biodiversity and soil carbon storage. Surprisingly, the increase in soil carbon wasn't due to more plant biomass in species-rich grasslands. Instead, the key lies in the chemical makeup of the vegetation. Grasslands with diverse plant species had a higher carbon-to-nitrogen ratio, meaning their plant biomass contained less nitrogen relative to carbon. This translates to plants having fewer proteins compared to fibers, which decompose slower in the soil. As a result, more carbon remains stored. Notably, this trend intensifies in warm and arid climates, possibly because plants in these regions produce complex compounds that decompose slowly, serving as a shield against harsh conditions. Contrary to prior beliefs, this study underscores that soil carbon storage isn't just about the quantity but also the quality of organic matter.