Mycorrhizal distributions impact global patterns of carbon and nutrient cycling

Most tree species predominantly associate with a single type of mycorrhizal fungi. Because of the principle differences in mycorrhizal associations, they can differentially affect plant nutrient acquisition and biogeochemical cycling. Here, we use the updated carbon-nitrogen economics within the Community Land Model version 5 (CLM5) to evaluate the impact of mycorrhizal association on the global nitrogen and carbon cycles. Different spatial distributions of plant mycorrhizal associations lead to clear differences in present day Net Primary Productivity by up to 345  21 TgCyr-1, owing to the impacts of different symbioses on carbon costs of nitrogen acquisition (4.3% more costly than those originally proposed on average). Simulated global NPP increased throughout the 21st century by 20%, while the carbon costs of nitrogen acquisition have increased at a faster rate by 50%. This suggests that nutrient acquisition will increasingly demand a higher portion of assimilated carbon to support the same productivity.