Extended Data Fig. 1: Global comparison of the phosphorus status at EucFACE.

(a) Density distribution of global gridded plant-available soil phosphorus (P) concentration for the top 9.1 cm of the soil (mg P kg⁻¹), estimated based on the Bray I method⁵⁶. The black line indicates gridded plant-available soil P concentration for the EucFACE location (9.34 mg P kg⁻¹ soil, equivalent to the ~40^th percentile). (b) Global measurements of plant-available soil P concentration (mg P kg⁻¹), extracted based on the Bray I method⁵⁷, grouped into different forest biomes. (c) Density plot for the paired leaf nitrogen (N) and P concentration for trees, as in ref. ²¹ but using data from ref. ⁵⁸. Black dots indicate individual data points; red dot indicates leaf nutrient measurement at EucFACE. Orange solid and purple dotted lines indicate leaf P:N ratio of 1:16 and 1:20, respectively; see refs. ^3,21. (d) Comparison of the size of the plant phosphorus (P) pool (g P m⁻²) at EucFACE to a those compiled for temperate and subtropical forest biome based on a regional dataset (n = 1969)⁵⁹. (e) Same as d, but for the ratio between plant P to total soil P pool (0 − 60 cm). (f) Comparison of soil microbial phosphorus (P) at EucFACE to a global dataset³¹, expressed as the fraction of soil organic P as microbes (i.e., microbial P over total soil organic P over the top 60 cm of soils). The bounds of the whisker box indicate the upper quartile and lower quartile of the data, respectively, and the line within the box indicates the median. The black line indicates average value based on ambient CO₂ plots at EucFACE (n = 3).