Data and code for "Vertical root distribution underpins belowground resistance to extreme drought"

Extreme droughts are becoming more frequent and strongly affect ecosystem primary productivity. However, the effects of drought on belowground productivity—key to the carbon cycle—remain underexplored and may vary with precipitation levels and soil depth. Using a coordinated drought experiment across six grassland sites spanning a precipitation gradient in Eurasia, we found that extreme drought did not affect root biomass or belowground net primary productivity (BNPP) across the 0-20 cm soil profile. However, drought induced a depth-specific shift: in xeric grasslands, root biomass and BNPP increased in the 0-10 cm layer but declined in the 10-20 cm layer, whereas mesic grasslands exhibited the opposite pattern. These contrasting responses were largely regulated by changes in soil moisture with depth. Consequently, the overall resistance of belowground productivity to extreme drought reflects a vertical redistribution of root growth. Incorporating such depth-dependent root responses into carbon cycle models is essential for improving predictions of ecosystem carbon dynamics under intensifying climate extremes.