Data from: Plant economic strategies of grassland species control soil carbon dynamics through rhizodeposition

1. The plant economics spectrum is increasingly recognized as a major
determinant of plant species effects on terrestrial ecosystem functioning
related to carbon cycling. However, the role of plant economic strategies
in the effects of living root activity on soil organic carbon (SOC)
dynamics through rhizodeposition remains unexplored, despite SOC being the
largest terrestrial carbon pool. 2. Using a continuous 13C-labeling method
allowing partitioning of plant and soil sources to carbon fluxes and
pools, we studied here the linkages between plant economic strategies and
SOC cycling processes in a ‘common garden’ greenhouse experiment. It
includes a panel of 12 grassland species selected along a gradient of
economic traits and belonging to three functionnal groups (C3 grasses,
forbs and legumes). 3. All species induced an acceleration of native SOC
mineralization but this rhizosphere priming effect (RPE) substantially
differed across species and varied eleven-fold by the end of the
experiment (from +26 to +295 % relative to unplanted soil). Interspecific
variation in RPE was primarily linked to plant photosynthetic activity
associated to species economic strategies of light and CO2 resource
acquisition and processing. Fast-growing acquisitive species, such as
legumes, featured large RPE, in relation with their high canopy
photosynthesis coupled to high leaf photosynthetic capacity and large net
primary productivity allocated aboveground. This large RPE was further
associated with high root metabolic activity, rhizodeposition and soil
microbial activity. In contrast, fine-root growth and economic traits
related to soil resource foraging ability were poor predictors of RPE. 4.
The formation of new root-derived SOC varied nine-fold across species and
was similarly positively related to the net primary productivity allocated
aboveground. Fast-growing acquisitive species with a high photosynthetic
activity induced a disproportionately large RPE relative to SOC formation.
5. Synthesis. Overall, our study demonstrates that rhizodeposition is a
major mechanism through which plant economic strategies of grassland
species control soil carbon dynamics. Acquisitive versus conservative
species were associated with high versus low rates of photosynthesis and
rhizodeposition, in turn leading to fast versus slow SOC turnover. This
emphasizes the importance of considering rhizosphere processes for
understanding plant species effects on soil biogeochemistry.