Data from: Plant traits and tissue stoichiometry explain nutrient transfer in common arbuscular mycorrhizal networks of temperate grasslands

Plants and mycorrhizal fungi form mutualistic relationships that affect
how resources flow between organisms and within ecosystems. Common
mycorrhizal networks (CMNs) could facilitate preferential transfer of
carbon and limiting nutrients but this remains difficult to predict. Do
CMNs favor fungal growth at the expense of plant resource demands (a
fungi-centric view), or are they passive channels through which plants
regulate resource fluxes (a plant-centric view)? We used stable isotope
tracers (13CO2 and 15NH3), plant traits, and mycorrhizal DNA to quantify
above- and belowground carbon and nitrogen transfer between 18 plant
species along a 520-km latitudinal gradient in the Pacific Northwest, USA.
Plant functional type and tissue stoichiometry were the most important
predictors of interspecific resource transfer. Of “donor” plants, 98% were
13C enriched, but we detected transfer in only 2% of “receiver” plants.
However, all donors were 15N enriched and we detected transfer in 81% of
receivers. Nitrogen was preferentially transferred to annuals (0.26 ± 0.50
mg N per g leaf mass) compared to perennials (0.13 ± 0.30 mg N per g leaf
mass). This corresponded with tissue stoichiometry differences. Our
findings point to a simple mechanistic answer for long-standing questions
regarding transfer of resources between plants via mycorrhizal networks.