*For correspondence:
Email: andrew.kulmatiski@usu.edu
Abstract
- Plant-soil feedback (PSF) has gained attention as a mechanism
promoting plant growth and coexistence. However, most PSF research has
measured monoculture growth in greenhouse conditions. Translating PSFs
into effects on plant growth in field communities remains an important
frontier for PSF research.
- Using a four-year, factorial field experiment in Jena, Germany, we
measured the growth of nine grassland species on soils conditioned by
each of the target species (i.e., PSF). Plant community models were
parameterized with or without these PSF effects, and model predictions
were compared to plant biomass production in new and existing
diversity-productivity experiments.
- Plants created soils that changed subsequent plant biomass by 36%.
However, because they were both positive and negative, the net PSF
effect was 14% less growth on ‘home’ than ‘away’ soils (i.e., the
average PSF value was -0.14). At the species level, seven of nine
species realized non-neutral PSFs. At the species*soil type level, 31
of 72 PSFs differed from zero. The two dominant species grew only 2%
less on home than away soils.
- In current and pre-existing diversity-productivity experiments,
nine-species plant communities produced 37 to 29% more biomass than
monocultures due primarily to selection effects. Null and PSF models
predicted 29 to 28% more biomass for polycultures than monocultures,
again due primarily to selection effects.
- Synthesis: In field conditions, PSFs were consistent and large
enough to be expected to affect plant growth and coexistence. However,
overyielding in plant communities was caused by selection effects so
complementarity effects caused by PSF were not important in these
communities. We identified several reasons that even large PSFs may
not affect plant productivity. In general, we found that both large
positive and large negative PSFs were associated with subdominant
species. Because of this, we suggest there may be selective pressure
for plants to create neutral PSF. Broadly, testing PSFs in plant
communities in field conditions, highlighted new directions for
understanding PSF effects in communities in the context of other
species traits.
Keywords: aboveground-belowground interactions,
biodiversity-ecosystem functioning, dominance, plant community model,
plant identity, biomass