Data from: Mycorrhizal identity and light shape tree seedling biomass responses in plant–soil feedbacks

Plant–soil feedbacks (PSFs) are key drivers of forest composition and
diversity, yet their direction and magnitude may depend on the mycorrhizal
identity of interacting species, environmental conditions, and
experimental context. We conducted complementary greenhouse and field
experiments using Acer rubrum L., Acer saccharum Marsh., Prunus serotina
Ehrh. (all arbuscular mycorrhizal [AM] species), and Quercus alba L., and
Quercus rubra L. (all ectomycorrhizal [EM] species) to test how
biomass-based PSFs vary with mycorrhizal matching between seedlings and
adult trees, light availability, and soil microbial communities. Seedlings
were grown in soil conditioned by conspecifics, conmycorrhizal
heterospecifics, or heteromycorrhizal heterospecifics under controlled and
natural light regimes. Consistent with expectations, AM species
consistently exhibited negative PSFs under low light, and EM species
tended to show more positive PSFs, but this pattern was contingent on
light and greenhouse versus field setting. For AM species, negative PSFs
occurred primarily under low light and were neutralized or reversed under
higher light. EM species showed generally more positive PSFs across light
levels and settings, although species-specific differences emerged. PSFs
were driven largely by conspecific soil conditioning, with limited
influence from the mycorrhizal identity of heterospecific neighbors.
Results from greenhouse versus field settings diverged, with field PSFs
sometimes attenuated or reversed, particularly for Q. alba. These findings
highlight that biomass-based PSFs are not fixed species traits but
context-dependent outcomes influenced by mycorrhizal type, light
availability, and environmental setting. Incorporating these factors is
essential for predicting how PSFs influence seedling recruitment, forest
dynamics, and biodiversity.