DOI: 10.5061/dryad.gk15h50
title: Data from: The balance of canopy and soil effects determines intraspecific differences in foundation species’ effects on associated plants

description: 1. The impact of plant-plant interactions on species diversity patterns
 has been broadly addressed in stressful environments, such as alpine
 ecosystems, where foundation species promote species richness by creating
 habitat for other species. However, foundation species with contrasting
 phenotypes might modify the microhabitat differently, which would alter
 the subordinate community composition, and coincide with distinct feedback
 effects of those subordinate species on the foundation species. However,
 the precise interaction mechanisms that facilitate species are not fully
 understood, especially the relative contribution of above- and
 below-ground compartments of foundation species to subordinate species and
 the potential feedbacks they receive. 2. We explored whether two
 contrasted canopy phenotypes (tight and loose) of the shrub Cytisus
 galianoi differed in their effects on the microhabitat and on subordinate
 plant community composition in a dry subalpine system. We also
 experimentally distinguished the relative contribution of above- (canopy)
 and below-ground (soil) effects of C. galianoi on the most frequent
 subordinate species, Festuca indigesta, as well as the reciprocal effects
 of F. indigesta on C. galianoi. 3. We performed observational and
 manipulative experiments to assess the influence of phenotypic differences
 of the shrub on understory microhabitat and subordinate plant community
 composition. Reciprocal effects were assessed by removing either F.
 indigesta from the understory of the two shrub phenotypes or the C.
 galianoi canopy from the immediate vicinity of F. indigesta. 4. The two C.
 galianoi phenotypes differed in mean values of functional traits (like
 stem density or plant height), modified their understory microhabitats
 differently, and hosted distinct subordinate communities. Loose phenotypes
 had more positive effects on community composition and diversity than
 tight phenotypes. Additionally, tight phenotypes simultaneously showed
 both more positive aboveground and more negative belowground effects on F.
 indigesta than loose phenotypes. There were no significant feedback
 effects of F. indigesta on C. galianoi. 5. The two phenotypes of the
 foundation species C. galianoi showed contrasting effects on the
 subordinate plant community: compared to the tight phenotype, the loose
 phenotype had higher associated species diversity and reduced reciprocal
 interaction intensities above- and below-ground with the subordinate
 species F. indigesta. This highlights the impact of phenotypic variation
 for plant interactions and community-level diversity.
description: Piston_et_al_2018_Data.zipAll data used to assess whether two contrasted canopy phenotypes (tight and loose) of the shrub Cytisus galianoi differed in their effects on the microhabitat and on subordinate plant community composition in a dry subalpine system. We also experimentally distinguished the relative contribution of above- (canopy) and below-ground (soil) effects of C. galianoi on the most frequent subordinate species, Festuca indigesta, as well as the reciprocal effects of F. indigesta on C. galianoi.Pistón_et_al_2018_Data.zip