| dc.description.abstract | Introduction: In functional ecology, it has long been hypothesised that functional traits can be used to approximate niche differentiation and predict the outcome of plant–plant interactions. However, current research has primarily focussed on aboveground trait frameworks and often relied on mean trait values derived from databases without given resource contexts, leading to ambiguous results. This study adopted the root economics space (RES) from Bergmann et al. (2020) as a trait framework to test this hypothesis and assess the performance of paired RES-based communities.
Methods: A greenhouse experiment was conducted with paired native grassland species grown under drought, nutrient enrichment and their combination. Root traits associated with the RES were measured in monocultures at the species level per treatment. Using those traits, species were positioned in the RES using a principal component analysis, and Euclidean distance was used to quantify trait dissimilarity. The interaction of paired species was assessed relative to monoculture baseline performance.
Results: The PCA confirmed the presence of the RES within the selected focal species, explaining 91.3% of trait variance. However, trait dissimilarity was not a consistent predictor of plant–plant interactions across resource treatments. A marginal interaction effect between trait dissimilarity and resource treatments was observed, driven by a significant negative association under drought conditions only. Fertilisation appeared to be the dominant driver in community productivity, consistently increasing shoot biomass across functional pairing scenarios, whereas drought and its interaction with fertilisation had no significant effect.
Conclusion: These findings suggest that while the RES effectively captures major axes of root trait variation, RES-based dissimilarity alone does not predict the outcome of plant–plant interactions, and its role in doing so may strongly depend on specific resource contexts. Community performance was primarily driven by nutrient enrichment, showing no synergistic, but rather an additive interaction between drought and fertilisation. Future studies may benefit from focussing on holistic trait frameworks that integrate both above- and belowground processes across resource gradients, combined with experimental quantification of traits and intraspecific variability. | |
