A importância da especificidade nas interações entre plantas para comunidades semi-áridas

Abstract

Plant-plant interactions play an important role modulating plant communities. In stressful environments, positive interactions between benefactor (nurse) and beneficiary (target) plant species are commonly reported, but negative relations are still present. Considering that one nurse plant can interact with multiple target species, the outcome of each interaction might vary from negative to positive generating a range of species-specific relations that are difficult to predict. Nurse traits might indicate their capability to deploy or improve abiotic resources, where species with slow traits, or stress-tolerant, may keep resources available longer than plants with fast traits, or competitors. This work aims to understand (i)How plant-plant interaction outcomes vary with species identities combination and (ii) if nurse functional traits can predict positive or negative interaction outcomes between nurse and target species. We conducted a multi-species factorial experiment planting 3 targets-species below and far from the canopy of 20 nurse-species, using 5 replicates for each treatment combination. Nurse-target showed ubiquitous species-specific interactions for targets growth, but not for survival. Despite that, nurse species in general had a positive effect on target survivorship. Slow-fast traits did not drive species-specific interactions, however, canopy traits were revealed as good predictor of interaction outcomes for at least one target species. These results suggest that not just nurse traits have to be considered for understanding species-specific effects, but also target strategies for resource use might be a key element to predict plant-plant interaction outcomes.