Efeito das macrófitas no funcionamento de ecossistemas úmidos

Abstract

In this thesis, we explore two distinct mechanisms that influence the functioning of tropical aquatic ecosystems. In Chapter I, we evaluate how the taxonomic and functional diversity of emergent macrophyte communities affects biomass production and nutrient retention. In Chapter II, we investigate how the presence of a native grass species can modulate the morphology and plasticity of an opportunistic species. In Chapter I, we demonstrate that both taxonomic diversity and functional diversity significantly increase biomass production, but the effects are more strongly explained by functional diversity metrics, especially functional richness (FRic). These results indicate that diversity in species’ morphological traits is more important for this process than the simple number of species. On the other hand, none of the diversity metrics directly influenced nitrogen or phosphorus retention, nor ecological multifunctionality measured as the combination of these processes. In Chapter II, we test whether the presence of Leersia hexandra, a native grass, alters the morphology of Commelina diffusa, an opportunistic species commonly found in wet and eutrophic environments. We observed that, although there was no significant reduction in biomass, the native grass modulated the growth architecture of the opportunistic species, leading to greater aerial expansion and wider root spread. These results highlight a potential for functional regulation based on morphological interference, with important implications for agroecological management strategies. The results of this thesis reinforce the importance of considering both the functional diversity of plant communities and species-specific interactions to understand ecological processes in wetland environments. Furthermore, they highlight that functional complementarity enhances productivity, while morphological plasticity modulation contributes to containing the dominance of opportunistic species, underscoring the importance of these mechanisms in regulating ecological processes in wetlands.