In the current context of biodiversity erosion, functional approaches have emerged to study community assembly mechanisms and to better predict the fate of plant species. Assessing patterns of trait variation should be a powerful tool to determine community assembly mechanisms. Yet, studies on trait variations and their consequences on individual performance are usually incomplete as they focus on a single ecological scale or filter, and do not include relationships between traits, resulting in a fragmented view of plant community assembly. We focused on the macrophyte communities living in particular freshwater ecosystems i.e. the ponds of the Iles Kerguelen, in the sub-Antarctic region. We measured different categories of traits (aerial, root, and clonal) on all occurring species to study trait variations across years, sites and phylogeny scale (between species and within species), and in response to multiple habitat abiotic and biotic variables. The consequences of these traits variations and the effects of their correlations for plant individual performance were also explored. Our results first highlighted a filter operating on the overall distribution of trait values within the region, whereas we observed a high amount of intraspecific trait variation allowing individuals to better resist to filters. Second, traits responses to biotic and/or abiotic factors were trait-dependent, and this combination of simultaneous trait responses should allow the plant as a whole to face several simultaneous constraints. Lastly, almost all traits have either direct or indirect effects on individual performance. As a conclusion, partitioning trait variance is a relevant approach to detect at which scale operate the most decisive processes in plant community assembly without scale dependency issues, and then orient further researches. Furhtermore, we plead to consider multi-traits approach, and several biotic and abiotic variables in future studies to better understand the effects of environmental changes on plant communities.