Functional diversity in an alluvial atlantic forest

Atlantic Forest alluvial ecosystems experience strong environmental filtering driven by seasonal flooding and hydrological variability, shaping their structure and functioning. This study investigated how leaf and demographic traits organize functional groups and structure functional diversity in an 11.5-ha urban fragment in Guarapuava, Paraná, southern Brazil. We surveyed 103 permanent plots (1.03 ha), assessing 34 species based on six traits (specific leaf area – SLA, leaf length – LL, leaf dry matter content – LDMC, leaf thickness – LT, mortality rate (M), and relative growth rate (RGR)). Functional groups were identified using Ward’s clustering and PCoA, group comparisons were tested using Generalized Linear Models (GLMs), and functional diversity was assessed with FRic, FEve, FDiv, FDis, and RaoQ indices. The community was dominated by Gymnanthes klotzschiana, Ligustrum lucidum, and Matayba elaeagnoides. Clustering revealed four coherent functional groups along the acquisition–conservation axis. The PCoA explained 64.64% of trait variation, highlighting the coexistence of acquisitive species (high SLA, elevated mortality) and conservative species (thicker leaves, reduced mortality), with partial overlap among groups and complementary niches. Overall, the community maintained moderate to high functional diversity (FRic = 4.62; FEve = 0.67; FDiv = 0.79; FDis = 1.33; RaoQ = 2.71). We conclude that both functional redundancy and differentiation underpin the resilience of this system under hydrological variability and anthropogenic disturbance. We propose prioritizing acquisitive species in early restoration phases and conservative ones in advanced stages to optimize resource-use efficiency and ensure long-term ecosystem stability.