Leaf trait co‐variation and trade‐offs in gallery forest C3 and CAM epiphytes

Abstract

AbstractDespite their unique adaptations to thrive in canopy environments without access to soil resources, epiphytes are underrepresented in studies of functional traits and of functional composition of tropical plant communities. We investigated functional traits of spermatophytic (seed‐bearing) C3 and CAM epiphyte communities in flooded and non‐flooded gallery forests in Central Brazil. The two forest types differ in floristic, structure, microclimate, and edaphic conditions. We studied plant size, leaf thickness, leaf dry matter content (LDMC), leaf water content, leaf area (LA), specific leaf area (SLA), leaf C, N, P, K, Mg, and Ca, and stable isotope ratios (δ13C and δ15N). Because photosynthetic pathway (C3 or CAM) is an important aspect of ecological differentiation for spermatophytic epiphytes, we expected that functional trait syndromes in a multivariate space would be more associated with photosynthetic pathway than forest type, and changes in abundance of C3 and CAM epiphytes would drive functional trait composition at the community level. C3 and CAM epiphytes segregated in the multivariate trait space; however, more complex functional typologies were also evident. Despite lower light levels, CAM epiphytes were more abundant in the flooded gallery forest. There, they accounted for 80% of all individuals, whereas C3 epiphytes dominated in the non‐flooded forest. These large differences in the proportion of CAM and C3 epiphytes strongly affected functional trait values at the community level, despite very little intraspecific variation in trait values between forest types for species that occurred in both forests.Abstract in Portuguese is available with online material.