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Plant functional traits have been recognized as important factors related to the ecological strategies of species in forest ecosystems. We examined the relationships between functional traits and both tree species performance and environmental conditions in a subtropical forest in Brazil. Over four years (2008-2012), we investigated how demographic rates were related to functional traits (wood density, leaf area and tree height) of 20 species sampled within 50 plots of 10 × 20 m, which had previously evaluated as to environmental conditions. Non-metric multidimensional scaling was used to order the species by their functional traits. The demographic rates were fit a posteriori to the ordination, with significant rates (p < 0.05) plotted as vectors. The relationships between environmental conditions and the community-weighted means (CWMs) of trait values were verified using redundancy analysis. CWM wood density was positively correlated with soil pH. CWM leaf area and CWM maximum tree height were both negatively correlated with altitude and positively correlated with soil magnesium (Mg) content. The taller species with lower wood density, which occupied the forest canopy, had a greater diameter increment and lower recruitment than did the shortest species with higher wood density. The shorter species with higher wood density, which occupied the understory, had greater recruitment and a greater increase in abundance than did the taller/lower-wood-density species. Our study (i) revealed changes in the forest related to the light environment, with an increase in the relative participation of shade-tolerant species with higher wood densities, and (ii) detected small-scale spatial variation in community traits as a response to variations in soil chemical properties and topography.

Aims Despite the growing interest in the topic of functional ecology, there are still forest regions that have not been examined, as most work has been done in the tropics. Unresolved issues include the strength of a growth-mortality trade-off in trees (originally identified for seedlings) and the nature of the association between plant traits and vital rates, if any. Our objectives were to examine whether (i) ecological strategies in South American mixed forests are organized along the fast competitor × slow stress-tolerator and height gradients as the main strategy axes depicted in the overall trait and vital rate correlation structure, and (ii) a tentative path model we proposed can explain the patterns of covariation among traits and vital rates. Methods We studied a different habitat (subtropical mixed conifer-hardwood forests) and region (Brazilian Atlantic Forest) from the majority of related studies in forests, carried out in the Neotropical region. Data on total height, stem slenderness, crown depth, wood density, specific leaf area, leaf and seed length, seed dispersal mode, annual mortality, diameter relative growth rate and relative growth rate under favorable conditions were measured in southern Brazil for 66 tree species. Data were subjected to principal components analysis and path analysis. Restricted data on saplings and treelets were analyzed through correlation. Important Findings Studied traits were reduced to four principal components. Principal components analysis produced axes that fit the resource acquisition versus resource-conservation and the height-mortality trade-offs, although the former was split into two distinct axes. Seed size and seed dispersal mode appeared independently of these axes. A path model showed that leaf length and specific leaf area caused direct changes in trunk slenderness and, indirectly through growth, affected mortality. Expected trade-offs between growth and survivorship and between wood density and stem slenderness trade-offs were not found. This may result from the lack of extreme pioneers and over-representation of slow-growing hardwood species found in Atlantic subtropical forests of South America. This suggests that the fastest growing species in the region do not grow so fast as to compromise wood density and survivorship, but grow fast enough to benefit from increased size. Relationships between traits and vital rates seem to be mediated by the assembly process of regional floras, and the relative importance of traits like SLA and wood density may vary between floristic regions. [ABSTRACT FROM AUTHOR]