Data from: What makes a leaf tough? Patterns of correlated evolution between leaf toughness traits and demographic rates among 197 shade-tolerant woody species in a neotropical forest

Slow-growing juveniles of shade-tolerant plant species are predicted to
have tough leaves because of the high cost of leaf replacement in shade
relative to potential carbon gain. We assessed the degree of correlated
evolution among eight traits associated with leaf toughness and their
relationships with growth and mortality rates of 197 tree and shrub
species from the understory of the 50-hectare forest dynamics plot on
Barro Colorado Island, Panama. Path analysis with phylogenetically
independent contrasts revealed that leaves attained material toughness
(resistance to fracture per unit fracture area) through increases in
tissue density, percent cellulose per unit dry mass, and vein fracture
toughness. Lamina density and cellulose content evolved independently, and
thus represent different paths to material toughness. Structural toughness
(resistance to fracture per unit fracture length) depended on material
toughness and lamina thickness. Mortality rates of individuals 1-10 cm in
stem diameter were negatively correlated with material toughness and
lamina density, but were independent of structural toughness and cell wall
fiber contents. Leaf toughness traits were uncorrelated with relative
growth rates. These results imply that material toughness enhances
resistance to natural enemies, which increases survival and offsets the
biomass allocation cost of producing tough leaves in the shaded
understory.