Correlations between leafing phenology and traits: Woody species of evergreen broad-leaved forests in subtropical China

Leaf phenology has been considered to evolve to maximize plant carbon gains, and it reflects plant life history strategies. To determine the effect of leaf traits on leaf phenology, leaf emergence (such as timing of leaf emergence, leaf expansion rate, durations of leaf expansion), leaf traits (leaf mass per area - LMA and leaf size), and their relationships were investigated for 40 woody species from 13 families in an evergreen broad-leaved forest, southeast China. Compared with understorey shrubs (23 species), trees species (17 species) were significantly later in timing of leaf emergence, greater in leaf area and leaf expansion rate. This is assumed to be a strategy for large-leaved tree species to decrease damage during leaf expansion. In terms of leaf size, the small-leaved species leafed out earlier than the species with large leaves, but the large-leaved species were greater in leaf expansion rate than their counterparts. Leaf expansion rate was positively correlated with leaf area and timing of leaf emergence. Leaf herbivore rate was positively correlated with leaf area and leaf expansion period, but negatively with LMA. These results suggest that large-and small-leaved species possibly employed different strategies to minimize herbivore damage. Small-leaved species avoid defoliator damage by early leafing, while large-leaved species have shorter expansion times and thereby shorten vulnerable time to herbivores. In general, dynamics of emergence and expansion of the woody species in the study forest indicate that the leaf phenology is of significance for species' carbon gain and survival.