Relationships between the timing of budburst, plant traits, and distribution of 24 coexisting woody species in a warm-temperate forest in Japan.

PREMISE OF THE STUDY: Timing of budburst (DBB) may be related to the functional traits and distributions of woody species in temperate regions. Although many previous studies have investigated DBB in a number of temperate species, it has seldom been linked to multiple plant trait relationships.

METHODS: DBB and plant traits were investigated for 24 woody species for 2 years in a warm-temperate secondary forest in Japan. Particular attention was paid to differences in trait relationships between coexisting deciduous and evergreen broad-leaved species.

KEY RESULTS: DBB was correlated with plant traits in deciduous but not evergreen broad-leaved species; DBB was later for deciduous species with greater leaf mass, leaf area, vessel diameter, and leaf nitrogen content per unit mass. In addition, DBB was later for species with more northern distributions in deciduous and evergreen species.

CONCLUSIONS: Clear differences in the trait relationships between deciduous and evergreen broad-leaved species might be caused by different selection pressures on DBB; selection is expected to be more severe in deciduous species. Overall, the continuous variable of vessel diameter might be used as a simple and effective trait to predict DBB of deciduous species regardless of wood anatomy; however, no such traits were detected as effective predictors of DBB in evergreen species at this study site. In addition, DBB was earlier for the species of more southern distributions, suggesting that such species benefit more from warming.