Twigs of dove tree in high-latitude region tend to increase biomass accumulation in vegetative organs but decrease it in reproductive organs

Adaptive traits are an important dimension for studying the interactions between rare plants and environment. Although the endangered mechanism of rare plants has been reported in many studies, how their twigs adapt to heterogeneous environments associated with latitude is still poorly known. Dove tree (Davidia involucrata Baill.), a monotypic rare species in China, was employed as a model species in our study, and the differences in functional traits, growth relationships and resource allocation among components of annual twig were investigated in three latitudinal regions (32 degrees 19 ' N, 30 degrees 08 ' and 27 degrees 55 ') in the Sichuan, Southwest China. Compared with low- and middle-latitude regions, the twig diameter in high-latitude region decreased by 36% and 26%, and dry mass decreased by 32% and 35%, respectively. Moreover, there existed an allometric growth between flower mass and stem mass or leaf mass in high-latitude region but an isometric growth in low- and middle-latitude regions. At the flower level, an isometric growth between bract area and flower stalk mass was detected among in three latitudinal regions, and the flower stalk mass in the low-latitude region was higher than in the middle- and high-latitude regions for a given bract area and flower mass. At the leaf level, the growth rate of petiole mass was significantly higher than those of leaf area, lamina mass and leaf mass among three latitudinal regions, and the petiole mass in the low-latitude region was higher than in the other two regions for a given leaf mass. Our research demonstrated that the twigs of dove tree in high-latitude region tend to become smaller, and resource input increase in stems and leaves but decrease in flowers, which reflects that dove tree can adapt to the environmental changes across different latitudes by adjusting phenotypic traits growth and biomass allocation of twigs.

Automated summary

This study investigated the differences in functional traits, growth relationships, and resource allocation of dove tree twigs among three latitudinal regions in China. The results showed that twigs in the high-latitude region were smaller and had decreased flower mass compared to the low- and middle-latitude regions. A different growth relationship between flower mass and stem or leaf mass was observed in the high-latitude region compared to the other regions. The allocation of resources to stems and leaves increased while the allocation to flowers decreased in the high-latitude region. These findings demonstrate that dove tree twigs can adapt to environmental changes across latitudes by adjusting their phenotypic traits and biomass allocation.