Abstract: Biomass allocation in current-year shoots (twigs) is an important parameter categorizing plant life history strategies, and it is an important driving factor for plant net carbon obtaining. In this study, the scaling relationships of biomass allocation within twigs of evergreen and deciduous species at Gongga mountain were estimated using standardized major axis estimation(SMA) and the phylogenetically independent contrast analysis(PIC) methods. The results indicated: Isometric relationships were found between twig mass and stem mass, leaf mass and lamina mass, as well as between stem mass and leaf mass, suggesting that the biomass allocation to either leaves or laminas were independent of twig mass; allometric relationships were found between petiole mass and leaf mass, as well as between petiole mass and twig mass, indicating the importance of leaf petioles to the within-twig biomass allocation; evergreen species tended to have a greater petiole mass at a given twig or lamina mass than deciduous species. Our results indicate that petioles serve as an adverse forcing on the maximization of lamina biomass and the allometric relationship between lamina and lamina support varies with species type.

Key words: lamina, petiole, twig, biomass allocation, allometry