Abstract: Biomass allocation patterns reflect the strategies of plants adapting to various habitat conditions and play a vital role in global terrestrial carbon cycling. With seedlings of tree species (Machilus pauhoi, Cerasus campanulata and Fokienia hodginsii) belonged to three functional types as research objects, we used the standardized major axis estimation to test biomass allocation patterns, and used the correlation analysis to analyze its relationships with carbon (C), nitrogen (N), phosphorus (P) contents in fine roots and leaves. The results showed that allometric relationships between stem biomass and leaf biomass, root biomass and leaf biomass, as well as stem biomass and root biomass, indicating the importance of stem for biomass allocation of M. pauhoi. There were isometric relationships among leaf, root, and leaf biomass of both C. campanulata and F. hodginsii. The scaling exponents of the seedlings of the three species did not differ signifiacntly, with a common slope of 1.05 (95% CI=0.97-1.14), indicating that aboveground biomass scaled isometrically with belowground biomass. The relationships between fine root C, N and P contents and biomass allocation of the three species were as follows: Fine root C contents were positively correlated with stem mass ratio only in F. hodginsii. Fine root N contents were positively related to leaf mass ratio in M. pauhoi. Fine root N contents were negatively correlated with leaf mass ratio, and positively correlated with root mass ratio in C. campanulata. Fine root N contents were positively correlated with stem mass ratio of F. hodginsii. Fine root P contents were positively correlated with leaf mass ratio, and negatively correlated with root mass ratio and root-shoot ratio only in M. pauhoi. Fine root N∶P and stem mass ratio exhibited negative relationship in M. pauhoi. However, fine root N∶P was not correlated with biomass allocation in C. campanulata and F. hodginsii. The relationships between leaf C, N, P and biomass allocation of the three species were as follows: leaf C contents were negatively correlated with leaf mass ratio in M. pauhoi. Leaf N contents were positively correlated with stem mass ratio in C. campanulata. There was no significant relationship between leaf C contents and biomass allocation in F. hodginsii. Leaf P contents were positively correlated with stem mass ratio in only M. pauhoi. Leaf N contents and N∶P were not correlated with biomass allocation of the three tree species. Generally, the above and below ground biomass allocation patterns of the three tree species were in consistence with the isometric biomass allocation theory. However, they did not show the same allometric relationships among different organs, and the relationships between biomass allocation and leaf and fine root C, N, P contents were also different. The results indicated that different plant functional types can adapt to environment by adjusting biomass allocation patterns, which provided scientific reference for efficient cultivation of seedlings from different functional types.

Key words: functional type, biomass allocation, allometric relationship, nutrient content, leaf, fine root, tree seedling.