Abstract: Data on tree biomass are essential for evaluating carbon sequestration cycling, plant adaptations to the environment and also for studying impacts of silvicultural practices on forest productivity. We determined biomass accumulation and allometric relationships in the partitioning of above ground biomass between stems, twig, and leaves in Salix psammophila, a sandy shrub, it not only protects environment, but also has economic value. The biomass allocation patterns were studied by fitting allometric functions in biomass partitioning between leaves (ML), stems (MS) and twigs (MT). The results showed that: (1) Biomass accumulation varied with branch basal diameter (BBD) and branch lengths (BL) increased, and BBD has a higher coefficient of determination in the form of power functions, and the allometric biomass equations for stems, twigs, leaves and of all were y=0.1861x^2.2950, y=0.0194x^2.9794, y=0.0875x^2.1421 and y=0.1863x^2.5454, respectively. (2) The number of the resources allocated to stem, twigs and leaves were changed with branches growing. There showed the power functions better with BBD than BL which the percentages of resource allocated to stem and leaves, and the percentages of twigs biomass to total biomass was better with BL. (3)There existed an allometric relationship between the MS, MT and ML, with the standardized major axis slopes were 1.557 (α_T-S), 1.087 (α_L-S) and 0.6916 (α_L-T), respectively. The twigs have the highest values which increasing with the branches growing, and the stem has the lowest values of that. Therefore, our results indicated that the optimal partitioning theory and metabolic scaling theory complement each other, and it can explain the biomass changed and the scaling relationship for stem, twigs and leaves in S. psammophila branches.

Key words: Salix psammophila, biomass allocation, body size, allometric growth, Mu Us Sandy Land