Abstract: The variation of branch and leaf traits across plant individuals with different sizes is a canopy building strategy for the adaptation of plants to heterogeneous environment. To examine how twig and leaf traits of Lavandula angustifolia depended on individual size, we conducted an experiment in a three-year-old L. angustifolia plantation in Goldwater Lake Wetland Park, Jinchang, China in late July 2017. Leaf area, leaf thickness, leaf number, twig number, twig length, crosssectional area of twig and bifurcation angle of  L. angustifolia individuals in a 200 m×50 m plot were measured. The plants were classified into three grades based on their volume (size I: d(the cube root of plant volume) ≤60 cm, size II: 60 cm <d≤90 cm, and size III:d>90 cm). Correlation analysis was performed to examine the relationships between twig and leaf traits and individual size. With the increase of plant size, single leaf area, twig number, twig length and twig crosssectional area increased, while leaf number, leaf thickness and bifurcation angle decreased. The leaf area, twig length and number as well as crosssectional area of L. angustifolia were positively correlated with individual size (P<0.05), whereas the leaf number, leaf thickness and bifurcation angle were negatively correlated with individual size (P<0.05). In order to improve the efficiency of resource use, individuals with large size tended to have a large and thin leaves and allocate more biomass to twigs, while small individuals tended to have a small and thick leaves and short, thin twigs. These results reflected the phenotypic plasticity of leaves and twigs for different individual sizes of L. angustifolia.

Key words: community structure, marine ecosystem health, dominant species, fishery resources