Abstract: Whether the species diversity (SD) in natural ecosystem varies wit h functional diversity (FD) and consequently affects the primary productivit y is still an open question. In this paper, a field grazing experiment was condu cted on an alpine Kobresia humilis meadow to study the effects of SD and FD on t he primary productivity of the ecosystem. Four habitats with different grazing i ntensity and soil nutrient availability were selected, i.e., pen pasture with he avy grazing intensity and highest nutrient availability, pass pasture with moder ate grazing intensity and moderate nutrient availability, artificial pasture wit h light-moderate grazing intensity and lower nutrient availability, and un-gra zed pasture with null grazing intensity and lowest nutrient availability. Among the test habitats, pass pasture had the highest SD, which fitted intermediat e disturbance hypothesis. Artificial pasture had low SD but the highest FD , while un-grazed pasture had higher SD and FD. There was a positive relationship between SD and primary productivity but a negative relationship between FD and primary productivity, suggesting that FD didn’t vary wi th SD, and, to a definite extent, both SD and FD could affect the pr imary productivity independently. Habitat resources, species charact eristics, grazing history, and grazing intensity affected the community’s prima ry productivity and biodiversity in an integrative way.

Key words: Lake, Ecosystem dynamics, Modeling