Abstract: There are at least species and individuals (genetic structure) redundancy of population within each trophic level of ecosystems. By use of redundancy theory,authors probed into trophic structure and its model.The model for trophic structure combining advantages of food web and those of trophic level could reveal inherent relation between trophic structure and stability of ecosystems. The trophic structure of ecosystems is a huge and complex system with series_parallel redundency. Within each trophic level,individuals of a population and most species are arranged in parallel, but different trophic levels are linked in series way. Redundant property of the trophic structure determines that the ecosystems are stable or resistant and at some times fragile to a degree.

Key words: Oligostachyum lubricum, ecological stoichiometry, nutrient resorption, stand density.