Abstract: By measuring the δ¹³C/δ¹⁵N ratios of main plants and their consumers (passerine birds and small mammals) on different altitudes alpine meadow of east Qinhai-Tibet Plateau, this paper studied the characteristics of the consumers’stable carbon and nitrogen isotopes composi-tion and their relationships with the plants’stable isotopes composition and environmental fac-tors. The results showed that the average δ¹³C value of plants increased with increasing altitude,and the stable C and N isotopes composition of the consumers also increased significantly from low to high altitude. Both δ¹³C and δ¹⁵N of passerine birds had obvious increase with increasing alti-tude, while the δ¹³C value of small mammals did not change with altitude, but their δ¹⁵N had a significant increase from low to high altitude. It was suggested that the variation of plants’stablecarbon and nitrogen isotopes composition might be the important factor determining the altitudinal differentiation of the consumers’ stable isotopes composition, and the variation of environmental factors due to the changes of altitude and latitude could partially contribute to the stable carbon and nitrogen isotopes composition of the consumers. Compared with passerine birds, small mam-mals in their metabolic processes of stable carbon and nitrogen isotopes were more sensitive to the changes of the environment.

Key words: Castanopsis kawakamii community, Gap, Species diversity, Edge effect