Abstract: By using Levins niche breadth index and Cowell similarity index, the niche breadth and niche similarity of main plant species in Bayanbulak alpine meadow were calculated, based on 3 resources dimensions (soil moisture, organic matter, and available K) along four gradients of soil salt content. The results showed that with the increase of soil salt content, the average niche breadth of main constructive species Carex stenocarpa based on the 3 resources dimensions decreased from 0.4433 to 0.1740, while that of companion species Potentilla anserina increased from 0.1263 to 0.2215, indicating that the niche breadth of the species with low salt-endurance decreased gradually, while the species with relatively high saltendurance had an increasing niche breadth, being-able to be an important succession species. With the increase of soil salt content, the niche similarity between the species with low salt-endurance increased, while that between the species with high salt-endurance was in adverse. The niche similarity between C. stenocarpa and Kobresia capillifolia increased from 0.701 to 0.842, and that between P. anserina and Taraxacum pseudolpinum decreased from 1 to 0.708. The difference in biological characters among plant species should be the main reason for their different responses to soil salt content.

Key words: Quercus variabilis, closetonatural forest management, thinning intensity, seed bank, seedling, Qinling Mountains.