Discussion
Our results showed that the N absorption capacity of the degraded alpine meadow was higher than that of the undegraded alpine meadow. N source preferences at the community level differed between the degraded and undegraded alpine meadows, and the N source preference also differed substantially between generalist and unique species. Exist a general shift from NO3- to glycine preference in pass from non-degraded to degraded meadow at community level, whereas at species level we observed that species that are present in both non-degraded and degraded meadow we observed that some species did not change its preferences and other changed it. Thus, the clear changes at community level in N uptake preferences are due to both; some species change in N uptake preferences and also to species turn-over.