Uneven distributions of unique species promoting N niche complementarity
explain the stability of degraded alpine meadow
Abstract
Alpine meadow degradation, usually involving decreased soil N and patchy
landscapes, is challenging for natural restoration. However, the
mechanism underlying plant species coexistence during degradation is
unclear. In this study, we evaluated plant N niche complementarity in
degraded alpine meadows by a 15N-labeling (15NO3-, 15NH4+ and
15N-glycine) experiment. At the community level, the degraded alpine
meadow showed larger root and all plant 15N concentrations and preferred
glycine over NO3- compared with the undegraded alpine meadow. At the
species level, dominant species in the undegraded alpine meadow
consistently preferred NO3-. For the degraded alpine meadow, generalist
species, common to both meadows, showed diverse preferences, while
unique species generally preferred glycine, among which the uneven
distribution could reduce glycine competition. We observed that
differentiation in N sources and the uneven distribution of unique
species may explain the stability of degraded alpine meadows. Our
results suggested that plant spatial distribution could be powerful for
community stability and emphasized the importance of considering
fine-scale perspectives in studies of niche theory. This study have
important implication for restoration of degraded alpine meadows.