Vegetation and soil stoichiometry characteristics of degraded alpine meadows in the source region of the Yangtze River

We explored the effects of alpine meadow degradation on the stoichiometric characteristics of carbon (C), nitrogen (N), and phosphorus (P) in both vegetation and soil, along with the stoichiometric homeostasis of plant N and P. The research centered on intact, moderately degraded, and severely degraded alpine meadows in the permafrost region at the source of the Yangtze River. We measured the contents of C, N, and P in the vegetation and soil of alpine meadow plant communities with different degrees of degradation and analyzed their stoichiometric ratios and the stoichiometric homeostasis of the plant communities. Our aim was to provide a scientific basis for regulating the vegetation restoration of degraded alpine meadows. Our results demonstrated that as the degradation intensified, the plant community leaf C and N contents first decreased and then increased, soil C and N contents decreased, leaf P content increased, and soil P content decreased and then increased. Moreover, the leaf N:P ratio of the plant community in both intact and severely degraded stages exceeded 16, indicating that plant growth in these stages is limited by P, while the moderately degraded plant community’s leaf N:P ratio fell under 14, indicating that plant growth in this stage is limited by N. Additionally, the N:P ratio of dominant species in the alpine meadows of the same degradation degree were markedly different, indicating that different nutrients restrict the growth of different species in the community. Finally, the plant leaf N and N:P ratio exhibited homeostasis, while plant leaf P showed a strict homeostasis. Our results demonstrate that plant growth tends to be restricted by P in the intact and severely degraded stages, but by N in the moderately degraded stages. In the alpine meadow plant communities in permafrost regions, both N and P in plant leaves exhibit strong stoichiometric homeostasis.