Permafrost thawing drives long term changes in plant species composition at the Tibetan Plateau

Abstract Permafrost soils contain nearly twice as much carbon as the atmosphere. The current observed climate warming will lead to widespread degradation of near-surface permafrost, which may perturb the vertical distribution of nutrition availability in permafrost-affected ecosystems, and the potential ramification is far-reaching to the carbon cycling between vegetation and climate. Aims: A better understanding of permafrost thawing how to drive plant growth and species composition is crucial for predicting the consequence of climate change for permafrost affected ecosystem response. Methods: We explored the relationship between permafrost thawing, soil chemistry, soil nutrition, and above-ground biomass, maximum rooting depth and species composition across space, and over four decades of warming at 14 Tibet Plateau sites. Results: 1) With permafrost thawing, both cation and anion concentration increased at the ground surface layer (0-50cm); 2) Particularly, nitrogen released from permafrost table stimulated maximum root depth, which drove the species composition; 3) Above-ground biomass in the long term (Fourth decades) did not have a statistic change, although in some special-specific years had a significant fluctuant. Conclusions: Here, we provided suggestions that deep-rooting species have a competitive advantage than shallow-rooting species driver the species composition under climate warming. Whereas, our findings highlight the water-soluble salt (nutrient) concentration and location varieties intense the competitive advantage of deep-rooting species due to short the time of the belowground growing season.