The Effects of Experimental Warming on Phyllosphere Microbial Communities of Picea asperata and Fargesia nitida in Eastern Tibetan Plateau, China.

Phyllosphere microbiomes play a crucial role in leaf physiological functions, yet their responses to climate warming remain unclear. In this study, we examined the effects of a 3-year experimental warming on the composition and potential functions of phyllosphere bacterial and fungal communities, as well as leaf physiochemical properties of two dominant species (Picea asperata and Fargesia nitida) in the eastern Tibetan Plateau. The results indicated that the phyllosphere bacterial diversity in P. asperata was higher than in F. nitida, but the fungal diversity showed no significant difference between the two species under unwarmed conditions. Warming decreased bacterial and fungal diversity in P. asperata, while increased these parameters in F. nitida. The compositions of the phyllosphere microbial community differed between the two species (p < 0.05), but Rhizobiales and Capnodiales remained the dominant orders within the bacterial and fungal community for both species, respectively. The bacterial community composition of P. asperata needles and the fungal community composition of F. nitida leaves were more sensitive to warming. Additionally, the two species exhibited significant differences in most leaf physiochemical properties, including leaf water content, C, N, P, and photosynthetic pigment content (p < 0.05). The compositions and predictive functions of the phyllosphere microbial communities were significantly correlated with the leaf physiochemical properties. In summary, phyllosphere microbial communities and their responses to warming were significantly affected by host plant species and were closely related to the distinct physiochemical traits of their leaves.