关键词: 叶际, 根际, 增温, 细菌群落

Abstract: Aims Leaf and root are sensitive to environmental changes. There are many studies about the responses of leaf and root to climate warming, but the effects of warming on phyllosphere and rhizospheric soil bacterial communities remains unclear. Methods The dominant species (Picea asperata and Fargesia nitida) of subalpine coniferous forest in the eastern Qingzang Plateau were selected, and the compositional and functional characteristics of the phyllosphere and rhizosphere soil bacterial community between the two plants and their responses to simulated warming were studied. Important findings The results showed that the Chao index and Shannon index of bacterial communities in rhizosphere soil were significantly higher than those in phyllosphere of both plants. The bacterial diversity in P. asperata were decreased by warming, but that in F. nitida were increased under warming conditions. There were significant differences in bacterial community composition and structure between phyllosphere and rhizosphere. Rhizobiales (41%–46%) were the dominant order of phyllosphere bacterial community, and Vicinamibacterales were the dominant bacterial order in rhizosphere soil. The relative abundance of Burkholderiales and Corynebacteriales increased by about 2 times in P. asperata phyllosphere, and Acidobacteriales in F. nitida phyllosphere were also increased under warming conditions. However, the rhizosphere bacterial community composition of the two plants were less affected by warming. The complexity of rhizosphere bacterial co-occurrence network was higher than that of phyllosphere in both plants. The number of links in co-occurrence networks of P. asperata phyllosphere and rhizosphere bacterial community were increased by warming, but this index was decreased in F. nitida phyllosphere and rhizosphere under warming conditions. According to FAPROTAX, the relative abundance of bacterial groups involved in carbon cycling and nitrogen fixation in rhizosphere were significantly higher than those in phyllosphere. The predictive functions of phyllosphere bacteria were more sensitive to warming than those of rhizosphere, and warming increased urealysis function of phyllosphere bacteria community of both plants, but significantly decreased the phyllosphere predictive functions of nitrogen respiration, nitrate reduction and nitrate respiration in F. nitida and the nitrogen fixation of P. asperata phyllosphere bacteria community. Therefore, there were significant differences in structure and function of bacterial community between rhizosphere and phyllosphere, and the phyllosphere bacterial community was more sensitive to warming than those in rhizosphere soil.

Key words: phyllosphere, rhizosphere, warming, bacterial community