关键词: 外来植物, 火炬树, 生物入侵, 化感作用, 化感适应性, 群落入侵抵抗力, 优势树种

Abstract: [Objective] Studies of human-mediated introductions of organisms and resistance of communities to plant invasion has become one of the central issues of invasion ecology. In this study, we explored variation among dominant tree species from different communities in their resistance to exotic plant Rhus typhina. It will help us understanding the mechanisms underlying invasion resistance of plant communities. [Method] Quercus acutissima, Robinia pseudoacacia, Pinus densiflora, and P. thunbergii are common dominant species in hilly reas of Shandong Peninsula. Laboratory bioassays experiments were conducted to evaluate the allelopathic effects of litter leachates from 4 dominant tree species on the germination rate and seedling growth of R. typhina. In soil medium, chemical compounds can function directly or with the help of soil biota. To further elucidate the effects of 4 dominant trees on total biomass and biomass allocation of R. typhina seedlings, pot experiments with litter addition were done in greenhouse in Ludong University. [Result] Our results indicated that compared to treatments with litter leachates from R. pseudoacacia, P. densiflora and P. thunbergii, the litter leachates from Q. acutissima reduced the germination rate and seedling growth of R. typhina in laboratory bioassays. Likewise in pot experiments, the total biomass of R. typhina seedlings was inhibited when treated with Q. acutissima litter. Compared to treatments of the other 3 species, the leaf mass ratio of R. typhina decreased, the root mass ratio and root to shoot ratio increased with Q. acutissima litter addition. [Conclusion] Q. acutissima showed strong inhibitory allelopathic effects on R. typhina. It can be a new way to control the spread of R. typhina by building high resistance plant communities with Q. acutissima. And we could further screen effective allelochemicals from Q. acutissima to control the growth of R. typhina. Our results revealed that the dominant trees exerted different inhibitory effects on the performance of R. typhina, implying that the allelopathy of some dominant trees may play an important role in determining the community resistance to invasion. This study has important theoretical and practical implications for understanding the invasion processes and the risk-assessment and management of exotic plant invasions respectively.

Key words: exotic plant, Rhus typhina, biological invasion, allelopathy, allelopathic adaptation, community resistance to invasion, dominant tree species