关键词: 凋落物, 化感作用, 土壤真菌, 树木幼苗, 百山祖25公顷森林样地

Abstract: Aims The Ericaceae family encompasses a taxonomically diverse, geographically widespread group of plant species. Many members of the family exhibit allelopathy, releasing biochemical substances that suppress growth and development of neighborhood tree seedlings. This advantage facilitates the formation and persistence of Ericaceae-dominated plant communities. Currently, research on the allelopathy of Ericaceae plants affecting regeneration of forest trees remains insufficient, highlighting the need for further exploration. This study sought to elucidate the causes of constrained tree seedling regeneration within the 25-ha forest dynamics plot in Baishanzu, Zhejiang Province. Methods Rhododendron latoucheae, the dominant species in the Baishanzu plot, was selected as the research subject. Aqueous extracts of Rhododendron latoucheae litter (at 1:10, 1:30, 1:50 and 1:100 w/v) were added onto the pots in which seedlings of R. latoucheae, Schima superba, and Neolitsea aurata var. undulatula were planted. By investigating the allelopathic effects of R. latoucheae litter on the growth of these tree seedlings, we aimed to identify the potential factors impeding seedling regeneration in this plot. Important findings (1) The physiological responses of seedlings to treatment with leachate extracted from fallen leaves of R. latoucheae exhibited variability among different tree species. At the concentration of 1:30, the extract significantly improved the superoxide dismutase activity of S. superba but significantly decreased that of N. aurata var. undulatula; (2) The addition of litter aqueous extract exhibited significant effects on the diversity of soil fungi. Specifically, the 1:10 extract significantly increased soil fungal α diversity of both R. latoucheae and S. superba seedlings. Additionally, the differences in fungal β diversity were significant under different treatment concentrations; (3) A significant correlation existed between the leaf area and root traits of tree seedlings and the relative abundance of dominant fungal phyla and genera in the soil. Specificity in soil fungal communities was observed at the phylum level, while at the genus level, key functional genera regulated the physiological and growth strategies of the seedlings. These results indicate that the application of R. latoucheae leaf litter extract significantly affected the traits and physiological characteristics of the tested seedlings. Furthermore, these changes in seedling traits and physiological characteristics showed a significant correlation with the composition of the fungal community in the soil where the seedlings were grown. This finding provides a scientific basis for promoting the regeneration and management of seedlings in subtropical forests where Ericaceae plants are dominant communities.

Key words: litter, allelopathy, soil fungi, tree seedlings, Baishanzu 25-ha forest plot