Niche characteristics of dominant populations in Betula fujianensis J. Zeng, Jian H. Li & Z. D. Chen natural forest

This study investigated the niche characteristics and interspecific relationships among dominant species at different levels within the Betula fujianensis J. Zeng, Jian H. Li & Z. D. Chen community in Luobuyan Nature Reserve of Sanming City, Fujian Province, China, to inform conservation and restoration strategies. Based on sample plots, both niche breadth and overlap of the dominant populations in the tree, shrub, and herbaceous layers of the B. fujianensis community were quantitatively analyzed using Levins and Shannon-Wiener niche breadth and Levins niche overlap indices, respectively, with cluster analysis subsequently carried out based on niche overlap. Results showed that: (1) B. fujianensis and Phoebe bournei (Hemsl.) Yang were the dominant species in the tree layer, followed by subdominant species Ilex formosana var. macropyrena S. Y. Hu, Rhododendron championiae Hooker, and Machilus versicolora S. K. Lee et F. N. Wei. Sarcandra glabra (Thunb.) Nakai, Eurya loquaiana var. aureopunctata Hung T. Chang, and Eurya weissiae Chun were the dominant species in the shrub layer, while Plagiogyria adnata (Bl.) Bedd., Nephrolepis cordifolia (L.) C. Presl, and Woodwardia japonica (L. f.) Sm. were the dominant species in the herbaceous layer. (2) Niche overlap of the main species in the tree layer was relatively low, with only 62 species pairs (19.1%) showing a high degree of overlap, while 12.3% of species pairs showed complete niche separation, indicating no intense interspecific competition in this layer. Conversely, 236 species pairs (67.2%) showed high niche overlap in the shrub layer, while only four species pairs showed niche separation, indicating that most shrub layer plants had similar or common resource needs. In the herbaceous layer, 43 species pairs (22.6%) exhibited a high degree of niche overlap, while 39 species pairs showed niche separation, suggesting distinct resource niches and coordinated interspecific relationships. (3) Based on niche overlap, cluster analysis revealed that species in the different layers of the B. fujianensis community were clustered together, with the tree and shrub layers divided into four groups and the herbaceous layer divided into three groups. Overall, results indicated that the B. fujianensis community demonstrated high stability. These findings have important theoretical and practical value for guiding the protection and restoration of B. fujianensis communities.