Abstract
Rhododendron nymphaeoides belongs to the Fortunea subsection of the Rhododendron genus. Despite being officially listed as an endangered species (with the conservation status of EN) by the International Union for Conservation of Nature Red List, The Red List of Rhododendrons, Red List of China's Higher Plants, and the Threatened Species List of China's Higher Plants, little is known about this species' community characteristics and population dynamics. This lack of knowledge hampers the conservation and management of its wild resources. This study was conducted on all existing distribution points of R. nymphaeoides through field investigations, revealing the species composition and community structure of its populations. This included analyzing the diameter class structure, creating life tables and survival curves, and analyzing population dynamics indices to shed light on the dynamics of the R. nymphaeoides populations. The results showed: (1) the four communities collectively comprise 122 species of vascular plants belonging to 55 families and 79 genera, with tropical elements predominantly influencing the community structure and environmental formation. Community IV exhibited the highest species diversity, Community III had the most even distribution of species, and Community II had the lowest species diversity. (2) A total of 288 R. nymphaeoides individuals were recorded, showing a spatially clustered distribution. (3) The age structure of the HSC population exhibits a reverse J-shape, indicating a growing population, but there are still constraints in the transition from seedlings to saplings; the LSK population has a substantial number of young individuals and the highest proportion of middle-aged individuals, characterizing it as a stable population; whereas the LZH and HTS populations have few young individuals and a high proportion of middle-aged individuals, with an age structure that is spindle-shaped and trending toward aging, placing these populations at significant risk of decline. (4) The survival curves for all four populations were of the Deevey-II type, characterized by high mortality rates among seedlings. (5) The primary reasons for the difficulty in population renewal and development are the extremely low natural germination rates of seeds, weak competitiveness of seedlings, growth restricted to limestone mountain areas above 1500 m with thin soil layers, and frequent human disturbances. Therefore, conservation strategies that integrate in situ conservation, ex situ conservation, and reintroduction are recommended. Emphasis should be placed on long-term monitoring of R. nymphaeoides populations and communities, enhanced management during the sapling stage, and efforts in seedling propagation and population restoration to achieve population strengthening and the natural reintroduction of artificially cultivated populations, thereby maintaining the population in a healthy state.