Abstract: Lianas constitute a crucial component of biodiversity in tropical forests, yet the extent of their diversity and spatial distribution patterns in the north tropical karst forest remains poorly understood. In this study, we investigated the diversity and spatial distribution patterns of lianas within a typical Saraca dives community in the northern tropical karst seasonal rainforest of Nonggang, Guangxi. We elucidated the diversity distribution patterns of lianas and explored the disparities in spatial distribution patterns among distinct taxonomic groups based on 100 quadrats, each measuring 10 m×10 m in a 1 hm² plot. We found that: (1) In the 1 hm² Saraca dives community, 52 species of woody lianas were identified, belonging to 25 families and 43 genera. They represented 55.32% of the total woody species. Furthermore, the Simpson index for lianas was 0.909, the Shannon index was 2.842, and the Pielou evenness index was 0.723. These indices collectively indicate a relatively high level of diversity within the community. There was clear presence of dominant and endemic species. Fabaceae and Vitaceae families stood out for their remarkable species richness and abundance, respectively. Tetrastigma planicaule was the dominant species, with the highest importance value. Furthermore, endemic species constituted 34.61% of the total species number. (2) Lianas demonstrated an aggregated distribution within the spatial scale ranging from 0 to 25 m. Upon removing habitat heterogeneity via the heterogeneous Poisson null model, lianas tended towards a random distribution pattern as the spatial scale increased. When habitat heterogeneity was eliminated, over 70% of liana species exhibited varying patterns of random distribution across specific spatial scales. However, at finer scales, these species still exhibited aggregated distributions. These findings suggest that both habitat heterogeneity and dispersal limitations may influence the spatial distribution patterns of lianas. The observations suggest that both habitat heterogeneity and dispersal limitations may influence the spatial patterns of lianas. Furthermore, there was a negative correlation between the aggregation of lianas and their abundance, as well as their average and maximum diameters at breast height. Notably, lianas with a climbing efficiency of 2 (stem twining) exhibited a higher degree of aggregation. The community of Saraca dives exhibited remarkable diversity in lianas, served as a crucial component of the community. Additionally, the spatial distribution pattern of lianas was not solely related to habitat heterogeneity, but was also influenced, to some extent, by intrinsic attributes such as climbing efficiency and mode. This study lays a crucial foundation for examining the maintenance mechanisms of species diversity in typical forest communities, as well as assessing the impact of lianas on forest carbon storage and dynamic processes.

Key words: lianas, seasonal rainforest, species diversity, spatial distribution pattern, Nonggang Nature Reserve