The current challenges facing large-diameter timber forests include low yield and low eco-economic benefit. As a result, the development of large-diameter timber forests has become one of the most important strategies for the development of forestry in China. The present study employed bibliometric analysis and Citespace software v.6.1.R3 to examine the literature from CNKI and WOS databases spanning 2002–2021. This analysis aimed to identify the research hotspots and trends in large-diameter timber trees while providing theoretical support and guidance for developing large-diameter timber forests. The research results showed the following data. (1) The number of articles published increased year by year, approximately 4.8 times in 20 years. (2) The journal “Forest Ecology and Management”, where the number of papers is up to 53, has a significant impact on the field of large-diameter timber research. The Tropical Forestry Experimental Center of the Chinese Academy of Forestry and the Wageningen University and Research in the Netherlands possess strong research capabilities, with average citation frequencies of the articles of 26.8 and 51.5, respectively. (3) Research on large-diameter trees focuses on “large-diameter timber cultivation technology and cultivation measures”, “forest conservation management”, “large-diameter timber stand structure”, and “dynamic monitoring of large-diameter timber growth”. “Selection of suitable seed sources”, “Innovation of large-diameter timber cultivation technology”, and “improvement of large-diameter timber forest management mode” are the future research trends of large-diameter trees. In the future, it will be a challenge to realize the sustainable development of large-diameter timber resources. Concurrently, long-term monitoring and scientific management of large-diameter timber forests will be a key issue in promoting the development of large-diameter timber forests.

In recent years, the cultivation techniques of large-diameter forests have garnered increasing attention due to their significant ecological and economic values. However, the effects of small-scale latitudinal changes on the species distribution and community composition of large-diameter trees remain poorly understood. This study aims to investigate the effects of narrow latitudinal gradients on the species composition and structure of large-diameter forests. Investigating these impacts provides critical insights for silvicultural species selection and forest structure optimization, particularly in the context of global warming, and is essential for the sustainable development of large-diameter forests. In this study, three forest communities along a small-scale latitudinal gradient in subtropical China were selected to study the community structure of large-diameter trees by analyzing species composition and species diversity. The community structure was also studied by analyzing species rank curves, the diameter structure, PCoA, MRPP, and indicator species. The results revealed that as latitude increased, the proportion of rare species rose from 43.8% in LL (low-latitude) to 63.2% in HL (high-latitude) areas, while the stem density of dominant species and the number of stems per species also increased. Additionally, species composition homogeneity decreased (based on PCoA and MRPP analysis), age-class structures became more complex, and the proportion of tropical genera gradually declined, whereas temperate genera increased. These findings indicate that small-scale latitudinal variation is a key driver of changes in the composition and structure of large-diameter forests. Currently, the northern Guangdong region is suitable for large-diameter forest development, with Fagaceae species (particularly Castanopsis and Lithocarpus) showing high potential. Specifically, Castanopsis eyrei, Castanopsis fissa, and Ternstroemia gymnanthera are well-suited for large-diameter stand cultivation in Guangdong. For mixed large-diameter forests, Machilus chinensis, Cinnamomum porrectum, and Schima superba are recommended as optimal associated species. However, as global warming progresses, the suitability of tree species for afforestation may shift, necessitating adaptive management strategies.