TThe Juniperus przewalskii forests are a unique forest community in China, widely distributed in the mountains on the northeastern edge of the Qinghai-Tibet Plateau. They play crucial roles in slope protection, soil conservation, water source preservation, and habitat improvement. A systematic study of their distribution, composition, and characteristics can provide a scientific basis for the healthy development and artificial management of Juniperus przewalskii forests, enabling them to better fulfill their ecological role in cold and arid areas. This study conducted a comprehensive survey of Juniperus przewalskii forests throughout the plant growth season from 2018 to 2022. A total of 52 survey sites were selected and 72 survey plots were established, covering the entire distribution area of Juniperus przewalskii forests. The 72 survey plots were analyzed using community ecological analysis methods such as cluster analysis and quantitative statistics. The main findings are as follows: Juniperus przewalskii forests are primarily distributed on sunny and semi-sunny mountain slopes at altitudes of 2800 to 3800 meters, usually inhabit dry, barren, and steep slopes, where the habitat conditions are relatively harsh. The existing forests are mostly climax communities of secondary successional, The forest stands are relatively sparse, with a canopy density of 0.2 to 0.6 and an average height ranging from 5 to 13 meters. The vertical structure consists of tree layer, shrubby layer, and herbaceous layer. The tree layer is dominated by Juniperus przewalskii, and the diameter class structure shows a right-skewed normal distribution, with the diameter at breast height mainly concentrated between 4 to 8 centimeters. The composition of the shrubby and herbaceous layers vary significantly depending on the specific habitat conditions. A total of 370 species of vascular plants have been recorded, distributed among 48 families and 151 genera. Among these, angiosperms comprise 45 families and 148 genera, gymnosperms consist of 2 families and 2 genera, and ferns are represented by 1 family and 1 genus. The top three dominant families are Asteraceae, Poaceae, and Fabaceae. In the composition of life types, there are obviously more herbaceous species than woody species. Based on the dominant and characteristic species of the community, Juniperus przewalskii forests can be further classified into 11 association groups and 25 associations. The spatial distribution exhibits a clear ecological sequence, arranged by altitude from low to high, the sequence includes the Juniperus przewalskii-Berberis diaphana-Herb Association Group, Juniperus przewalskii-Dasiphora fruticosa-Herb Association Group, Juniperus przewalskii-Dasiphora parvifolia-Herb Association Group, Juniperus przewalskii-Dasiphora glabra-Herb Association Group. In areas subjected to significant human disturbance, the community transitions into the Juniperus przewalskii-Herb Association Group.

The Pinus densata alliance is one of the most widespread pine forests in the Mountains of Southwest China. Endemic to China, and the alliance is mainly found in western Sichuan, northwest Yunnan, and southeast Xizang. In this study, we defined the geographic distribution boundary and initially ascertained the geographic distribution area of Pinus densata alliance based on previous literature and field investigation sample sites. Based on data from 48 plots surveyed during 2020–2022, we proposed a preliminary scheme of vegetation classification and described the community structure characteristics for Pinus densata alliance, and analyzed the species composition characteristics combined with data from 11 plots surveyed in 2012. The results showed that: (1) The Pinus densata alliance covers 33 counties and cities, including Yajiang, Xiangcheng, Daocheng, Dêqên, Xamgyi’nyilha , Markam, Mainling, and so on, along altitude ranging from 2 300 to 4 000 m. The eastern, west-ern, northern and southern boundaries are Donggu Town in Danba County, Zengqi Township in Sangri County, Puxi Township in Zamtang County, and Yulong Snow Mountain in Yulong Naxizu Autonomous County. (2) 522 vascular plants belonging to 67 families and 222 genera were recorded, among which there were 500 seed plants belonging to 60 families and 209 genera, and 233 Chinese endemic plants belonging to 42 families and 114 gen-era. The north temperate element was the dominant areal-type. (3) Based on the differences of community struc-ture and species composition, Pinus densata alliance could be classified into 7 association groups and 20 associa-tions.

Keteleeria pubescens is endemic to China and is classified as a national second-class key protected wild plant species. The distribution areas of the Keteleeria pubescens communities are extremely narrow, primarily occurred in patches in mountainous and hilly regions of Guizhou and Hunan provinces. To reveal the spatial distribution, community composition, and characteristics of Keteleeria pubescens forests, this study conducted comprehensive plot surveys of the communities from 2021 to 2023 during the plant growing season. A total of 4 survey sites were selected within the distribution range of Keteleeria pubescens forests, with 11 plots established, covering all distribution areas of the forests. Information on habitat, species composition, and quantity characteristics of all the forests were recorded. The main results of the quantitative analysis are: (1) Keteleeria pubescens forests had a rich species composition, with a total of 102 vascular plant species recorded; (2) Totally classified into 2 association groups and 2 associations, namely, Keteleeria pubescens + Evergreen Broadleaf Tree Association Group and Keteleeria pubescens - Herb Association Group; Keteleeria pubescens+Quercus glauca Association and Keteleeria pubescens - Woodwardia japonica Association; (3) The forests’ vertical stratification is obvious, in the arborous layer there were mainly Keteleeria pubescens and species of Quercus, Castanopsis, and Pinus; (4) The regeneration of Keteleeria pubescens is poor. This study surely provides solid scientific data for effective conservation and management of Keteleeria pubescens forests.

Keteleeria davidiana is a relict and endemic species found in China, and K. davidiana forests are distributed in Shaanxi, Sichuan, Hubei, Hunan, Guizhou and Yunnan provinces. These forests play important roles in soil improvement, water conservation, material and medicinal functions. To provide a scientific basis for the conservation and sustainable utilization of K. davidiana germplasm resources, we obtained data from 48 forest plots where K. davidiana is the primary dominant species through field investigations. Based on the principles of community-ecological classification and the latest revision of the Chinese vegetation classification system, we classified the forests into Association Groups and Associations, and described the characteristics of each Association Group and Association, highlighting their community composition and structure. The main results are as follows: (1) We classified the 48 plots into 3 Association Groups, including K. davidiana - Shrub - Herb Association Group, K. davidiana - Herb Association Group and K. davidiana + broadleaf tree - Herb Association Group, and these three Association Groups were further divided into 7 Associations, including K. davidiana - Myrsine africana - Cyrtomium fortunei Association, K. davidiana - Camellia oleifera - Liriope spicata Association, K. davidiana – L. spicata Association, K. davidiana - Carex breviculmis Association, K. davidiana - Diplopterygium glaucum Association, K. davidiana - Isachne globosa Association, K. davidiana + Liquidambar formosana- Iris confusa Association, (2) In both the K. davidiana - Shrub - Herb Association Group and the K. davidiana - Herb Association Group, K. davidiana was the sole dominant species in the arbor layer. (3) In the surveyed K. davidiana forest, a significant number of young K. davidiana trees were present in the shrub layer, indicating good regeneration. In this study, we provide the original survey data of all plots and specify the sources of existing data.

Tsuga dumosa forests were mainly distributed in the Hengduan Mountains and their extension areas in the southwestern region of China, including Xizang, Yunnan, and Sichuan. The current T. dumosa forests are mainly found in humid mountainous regions and mostly grow on mountain ridges, steep slopes, and along stream banks. These forests experienced varying degrees of disturbances, both natural and anthropogenic. To reveal the spatial distribution, community composition and characteristics of T. dumosa forests, this study conducted systematic field investigation during the plant growing seasons in 2018 and 2021–2023. The investigation on T. dumosa forest communities across their entire distribution range in China, totaling 114 survey locations were selected and 178 sample plots were established. We recorded species composition, quantitative characteristics, habitat information, and other relevant details of the communities. Through quantitative analyses, the main results of the study were as follows: (1) In 178 sample plots of T. dumosa Forest Alliance (simply called T. dumosa forests), a total of 403 vascular plant species were recorded. (2) T. dumosa forests were rich in community types, being classified into 11 association groups and 34 associations. (3) The forests’ vertical stratification was obvious. In the arborous layer there were mainly T. domosa and species of Quercus, Abies, Lithocarpus, Picea, Acer and Rhododendron. (4) T. dumosa’s regeneration was active. This study surely provides solid scientific data for a better understanding of the role of T. dumosa forests in the coniferous forest zone of China.