Investigation on the Resource Status and Vegetation Community of Cephalostachyum mannii, a Plant with Extremely Small Population

Cephalostachyum mannii is a wild plant with an extremely small population, urgently requiring enhanced conservation efforts. However, current knowledge about its resource status and community conditions is limited, severely hindering the formulation and implementation of conservation plans. Through systematic field investigations and literature review, this study, for the first time, clarified the resource status and community conditions of this species, elucidated its geographical distribution and habitat characteristics, and proposed specific conservation and management recommendations. The results are as follows: (1) C. mannii is exclusively distributed in China within a narrow area along both banks of the Dulong River in Maku Village and Bapo Village, Dulongjiang Township, Gongshan County, northwest Yunnan, at elevations ranging from 1,241 to 1,480 meters. The wild population comprises 11 distribution points with 162 clumps and 9,909 stems, covering an area of 26.05 hectares. The wild distribution range is narrow, with a small number of existing populations and individual plants. The populations exhibit a "patchy" or discontinuous "island-like" distribution, with significant isolation among populations. (2) The habitats are located along riverbanks and on steep, abrupt, and precipitous slopes at the lower parts of hillsides, characterized by numerous cliffs. Among the 11 distribution points, only two are within protected areas, indicating a substantial conservation gap. The habitats are significantly impacted by human disturbances such as cultivation, road construction, and logging, leading to severe habitat fragmentation and a concerning survival status. (3) C. mannii serves as an associated tree species in the second arbor layer in most communities. These communities have a small distribution area. Occasionally, communities with C. mannii as the single dominant species are formed after the destruction of the upper vegetation layer. However, these communities contain a relatively large number of protected species and hold high scientific research and conservation value. (4) The vegetation where C. mannii occurs comprises three vegetation types, three vegetation subtypes, and six communities. The vertical structure of the communities is distinct, consisting of three layers: trees, shrubs, and herbs, with coverage rates ranging from 35-65%, 15-50%, and 30-75%, respectively. (5) The vegetation communities of C. mannii are species-rich. Within a 2,400 m sample plot, there are 104 vascular plant species belonging to 88 genera and 51 families. Eight families, including Lauraceae and Poaceae, are dominant, accounting for 42 species, representing 15.69% of the total families and 40.39% of the total species, indicating a rich species composition and prominent status of dominant families within the community. (6) Among the six sample plots surveyed, five have Simpson diversity indices and Pielou evenness indices above 0.9, and Shannon-Wiener diversity indices above 0.3, indicating that the communities are species-rich and exhibit relatively even species distribution.