Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations. In this study, we used double digest restriction-site-associated DNA sequencing (ddRAD) technology to assess the genetic diversity, genetic structure and demographic history of the three extant populations of R. meddianum. Analysis of SNPs indicated that R. meddianum populations have a high genetic diversity (π = 0.0772 ± 0.0024, H_E = 0.0742 ± 0.002). Both F_ST values (0.1582–0.2388) and AMOVA showed a moderate genetic differentiation among the R. meddianum populations. Meanwhile, STRUCTURE, PCoA and NJ trees indicated that the R. meddianum samples were clustered into three distinct genetic groups. Using the stairway plot, we found that R. meddianum underwent a population bottleneck about 70,000 years ago. Furthermore, demographic models of R. meddianum and its relative, Rhododendron cyanocarpum, revealed that these species diverged about 3.05 (2.21–5.03) million years ago. This divergence may have been caused by environmental changes that occurred after the late Pliocene, e.g., the Asian winter monsoon intensified, leading to a drier climate. Based on these findings, we recommend that R. meddianum be conserved through in situ, ex situ approaches and that its seeds be collected for germplasm.

Magnolia sinica (Magnoliaceae) is a highly threatened tree endemic to southeast Yunnan, China. In this study, we generated for the first time a high-quality chromosome-scale genome sequence from M. sinica, by combining Illumina and ONT data with Hi-C scaffolding methods. The final assembled genome size of M. sinica was 1.84 Gb, with a contig N50 of ca. 45 Mb and scaffold N50 of 92 Mb. Identified repeats constituted approximately 57% of the genome, and 43,473 protein-coding genes were predicted. Phylogenetic analysis shows that the magnolias form a sister clade with the eudicots and the order Ceratophyllales, while the monocots are sister to the other core angiosperms. In our study, a total of 21 individuals from the 5 remnant populations of M. sinica, as well as 22 specimens belonging to 8 related Magnoliaceae species, were resequenced. The results showed that M. sinica had higher genetic diversity (θw = 0.01126 and θπ = 0.01158) than other related species in the Magnoliaceae. However, population structure analysis suggested that the genetic differentiation among the 5 M. sinica populations was very low. Analyses of the demographic history of the species using different models consistently revealed that 2 bottleneck events occurred. The contemporary effective population size of M. sinica was estimated to be 10.9. The different patterns of genetic loads (inbreeding and numbers of deleterious mutations) suggested constructive strategies for the conservation of these 5 different populations of M. sinica. Overall, this high-quality genome will be a valuable genomic resource for conservation of M. sinica.

Anthropogenic global warming, nitrogen addition, and overgrazing alter plant communities and threaten plant biodiversity, potentially impacting community productivity, especially in sensitive mountain grassland ecosystems. However, it still remains unknown whether the relationship between plant biodiversity and community productivity varies across different anthropogenic influences, and especially how changes in multiple biodiversity facets drive these impacts on productivity. Here, we measured different facets of biodiversity including functional and phylogenetic richness and evenness in mountain grasslands along an environmental gradient of elevation in Yulong Mountain, Yunnan, China. We combined biodiversity metrics in a series of linear mixed‐effect models to determine the most parsimonious predictors for productivity, which was estimated by aboveground biomass in community. We examined how biodiversity–productivity relationships were affected by experimental warming, nitrogen addition, and livestock‐grazing. Species richness, phylogenetic diversity, and single functional traits (leaf nitrogen content, mg/g) represented the most parsimonious combination in these scenarios, supporting a consensus that single‐biodiversity metrics alone cannot fully explain ecosystem function. The biodiversity–productivity relationships were positive and strong, but the effects of treatment on biodiversity–productivity relationship were negligible. Our findings indicate that the strong biodiversity–productivity relationships are consistent in various anthropogenic drivers of environmental change.

Rhododendron kuomeianum Y.H. Chang, J. Nielsen & Y.P. Ma, a new species of Rhododendron (Ericaceae) within subsect. Maddenia in sect. Rhododendron from Yiliang County, NE Yunnan, China, is described and illustrated. The new species is similar to R. valentinianum, but it can be easily distinguished by its sparse scales on the abaxial surface of the leaf blade, fewer flowers per inflorescence and white corolla with pale red margins. There are also differences in the widths of calyx lobes, leaf blade shape and indumentum characteristics of the petiole between the new species and Rhododendron linearilobum. We confirmed that R. kuomeianum is a new species closely related to R. valentinianum and R. changii with phylogenomic studies of 10 species within this subsection based on restriction site-associated DNA sequencing (RAD-seq) data. These phylogenomic analyses also clarified additional taxonomic problems in this subsection previously raised by morphological analysis. Our findings make a strong case for using next-generation sequencing to explore phylogenetic relationships and identify new species, especially in plants groups with complicated taxonomic problems.

Climate change is a major factor affecting biodiversity and species distribution, particularly of montane species. Species may respond to climate change by shifting their range to higher elevations. The southeastern Qinghai‐Tibetan Plateau (QTP) and the Hengduan Mountains are considered as global biodiversity hotspots. However, information on the response of maple species to climate change in these regions was limited. Therefore, we selected two maple species that occur there and assessed changes in their habitat suitability under past, present and future climate scenarios in Biomod2. The results showed that temperature seasonality (bio4) was the most critical factor influencing their potential distributions. The distribution of potentially suitable habitat for Acer caesium and Acer stachyophyllum was predicted to be larger during the LGM compared to the present. Under the current climate scenario, the largest areas of potentially suitable habitat for these species were mainly located in southeastern Tibet, the Hengduan Mountains in northwestern Yunnan and western Sichuan, the Qinling‐Daba Mountains in southern Gansu and the Wumeng‐Daliang Mountains in northeastern Yunnan, western Guizhou and southeastern Sichuan. Under future climate change scenarios, the predicted loss of suitable habitat areas for these two species ranged from 13.78% to 45.71% and the increase ranged from 18.88% to 57.98%, with an overall increasing trend. The suitable habitat areas were predicted to shift towards the eastern parts of the QTP under both the pessimistic and optimistic future climate change scenarios in the 2050s and the 2070s, which became evident as global warming intensified, particularly in the eastern QTP and the Hengduan Mountains. Our results highlight the possibility that the diverse topography along altitudinal gradients in the QTP and the Hengduan Mountains may potentially mitigate the range contraction of mountain plants in response to climate warming. These findings provide a basis for planning conservation areas, planting and species conservation in the mountainous areas of southern China under the anticipated global warming.