This study reports the first complete mitochondrial genome assembly of Hippophae salicifolia, an ecologically and economically important plant endemic to the Himalayas. The 475,105 bp genome has a 44.80% GC content and an overall AT bias, comprising 74 genes (37 protein-coding, 31 tRNA, three rRNA, and three pseudogenes). We identified extensive repetitive elements, including 188 SSRs, 20 tandem repeats, and 455 dispersed repeats, and explored their potential roles in genome evolution. Codon usage analysis showed a bias for codons ending in A or U, while RNA editing analysis revealed 415 sites that mostly convert hydrophilic to hydrophobic amino acids. Phylogenetic and collinearity analyses clarified evolutionary relationships within Hippophae and uncovered genome rearrangements. In addition, extensive gene transfer was detected between the mitochondrial and chloroplast genomes. Ka/Ks and nucleotide diversity analyses indicate that most genes are under purifying selection, with some possibly undergoing positive selection. Overall, these findings enhance our understanding of the structural and evolutionary features of the H. salicifolia mitochondrial genome and provide valuable insights for the genetic improvement and conservation of Hippophae species.

Paeonia ludlowii, a critically endangered species endemic to Tibet, China, possesses significant ornamental, culinary, and medicinal value. However, its mitochondrial genome remains understudied, limiting insights into its evolutionary mechanisms and constraining conservation genetics applications and molecular breeding programs. We present the first complete assembly and comprehensive analysis of the P. ludlowii mitochondrial genome. Most remarkably, we discovered that the P. ludlowii mitogenome exhibits an atypical dual-circular structure, representing the first documented occurrence of this architectural feature within the genus Paeonia. The assembled genome spans 314,371 bp and encodes 42 tRNA genes, 3 rRNA genes, and 31 protein-coding genes, with a pronounced adenine–thymine bias. This multipartite genome structure is characterized by abundant repetitive elements (112 functionally annotated SSRs, 33 tandem repeats, and 945 dispersed repeats), which potentially drive genome rearrangements and facilitate adaptive evolution. Analyses of codon usage bias and nucleotide diversity revealed highly conserved gene expression regulation with limited variability. Phylogenetic reconstruction confirms that P. ludlowii, P. suffruticosa, and P. lactiflora form a monophyletic clade, reflecting close evolutionary relationships, while extensive syntenic collinearity with other Paeonia species underscores mitochondrial genome conservation at the genus level. Extensive inter-organellar gene transfer events, particularly from chloroplast to mitochondrion, suggest that such DNA exchanges enhance genetic diversity and promote environmental adaptation. The discovery of the dual-circular architecture provides novel insights into plant mitochondrial genome evolution and structural plasticity. This study elucidates the unique structural characteristics of the P. ludlowii mitochondrial genome and establishes a crucial genetic foundation for developing targeted conservation strategies and facilitating molecular-assisted breeding programs for this endangered species.

As a climate‐sensitive region on a global scale, how environmental gradients on the Tibetan Plateau influence species diversity and community structure is an important scientific issue for understanding community assembly mechanisms in alpine ecosystems. This study focused on Betula platyphylla forests in the Nyang River Basin in the southeastern Tibetan Plateau (elevation 2990–4100 m), where a total of 16 plots (48 quadrats of 10 × 10 m) were established, field surveys were conducted, and hierarchical cluster analysis, canonical correspondence analysis (CCA), regression analysis, and Pearson correlation analysis were applied. The aims were to (1) explore the response patterns of woody plant diversity in B. platyphylla forests along the elevational gradient; and (2) evaluate the effects of key environmental factors, including elevation and soil properties, on the community distribution patterns of B. platyphylla forests. The results showed that a total of 71 woody plant species were recorded, belonging to 22 families and 40 genera, mainly represented by Rosaceae, Ericaceae, and Caprifoliaceae. It can be classified into four associations (Ass): B. platyphylla + Rhododendron bulu , B. platyphylla + Dasiphora fruticosa , Quercus aquifolioides + Lonicera tangutica , and B. platyphylla + Rhododendron triflorum . With increasing elevation, the species Margalef richness index ( M ), Shannon‐Wiener diversity index ( H ), Patrick richness index ( Pa ), and Simpson diversity index ( D ) showed a significant decline ( p < 0.05), while the Simpson dominance index ( C ) increased significantly ( p < 0.05). The Pielou evenness index ( J ) did not significantly respond to elevational gradients ( p > 0.05). CCA showed that environmental factors jointly explained 37.80% of the variation in community composition, among which elevation (Elev), soil alkali‐hydrolyzable nitrogen (AN), organic matter (OM), and available phosphorus (AP) were the main environmental factors affecting the woody plant community composition of B. platyphylla forests ( p < 0.05). This study provides key baseline data on plant diversity of B. platyphylla forests in this region and offers a scientific basis for the conservation and management of alpine forest ecosystems under climate change.

Niche and interspecific association are important components of community ecology and are of great significance for revealing the mechanisms of community assembly and its stability. In this study, the woody plant communities of Betula platyphylla Sukaczev forests in the Niyang River Basin of southeastern Qinghai–Tibet Plateau were taken as the research object. The niche, interspecific association, and community stability of dominant tree species in B. platyphylla forests were analyzed using the Levins index (B_L), Shannon index (B_S), Pianka index (O_ik), Schoener index (C_ik), variance ratio (VR), chi-square test, association coefficient (AC), Spearman rank correlation, and M. Godron stability methods. The results showed that a total of 71 woody plant species were recorded across 48 plots, mainly belonging to Rosaceae, Ericaceae, and Caprifoliaceae. B. platyphylla, Quercus aquifolioides Rehder & E. H. Wilson, Sorbus rehderiana Koehne, and Berberis gyalaica Ahrendt had relatively large niche breadths, indicating strong resource utilization ability and a wide range of spatial adaptation. They were the main constructive species and dominant species of B. platyphylla forest communities in this basin. The overall niche overlap of woody plant communities was relatively low, indicating relatively obvious differentiation in resource utilization among different species. Interspecific association analysis showed that the dominant species in the tree layer exhibited an overall significantly positive association, whereas those in the shrub layer exhibited an overall non-significantly positive association. The associations between species pairs were mainly non-significant, and the overall interspecific association was weak. Most species showed a relatively independent distribution pattern, reflecting weak interspecific competition within the community. Community stability analysis showed that the Euclidean distance between the tree layer and the theoretical stability point (20, 80) was 20.17, whereas that of the shrub layer was 27.98, indicating that the tree layer was more stable than the shrub layer. Overall, the community may not yet have reached a fully stable state. The results provide important references for biodiversity conservation, vegetation restoration, and sustainable forest management in alpine canyon ecosystems. Future studies should incorporate environmental factors such as soil properties and hydrothermal conditions to further reveal the ecological mechanisms driving community succession and stability.