Climate change is an important driver of biodiversity patterns and species distributions, understanding how organisms respond to climate change will shed light on the conservation of endangered species. In this study, we modeled the distributional dynamics of a critically endangered montane shrub Lonicera oblata in response to climate change under different periods by building a comprehensive habitat suitability model considering the effects of soil and vegetation conditions. Our results indicated that the current suitable habitats for L. oblata are located scarcely in North China. Historical modeling indicated that L. oblata achieved its maximum potential distribution in the last interglacial period which covered southwest China, while its distribution area decreased for almost 50% during the last glacial maximum. It further contracted during the middle Holocene to a distribution resembling the current pattern. Future modeling showed that the suitable habitats of L. oblata contracted dramatically, and populations were fragmentedly distributed in these areas. As a whole, the distribution of L. oblata showed significant migration northward in latitude but no altitudinal shift. Several mountains in North China may provide future stable climatic areas for L. oblata, particularly, the intersections between the Taihang and Yan mountains. Our study strongly suggested that the endangered montane shrub L. oblata are sensitive to climate change, and the results provide new insights into the conservation of it and other endangered species.

Background: Plants in cliff habitats may evolve specific reproductive strategies to cope with harsh environments, and unraveling these reproductive characteristics can improve our understanding of survival strategies and lithophyte evolution. This understanding is especially important for efforts to protect rare and endemic plants. Here, we investigated the reproductive biology of Lonicera oblata, an endangered lithophytic shrub that is scattered in highly fragmented and isolated cliff habitats of the Taihang and Yan mountains in North China. Results: Flowers of L. oblata are herkogamous and protandrous, characteristics that can prevent autogamy at the single-flower level, and insects are necessary for pollination. The outcrossing index, pollen/ovule ratio, and the results of hand pollination were measured and all revealed a mixed mating system for L. oblata, that combines cross-fertilization and partial self-fertilization. The floral traits of L. oblata of zygomorphic and brightly yellowish corolla, heavy fragrance, and rich nectar, suggest an entomophilous pollination system. Sweat bees were observed as the most effective pollinators but their visiting frequencies were not high. Pollen limitation may limit the reproductive success of L. oblata. Conclusions: We determined the reproductive characteristics of L. oblata, a critically endangered species endemic to cliffs in North China, providing insight into its endangerment and suggesting conservation strategies. L. oblata has highly pollinator-dependent self-fertilization as part of a mixed mating system. Floral features such as low-flowering synchrony, asynchronous anthers dehiscence, and high duration of stigma receptivity, improve pollination efficiency in the case of low pollinator service. Our work provides reference information to understand the survival strategies and conservation of L. oblata and other lithophytes.

High genetic diversity and low differentiation present challenges in taxonomy and systematics of Salix. Chloroplast (cp) genome sequencing is efficient for providing new genomic information and elucidating phylogenetic relationships. Salix spathulifolia Seemen, S. cupularis Rehder, and S. annulifera C.Marquand & Airy Shaw are three shrubby willows spread in high-altitude regions in western China. In this study, the integrated circular cp genomes were sequenced and analyzed, and a phylogeny of Salix was constructed on the basis of the cp genomes. The results of chloroplast assembly and annotation information were used to characterize genome feature and interspecific variation. The phylogenetic position of the three willows was evaluated using phylogenetic analysis. Full-length cp genomes were 155,566–155,680 bp with a typical double-stranded circular quadripartite structure, containing one large single-copy region (LSC, 84,431–4552 bp), one small single-copy region (SSC: 16,206–16,221 bp), and two inverted repeats (IR: 27,453–27,461 bp). The cp genomes encoded 130 genes, including 8 rRNA genes, 37 tRNA genes, and 85 protein-coding genes. The guanine-cytosine (GC) content of the overall genome was 36.7%. Comparison among the three willows’ cp genomes revealed high similarity. Phylogenetic analysis indicated that S. spathulifolia was a basal taxon of clade I, while S. annulifera formed a monophyletic group with S. rorida Laksch.; S. cupularis was sister to S. suchowensis W.C. Cheng and S. psammophila Z. Wang & Chang Y. Yang. The complete chloroplast genomes of the three willows provides an additional sequence-based resource for studying the phylogeny and evolutionary history of Salicaceae.

The spatial heterogeneity of soil nutrients is crucial for the water bird and whole floodplain wetland ecosystem in large lakes, and it is influenced by the dramatic water level changes and sedimentation progress in West Dongting Lake (WDL). Soil samples were collected at various soil depths along the Yuan River and Li River that feed into WDL. The concentrations of soil total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), and soil grain size were tested. The stoichiometric ratios of C, N, P, and the mean value of soil grain size (Mz) were calculated. The differences of soil TOC, TN, TP and the stoichiometric ratio at different sites and soil depths were compared. Linear regression was used to explore the relationships of Mz and nutrient concentrations, and relationships between TOC, TN, and TP. Redundancy analysis was used to explore the relationship between soil nutrients, heavy metal concentrations, and plant community diversity. The results showed that the distributions of soil TOC, TN, and TP concentrations differed across regions in west Dongting Lake along the Yuan and Li Rivers. Total organic carbon concentration differed at different sedimentation depths. Soil grain size showed negative effect with soil TOC, TN, and TP concentrations in this region. Plant community diversity correlated positively with soil TOC and negatively with Hg. West Dongting Lake was N limited despite the high wet deposition of N. It could potentially be attributed to the insufficient presence of aerobic environments for microbes during intermittent flooding of the floodplain, coupled with feeble mineralization. This study can provide valuable insights for the conservation of water bird habitats and wetland ecosystems.

Primula maershanensis J.L.Gu & Z.K.Wu, a new species of Primulaceae from Sichuan, China, is described and illustrated. Morphological evidence supports the placement of P. maershanensis within Primula sect. Auganthus , a section characterized by leaves that are shallowly to deeply lobed and covered with hairs and by a distinctively broad calyx with a flattened base. The new species is distinguished from other species in this section by its short rhizome and nearly fleshy roots; subpurple petioles and scapes; leaf blade suborbicular, wider than long, margin palmately 5–9-lobed to the middle of the blade; and a bright yellow corolla associated with long-homostylous flowers. Information on the distribution, morphological comparisons with closely related species, and the conservation status of the new species is also provided, along with a key to the known species of Primula sect. Auganthus .

Climate change poses a significant threat to biodiversity, highlighting the urgent need to understand species' adaptive potential. Using the sky island limestone-endemic shrub Lonicera oblata in North China as a model, we integrated genomic, transcriptomic, and metabolomic analyses to investigate its evolutionary trajectory. The assembled genome is 786.92 Mb in size, and it has the highest proportion of repetitive sequences (66.47%) in Lonicera. Multiple expanded gene families were enriched in pathways related to stress response, including oxidoreductase activity, cell wall synthesis, and energy metabolism. The bHLH gene family exhibits both a significant expansion in the comparative genomic analysis and a convergent transcriptional activation under calcium stress, correlating with the metabolic reprogramming of organic acid synthesis and ion homeostasis. We detected low genetic diversity (π: 2.24e–3 to 2.80e–3), high differentiation (average fixation index: 0.16), drastic historical decline, and strong genetic load among populations. Notably, the northeasternmost and most recently diverged population (Jiankou) exhibited extreme inbreeding but the lowest genetic load, suggesting that genetic purging enhances small population survival. The genotype-environment association analysis identified 1,286 core SNPs potentially correlated with local adaptation. Genomic offset projections predicted high maladaptation risk under future climates, especially in eastern and southern populations. This study provides essential insights into the mechanisms of local adaptation, genomic vulnerability, and climate resilience of threatened sky island species, and offers guidance for targeted conservation strategies.