Southwest China is distributed with the largest area of limestone and dolomite karst landscapes in the world, and its ecological environment is very fragile; the problem of rock desertification is particularly prominent. Karst lithological differences make habitats and soil heterogeneity more complex, and vegetation has developed certain morphological and physiological structural characteristics to adapt to these special environments, which will most likely lead to differentiation in vegetation functional characteristics, such as seed size, wood density, life type and flowering time, thus affecting the number and growth of seedlings and young trees and the future succession potential of forest stands in karst-vegetation restoration. Therefore, it is important to understand the differences in species composition and the functional characteristics of dolomite and limestone karst forests. Over a 2-year period, we investigated a total of 3170 individuals from 123 species and analyzed the relationship between the species compositions and the functional characteristics of two karst-forest areas with different lithology (i.e., limestone and dolomite karst). It was found that the average number of species with medium-diameter seeds and medium wood density in dolomite plots was obviously greater than the average number of species in limestone plots, but this reached no significant difference. However, with the gradual restoration of each forest, the height and carbon sequestration capacity of the trees began to diverge, with the relative abundance of species with tall trees and high wood density being significantly higher in limestone plots than in dolomite plots. The species richness of evergreen trees was significantly higher in the limestone plots than in the dolomite plots. There was no significant difference in the relative species richness of flowering plants in the two karst-forest areas during spring–summer and winter–spring seasons; however, the species richness of flowering plants in the limestone karst forests was significantly higher than that of flowering plants in the dolomite karst forests during summer and autumn seasons. These significant traits were very closely related to the species richness of the understory plants. Further insight into the temporal aspects of karst-forest succession is needed to grasp how functional traits affect the restorations of different lithological karst forests to their primary states.

To explore environmental differentiation in the stoichiometric characteristics of carbon (C), nitrogen (N), phosphorus (P), potassium (K), and their ratios among tree species organs in different lithological karst regions of Guizhou, six common species were selected from the limestone karst area of Liping and the dolomite karst area of Shibing. The analysis focused on the differences in the contents of C, N, P, and K, as well as the ratios of C/N, C/P, C/K, and N/P, and the correlations among these elements in branches, leaves, and roots, with the aim of investigating the allocation distribution patterns of nutrient elements among organs in tree species under different lithological karst conditions. The results showed the following: In both dolomite and limestone karst regions, the tree species exhibited a distinct characteristic: their leaves exhibited high C levels, but relatively low N and P levels. Tree species in both karst regions showed high C/N, C/P, and C/K ratios, indicative of rapid C assimilation rates and efficient utilization of N, P, and K. Plant growth in the dolomite region was N-limited, while plant growth in the limestone region was P-limited. However, plant growth in neither region was K-limited. The nutrient characteristics and adaptation strategies of plants in dolomite and limestone karst regions were the result of multiple factors, such as lithology, plant organs, and interactions among elements. In conclusion, considering the differences in lithology during vegetation restoration and management in karst regions, targeted application of nitrogen or phosphorus fertilizers is expected to promote plant growth and further enhance the carbon sequestration capacity of both karst plants and soils.

While persistent calyces exhibit considerable functional diversity, this has not been fully substantiated by experiments, especially concerning their thermoregulatory function. This study investigates the thermoregulatory function of persistent calyx in winter-flowering Brandisia hancei. Changes in calyx dimensions throughout the flowering-to-fruiting developmental stages were measured. Differences between floral and ambient temperatures were measured when only calyxes were retained. Additionally, differences in floral temperature between calyx-removed treatments and intact controls were also measured. All measurements were taken at three developmental stages: pre-anthesis, anthesis, and post-anthesis. Furthermore, seed production after calyx manipulation was examined at both anthesis and post-anthesis stages. The calyx exhibits continuous size enlargement from flowering to fruiting stages. After either artificial corolla removal or natural corolla abscission, the calyx independently maintains thermoregulatory capacity, sustaining floral temperatures significantly above ambient levels. Consequently, calyx removal resulted in markedly diminished floral temperature at both pre- and post-anthesis stages. In line with the thermoregulation results, progressive removal of the calyx showed a strong negative correlation with seed production. In contrast, removal of only the calyx edge generally maintained seed production at a level comparable to that of the intact control. Collectively, our findings demonstrate that the persistent calyx plays a critical role in elevating reproductive temperature under winter conditions, enhancing reproductive success in B. hancei through the maintenance of a favorable thermal conditions for reproduction. This study provides direct evidence that plant reproductive structures can markedly adapt to winter low-temperature stress through such a thermoregulatory mechanism.

Acer truncatum is a significant woody oil-bearing tree species known for its ability to synthesize various unsaturated fatty acids. This study systematically analyzes the lipid metabolic pathways and the associated transcript abundance changes involved in the biosynthesis and accumulation of seed oil in A. truncatum. By integrating lipidomics and transcriptomics analyses across different developmental stages of A. truncatum seeds, we thoroughly investigate the dynamic characteristics of oil metabolism. The results show that triacylglycerols (TAGs) become the dominating lipid class throughout seed development and that their amount increases greatly as the seeds mature, whereas diacylglycerols (DAGs) show a significantly decreased relative abundance. Numerous differentially expressed genes (DEGs) linked to lipid biosynthesis were identified by transcriptome analysis, including AcACCase, AcKAS, AcKCS, AcGPAT, AcDGAT, and AcOLE. The expression patterns of DGAT- and KCS-encoding genes differ noticeably between immature and mature seeds. Integrated lipidomics and transcriptomics analyses suggest stage-associated lipid metabolic changes during seed development of A. truncatum. This study also highlights candidate genes and metabolic pathways with TAG accumulation. These findings improve our understanding of seed oil metabolism in A. truncatum by linking AcDGAT-related TAG assembly and AcKCS-driven very-long-chain fatty acid elongation to the developmental regulation of the Kennedy pathway (TAG biosynthesis) and fatty acid elongation (VLCFA/NA-related), providing essential molecular insights for the genetic improvement of oil yield and fatty acid quality in this species.