Rocky desertification (RD), a natural and human-induced process of land degradation in karst areas, has become the primary ecological disaster and one of the obstacles to sustainable ecological development in southwest China. Nevertheless, the variation of soil physical and chemical properties, bacterial and fungal communities, and their relationships in RD forests remains limited. Therefore, soil samples were collected from forests under four degrees of RD (NRD, non-RD; LRD, light RD; MRD, moderate RD; and SRD, severe RD) and subjected to high-throughput sequencing of 16S rRNA and ITS1 genes. The results showed a significant reduction in bacterial richness and diversity, while fungal richness and diversity decreased markedly and then showed a balanced trend with the increase in RD degree, indicating that bacteria and fungi did not present the same dynamics in response to the process of RD. The bacterial communities were dominated by Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi, while the fungal communities were dominated by Basidiomycota, Ascomycota, and Mortierellomycota. The PCoA and NMDS demonstrated significant differences in microbial communities in study sites, among which the fungal communities in non-RD forest and LRD forest clustered together, suggesting that fungal communities were more stable than bacteria in RD forest. The db-RDA, Mantel test, and random forest model confirmed the important role of soil BD, pH, SOC, AN, and AP in driving microbial diversity and communities. The IndVal analysis suggested that Chloroflexi, Patescibacteria, Atheliales, and Cantharellales with high indicator values were identified as potential bio-indicators for RD forests. This study could not only improve our understanding of bacterial and fungal community dynamics across RD gradients, but also could provide useful information for the further use of microorganisms as indicators to reflect the environmental changes and ecosystem status during forest RD.

Quercus rehderiana Hand.-Mazz. belongs to Quercus sect. Heteroallenes’ of the Fagaceae family. It is widely distributed in forests with rocky and non-rocky desertification in Guizhou Province of Southwest China. However, our knowledge of the adaptation strategies of Quercus in forests with rocky desertification is surprisingly lacking. In this study, 16 leaf traits (morphological, anatomical, and chemical) of Quercus rehderiana were investigated in 15 individuals in five 20 × 20 m quadrants of forests with rocky and non-rocky desertification. The aim was to analyze their strategies of adaptation to arid and poor-soil environments in forests with rocky desertification. The results showed that Quercus rehderiana leaves in forests with rocky desertification had a greater leaf thickness, specific leaf area, abaxial epidermis thickness, and sponge mesophyll thickness but a lower leaf area than in forests with non-rocky desertification. Quercus rehderiana leaves in forests with rocky desertification had higher calcium and magnesium concentrations and a higher N:P ratio but lower potassium and phosphorus concentrations than in forests with non-rocky desertification. The results of principal component analysis showed that forests with rocky desertification tended to show resource-conserving strategies with thicker leaf tissue and a lower nutrient concentration, while forests with non-rocky desertification tended to show resource acquisition strategies with a greater leaf area and potassium concentration. In resource-poor environments, species that adopt conservative resource strategies are more likely to survive; therefore, we forecasted that more conservative, slow-growing Quercus rehderiana will be more stable over time.

Rosa roxburghii Tratt., a fruit crop known for its high Vitamin C content and other nutritional compounds, has not yet been studied for its auxin response factor (ARF) family members. ARFs are important proteins in auxin-mediated pathways, playing a vital role in plant physiological and biochemical processes such as plant development, and flower and fruit maturation. In the present study, we identified 14 ARF genes (designated as RrARFs) in R. roxburghii, which are distributed across seven chromosomes and grouped into four subfamilies. An analysis of cis-acting elements revealed that these genes might be involved in various biological processes, including plant development, flower development, light responses, cell cycle regulation, phytohormone responses, and responses to abiotic and biotic stresses. A gene expression analysis demonstrated differential expression of RrARF genes across different tissues and stages of fruit development, with four members showing higher expression during the fruit ripening stages. Furthermore, a coexpression analysis identified that RrARF5 was highly coexpressed with RrMDHAR1, a key enzyme involved in Vitamin C biosynthesis. Moreover, transactivation assays and transient overexpression experiments confirmed that RrARF5 activates the transcription of RrMDHAR1. The findings of this study suggest a potential role of the ARF gene family in Vitamin C accumulation in R. roxburghii and enhance our understanding of the diverse regulatory function of the ARF gene family in plants.

Assessing the functional traits and ecological stoichiometric characteristics of dominant species across different life forms within plant communities in karst environments and investigating the inherent connection between them can provide insights into how species adjust their functional attributes in response to habitat heterogeneity. This approach offers a more comprehensive understanding of ecosystem processes and functions in contrast to examination of the taxonomic diversity of species. This study examines the relationship between the functional characteristics of dominant species in plant communities of various life forms in karst environments, focusing on deciduous leaf–soil ecological stoichiometry. The investigation relies on community science surveys, as well as the determination and calculation of plant functional traits and ecological stoichiometries, in plant communities of various life forms in Guizhou (a province of China). The findings of our study revealed considerable variability in the functional trait characteristics of dominant species across different plant-community life forms. Specifically, strong positive correlations were observed among plant height (PLH), leaf area (LA), leaf dry matter content (LDMC), and specific leaf area (SLA) in the dominant species. Additionally, our results indicated no significant differences in leaf ecological stoichiometry among different life forms. However, we did observe significant differences and strong positive correlations between soil N:P, withered material C:N, and apomictic C:P. Furthermore, our study found that plant height (PLH), leaf area (LA), and specific leaf area (SLA) were particularly sensitive to the ecological stoichiometry of soil and apomixis. The results of our study suggest that the functional traits of diverse plant-community life forms in karst regions are capable of adapting to environmental changes through various expressions and survival strategies. The development of various plant-community life forms in karst areas is particularly vulnerable to phosphorus limitation, and the potential for litter decomposition and soil nutrient mineralization is comparatively weaker. The functional traits of various plant-community life forms in karst regions exhibit greater sensitivity to both the soil’s C:N ratio and the C:N ratio of apomictic material. Habitat variations may influence the ecological stoichiometric characteristics of the plant leaf–apomictic soil continuum.

Exploring the changes in plant leaf functional traits in response to altitude across various altitudinal gradients of climax communities in karst regions can elucidate the characteristics of survival strategy adaptations among plant communities. This understanding may also reveal the growth dynamics and driving factors of climax communities in unique habitats. In this study, we examined nine climax communities located in the karst region of Southwest China, categorizing them into three distinct altitude gradients: low-, middle-, and high-altitude communities. By integrating species characteristics and community structure, we analyzed the patterns of change in leaf functional traits among plant communities at different altitudinal gradients and the relationships between these functional traits and environmental factors across the varying altitudes. The results indicated the following: (1) There was a significant difference in the specific leaf area (SLA) of the community as altitude increased, with a gradual decrease observed. The traits exhibiting higher coefficients of variation (CVs) in the leaves of the karst vertex community included the leaf carbon-to-nitrogen ratio (LCN), leaf area (LA), and leaf dry matter content (LDMC). Additionally, the environmental factors with higher CVs included soil organic carbon (SOC), soil phosphorus content (SPC), and the soil carbon-to-phosphorus ratio (SCP). (2) Soil organic carbon content (SOC), total nitrogen content (SNC), carbon-to-phosphorus ratio (SCP), and nitrogen-to-phosphorus ratio (SNP) demonstrated significant differences with increasing altitude. (3) The primary environmental factors influencing plant communities in karst areas included soil nitrogen content (SNC), mean annual temperature (NJW), soil organic carbon content (SOC), soil phosphorus content (SPC), soil water content (SWC), and mean annual precipitation (NJS). Our results indicated that the variation in leaf functional traits with altitude in karst climax communities was inconsistent. Among these traits, the specific leaf area (SLA) showed the most significant variation, and karst climax communities appeared to adapt to environmental changes by regulating traits such as leaf area (LA), leaf dry matter content (LDMC), and leaf carbon-to-nitrogen ratio (LCN). Soil organic carbon (SOC) and soil phosphorus content (SPC) are key factors contributing to habitat heterogeneity in the karst region. The karst climax communities are influenced by both soil and climatic factors along the altitudinal gradient. As altitude increases, these communities tend to adopt a life strategy. Furthermore, high-altitude terminal communities in karst areas are more susceptible to environmental filtering, while low-altitude areas are more affected by limitations in similarity.