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.

Lianas play a crucial role in forest species diversity, biomass, nutrient cycling, and vegetation restoration. To date, numerous studies on the stoichiometric characteristics of liana leaves have predominantly focused on temperate, subtropical, and tropical forests. However, there remains a lack of comprehensive understanding regarding the nutrient concentrations and their stoichiometric characteristics in lianas growing in rocky desertification habitats. In the present study, we investigated six leaf nutrient concentrations and three stoichiometric ratios across 20 liana species in various subtropical rocky desertification habitats. The results indicated that lianas in habitats with severe rocky desertification exhibited significantly higher potassium concentrations in their leaves compared to those in habitats with moderate rocky desertification. Within habitats characterized by moderate rocky desertification, there were notable positive correlations observed between the nitrogen, phosphorus, and potassium concentrations in liana leaves. However, in habitats with severe rocky desertification, phosphorus demonstrated significant positive correlations with both magnesium and potassium. Principal component analysis further revealed that lianas in severely desertified habitats tended to possess higher concentrations of leaf potassium and calcium, whereas those in moderately desertified habitats exhibited an opposite trend. The findings of this research provide crucial theoretical insights that can guide vegetation restoration efforts in different rocky desertification regions.

Soil microbiomes play pivotal roles in mediating plant diversity maintenance by regulating multifunctional ecosystem services during plant development. However, how different stand age of plants influence soil microbial communities in various soil compartments remains poorly understood. Through Illumina-based 16S rRNA and ITS amplicon sequencing, we systematically investigated the successional trajectories of soil microbiome in Pinus armandii plantations spanning various developmental phases. Key findings revealed that stand age exerted a stronger influence on microbial restructuring than soil compartment, significantly altering community composition in both soil types. Alpha diversity (Shannon and Chao1 indices) exhibited a U-shaped trajectory with stand age, except for fungal Chao1 in bulk soil. While dominant bacterial and fungal phyla remained relatively stable, community composition displayed significant stage-dependent variations. Co-occurrence network analysis demonstrated lower fungal network complexity compared to bacterial networks, with rhizosphere soils harboring more intricate interactions compared to bulk soils. Community assembly mechanisms diverged: deterministic processes dominated bacterial assembly, whereas stochasticity governed fungal communities. Soil properties exerted significant influences on microbial composition and diversity: bacterial composition correlated strongly with pH and stoichiometric ratios (C/N, C/P, N/P), while fungal composition showed stronger associations with TN, TP, and AN. Our results demonstrate that P. armandii plantations maintain core phylum-level microbial populations while developing stage-specific diversity patterns. Crucially, bacteria and fungi exhibit divergent responses to stand development, highlighting their divergent ecological strategies in adapting to nutrient-limited karst ecosystems.

Quercus rehderiana Hand.-Mazz. is a genus of Quercus in the Fagaceae family, which widely distributed in Guizhou Province in Southwest China. It has important ecological significance in soil and water conservation, species diversity maintenance, and climate regulation. To date, the researches on stoichiometric characteristics of Quercus mainly focus on leaves, and few studies on roots. However, the difference of leaf and root stoichiometric characteristics of Quercus between in forests with rocky and non-rocky desertification are still unclear. In this study, we compared leaf (15 individuals) and root (9 individuals) carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) concentrations and their stoichiometric ratios in five 20 x 20 m quadrants of forests with rocky and non-rocky desertification. The aim was to find their resource strategies of adaptation to nutrient deficient soil environments in forests with rocky desertification. Our results show that leaf P and K concentrations in forest with non-rocky desertification were significantly higher than those in forest with rocky desertification, Ca and Mg concentrations were opposite. Root N, Ca and Mg concentrations in forest with rocky desertification were significantly higher than that in forest with non-rocky desertification, P and K concentrations were opposite. The N:P of leaves were greater than the threshold value of phosphorus (16) both in forests with rock and non-rocky desertification. Leaf P concentration was positively correlated with N concentration in forest with non-rocky desertification. Root N concentration was positively correlated with P concentration in forest with non-rocky desertification. C concentration of leaves and roots in forest with rocky desertification was negatively correlated with Ca concentration. In conclusion, leaf and root showed an obvious difference in nutrients and stoichiometric characteristics between in forests with rocky and non-rocky desertification. The growth of Q. rehderiana both in forest with rocky and non-rocky desertification was mainly limited by P. The trade-offs and synergies of nutrient absorption and utilization by different plant organs are both similar and different in different forests. Therefore, proper addition of N and P nutrients in plant growth period can promote plant growth and development, and help to improve the stability of forest ecosystem. The research results have practical significance for the vegetation restoration and protection in forests with rocky desertification.

Phosphorus (P) is a pivotal element in plant energy metabolism and growth, and P limitation is widespread among plants in nature. However, our understanding of how epiphytes allocate P and adapt to P-deficient environments remains limited. We selected an obligate epiphyte Pyrrosia sheareri from a subtropical forest as our research subject. We compared its carbon (C)–nitrogen (N)–P ecological stoichiometry, P fractions, and morphological and physiological traits under the two habitats (trunk-epiphytic and rock-epiphytic). We also constructed a plant trait network method (PTN) that includes 62 traits to explore the co-variation characteristics of plant traits across the whole plant and identify the hub traits. We found that the following: (1) Habitat type significantly affects plant P concentration, with trunk-epiphytic plants having higher P concentration than rock-epiphytic plants. Pyrrosia sheareri may be more strongly limited by P according to the results of C-N-P ecological stoichiometry. (2) Epiphytic habitats significantly affect plant P fractions but do not influence the relative allocation of P fractions. (3) Compared with rock-epiphytic plants, trunk-epiphytic plants adopt a root resource-acquisition strategy rather than relying on leaves. (4) P-related indicators link ecological stoichiometry with morphological and physiological traits and are hub traits in PTN. Overall, P. plays a key functional role in the environmental acclimatization of Pyrrosia sheareri, highlighting the morphological and physiological adaptability of epiphytes to various habitats in terms of P availability, allocation, and storage.