Bacteria play an important role as decomposers in karst ecosystems, which can be associated with karst soil and plants, promoting the cycling of nutrients between plants and soil. To reveal the diversity and structure of soil bacterial communities in some karst land-use types after the Grain for Green pattern, soil samples were collected from different land-use types (crops, grasses, and plantations) for analysis. Changes in the structure and assembly of karst soil bacteria were examined using 16S rRNA Illumina sequencing and soil chemical properties. We found that 18 years after the Grain for Green program, the soil chemical properties of available nitrogen (AN), total phosphorus (TP), total nitrogen (TN), and soil organic matter (SOM) of grassland were significantly different from those of farmland. The soil chemical properties in plantations were also significantly lower than those in farmlands. Different land-use types did not significantly affect the soil bacterial community structure. Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria were the dominant phyla in all the plots. The relative abundance of Proteobacteria was higher in grasslands and plantations than in farmlands, whereas that of Actinobacteria was lower in grasslands. Furthermore, no significant correlations were observed between the soil chemical factors and soil bacterial groups at the genus level. The null model analysis indicated that dispersal limitations in stochastic processes predominated for the different land-use systems. Combined with previous analyses of the factors driving bacterial core species diversity in karst soils, we speculated that stochastic processes play a more important role in the construction of core bacterial species in restored karst soils at the plot scale.

Little is known about the competition between and niche differentiation of water and nutrients between angiosperm and gymnosperm tree species under prolonged drought stress, especially in fragile environments. We imposed 21 d drought and competition treatments on Broussonetia papyrifera and Platycladus orientalis and measured water, N, and P contents, the isotopic composition of N and C, the activity of P assimilation enzymes, and stomatal conductance under solo planting and mixed planting to characterize resource diversity and competition in response to treatments. The N content, δ¹³C, δ¹⁵N, phosphomonoesterase, phosphodiesterase, g_s, and foliage water content were significantly affected by the soil water content. The δ¹⁵N content in young leaves showed that N competition between these two plants could be alleviated through niche differentiation, but the changes in the PDE: PME ratio for these two plants indicated that they lost the niche differentiation of the P source under drought stress. Additionally, it was observed that foliage water content, WUE, N contents, and N and P sources were significantly affected by interspecific competition, and Broussonetia papyrifera benefited from water competition under moderate drought. Our results indicate that plants have different competition and niche differentiation modes to different nutrients under drought stress, and the effect of interspecific water competition should be seriously considered in mixed forests in semiarid areas.

In terms of lifestyle, bacterioplankton can be classified as free-living (FL) and particle-attached (PA) forms, and both play essential roles in biogeochemical cycling in aquatic ecosystems. Structure, distribution, and community assembly of FL and PA bacteria in plateau riverine waterbodies are largely unknown. Therefore, we explored the seasonal dynamics of FLand PA bacterial communities in the Wujiangdu reservoir, Yungui Plateau using 16S rRNA gene high-throughput sequencing. Results revealed there was a significant environmental heterogeneity in Wujiangdu reservoir seasonally. The dominant phylum was Actinomycetota for FL and Pseudomonadota for PA bacteria. Species richness and diversity was higher in autumn and winter compared to spring and summer. In general, PA diversity was greater than FL, but with some temporal variations. Species turnover was the major contributor to β-diversity of both FL and PA lifestyles, and significant differences were noticed between FL and PA bacterial community composition. Distinct co-occurrence network patterns implied that more connections exist between FL bacteria, while more complex PA networks were in parallel to their greater diversity and stronger interactions in biofilms on particles. Dispersal limitation was the major driving force for both FL and PA bacterial community assembly. Deterministic processes were of relatively low importance, with homogeneous selection for FL and heterogeneous selection for PA bacteria. Temperature was the most important environmental driver of seasonal bacterial dynamics, followed by nitrate for FL and Secchi depth for PA bacteria. This study allows for a better understanding of the temporal variability of different bacteria lifestyles in reservoirs in the vulnerable and rapidly changing plateau environment, facilitating further microbial research related to global warming and eutrophication.

Tree species adopt diverse drought resistance strategies, which are crucial for the ability of karst vegetation to adapt to drought stress. However, our understanding of how to differentiate these strategies remains limited, particularly with respect to identifying indicator traits that can accurately distinguish the drought resistance strategies used by different species. In this study, we use principal component analysis based on functional traits to distinguish the drought resistance strategies of Platycladus orientalis and Broussonetia papyrifera; we identify key indicator traits reflecting differences in drought resistance strategies by analyzing the correlations of the same traits across different plant species. Most importantly, in this study, stomatal transpiration efficiency is proposed as a novel trait. Principal component analysis based on functional traits can distinguish plant drought resistance strategies. A correlation analysis of the indicators revealed that 2,2-diphenyl-picrylhydrazyl radical-scavenging activity, Δcrown width, stomatal transpiration efficiency, and water use efficiency can serve as critical markers to differentiate the drought resistance strategies of plants. Notably, the stomatal transpiration efficiency of P. orientalis and B. papyrifera exhibited entirely opposite trends under drought stress (r = -0.38); however, investigations of additional tree species are needed to further verify the reliability of stomatal transpiration efficiency as an indicator of different plant drought resistance strategies. These findings improve our ability to effectively differentiate karst plant drought resistance strategies and understand the mechanisms involved.

Previous studies often overlooked the dynamic effects of karst vegetation restoration on soil multi‐trophic biodiversity and the underlying community‐assembly mechanisms. To fill this gap, we performed a seasonal comparative analysis of soil biodiversity, co‐occurrence network architecture, and assembly processes across three representative karst restoration patterns (grass, forest‐grass, and forest). During the wet season, the grass pattern exhibited significantly lower biodiversity than both the forest‐grass and forest patterns by 17%–49%. In the dry season, the forest pattern achieved the highest biodiversity indices and displayed minimal seasonal fluctuation. Vegetation type and season jointly shaped soil biotic co‐occurrence networks: the forest–grass pattern generated the greatest network complexity and connectivity, whereas the dry season fostered tighter network structures. The bacterial community was predominantly driven by heterogeneous selection with a relatively high contribution in the wet season, whereas it was dominated by dispersal limitation in the dry season. In contrast, the fungal community was largely influenced by dispersal limitation across seasons. As for the protist and nematode communities, undominated accounted for a relatively high contribution in the wet season, while dispersal limitation became the dominant driver in the dry season. Moreover, soil moisture, nutrient status, biodiversity, and network properties emerged as the principal drivers of assembly, with their pathways varying by taxon and season. Collectively, our reveal integrated regulation of soil biotic communities by restoration pattern and seasonal dynamics in karst ecosystems, offering a robust theoretical basis for soil‐biota recovery.