The response of microbiomes to salinity has been clarified in different geographic scales or ecosystems. However, how soil microbial community structure and interaction respond to salinity across wide salinity range and climatic region is still unclearly resolved. To address this issue, we examined the microbial community’s composition in saline soils from two climatic regions (coastal wetland and arid desert). Our research confirms that soil salinity had a negative effect on soil nutrient content. Salinity decreased the relative abundance of bacteria, but increased archaea abundance, leading to the shifts from bacteria dominant community to archaea dominant community. Low-water medium-salinity soil (LWMS) had the most complex archaeal community network, whereas for bacteria, the most complex bacterial community network was observed in low-water high-salinity soils (LWHS). Key microbial taxa differed in three salinity gradients. Salinity, soil water content, pH, total nitrogen (TN), and soil organic carbon (SOC) were the main driving factors for the composition of archaeal and bacterial community. Salinity directly affected archaeal community, but indirectly influenced bacteria community through SOC; pH affected archaeal community indirectly through TN, but directly affected bacterial community. Our study suggests that soil salinity dramatically influences diversity, composition, and interactions within the microbial community.

The nitrogen deposition process, as an important phenomenon of global climate change and an important link in the nitrogen cycle, has had serious and far-reaching impacts on grassland ecosystems. This study aimed to investigate the survival adaptation strategies of plants of different functional groups under nitrogen deposition, and the study identified the following outcomes of differences in biomass changes by conducting in situ simulated nitrogen deposition experiments while integrating plant nutrient contents and soil physicochemical properties: (1) nitrogen addition enhanced the aboveground biomass of grassland communities, in which Poaceae were significantly affected by nitrogen addition. Additionally, nitrogen addition significantly influenced plant total nitrogen and total phosphorus; (2) nitrogen addition improved the plant growth environment, alleviated plant nitrogen limitation, and promoted plant phosphorus uptake; and (3) there was variability in the biomass responses of different functional groups to nitrogen addition. The level of nitrogen addition was the primary factor affecting differences in biomass changes, while nitrogen addition frequency was an important factor affecting changes in plant community structure.

Nitrogen inputs exert significant impacts on plant species composition and ecosystem stability within alpine grasslands. The exploration of leaf functional traits holds great potential in uncovering plants’ adaptive strategies and competitive edges, and is pivotal in comprehending the ramifications of nitrogen inputs on biodiversity. In this study, the Bayanbulak grassland was selected as the research subject to investigate the impact of nitrogen addition on leaf functional traits of different plant functional groups. Specifically, various gradients of nitrogen addition were established to observe changes in leaf dry matter content (LDMC) and leaf area (LA) among three distinct plant functional groups. Furthermore, structural equation modeling (SEM) was employed to analyze the pathways through which nitrogen addition influenced the LDMC of these plant functional groups. The results were as follows: (1) LA and leaf length (LL) of Poaceae changed significantly (p < 0.05) under different N addition gradients, and leaf nutrient contents of Poaceae, Rosaceae and Fabaceae showed significant changes under different N addition gradients. (2) Pearson correlation analyses showed that total nitrogen (TN), total carbon (TOC) and leaf width (LW) of Rosaceae leaves had a significant positive correlation, and the TOC and total phosphorus (TP) of Fabaceae leaves showed a significant negative correlation. (3) SEM of the three plant functional groups showed direct and indirect effects of N addition on leaf dry matter content of Poaceae and Rosaceae, and only indirect effects on Fabaceae.

The restoration of alpine grasslands has garnered significant attention across various sectors. Historically, natural restoration has been the primary approach for grassland recovery, characterized by its prolonged duration. To expedite the recovery of degraded grasslands, it is essential to identify the limiting factors of restoration, enabling efficient and rapid recovery. Appropriate nitrogen (N) addition levels have been considered a potential strategy to enhance the recovery of grassland ecosystems and augment their ecological benefits. However, the effectiveness of N addition in alpine grassland restoration remains debated. This study investigated the impact of five N addition levels (CK: control [0 g/m²]; LN: low N [5 g/m²]; MN: medium N [10 g/m²]; HN: high N [15 g/m²]; SN: severe N [20 g/m²]) and two experimental approaches (N addition once per year [NPY] and three times per year [NTY] at the same dosages) on plant and soil properties and the maximum restoration capacity of alpine meadows. Our findings reveal three key insights: The level of N addition was the primary factor influencing aboveground plant biomass and coverage. Plant diversity decreased under the NTY regime and increased with NPY in the Bayinbruck grassland. N addition significantly altered soil properties, including pH, salinity, soil organic carbon (SOC), soil‐available phosphorus (AP), and soil total phosphorus (TP). Notably, soil TP, total nitrogen (TN), and AP substantially impacted plant community structure and diversity. Based on structural equation model (SEM) and analysis of variance (ANOVA), optimal grassland restoration was achieved with the HN (15 g/m²) treatment under NPY and the MN and HN (10 and 15 g/m²) treatments under NTY. Overall, our study offers crucial insights into the conservation, management, and restoration of grassland ecosystems on the Bayinbruck Plateau. It underscores the significance of N addition effects on plant communities, vegetation restoration, and soil properties.

The Water-Level-Fluctuation Zones (WLFZ) of the Lower Jinsha River, as a typical transition areas between land and water, show crucial ecological functions. However, the relationship between soil nutrients and microbial communities in different plant communities of the WLFZ is poorly understand. Therefore, we chose four typical plant communities, including Parthenium hysterophorus (P. hysterophorus), Ziziphus mauritiana (Z. mauritiana), Cynodon dactylon (C. dactylon), Zea mays (Z. mays), as a long-term plant communities experiment-monitoring site in a WLFZ of the Lower Jinsha River. By using high-throughput sequences, Mantel test and Mediation model, we explored the changing characteristics of soil nutrients and microbial communities, especially bacteria and fungi, and their driving role in the microbial stability in four typical plant communities. The results indicated that soil properties and enzyme activities noticeably changed among four types of different plant communities in the WLFZ, of which their P. hysterophorus and Z. mauritiana treatments were eventually higher than their of Z. mays and C. dactylon treatments. In the bacteria and fungi communities, the OTU number of P. hysterophorus and Z. mauritiana treatments were higher than their of C. dactylon and Z. mays treatments, which showed that the bacterial biomarkers only explained with the order, but the fungal biomarkers could explain with species. The bacterial and fungal diversity among four types of different plant communities in the WLFZ significantly changed such that the bacterial and fungal explanations of principal coordinate analysis (PCoA) was at 42.45% and 28.17%, respectively, and the anosim analysis of bacteria and fungi showed the p was 0.001 and the R was at 0.6995 and 0.7491. The bacterial and fungal co-occurrence network patterns presented that the bacterial community structure of the C. dactylon and P. hysterophorus treatments were the most complicated under the Z. mauritiana and Z. mays treatments, whereas the communities stability of C. dactylon and P. hysterophorus treatments were notably lower than that of their Z. mauritiana and Z. mays treatments. Lastly, the CCA, mantel test and intermediary analysis indicated pH served as the primary direct driver in the Z. mauritiana community, soil moisture exerted dominant effects in Z. mays and P. hysterophorus, while in C. dactylon, bacterial stability was indirectly modulated by pH mediated through SMC changes. This study highlights the major role of soil nutrients and enzyme activities in driving ecosystem stability of bacterial and fungal communities in four different plant communities in the WLFZ.