In arid desert areas, Haloxylon ammodendron plays an important role in maintaining the ecological balance of desert oases. However, there are few studies on the physiological characteristics of Haloxylon ammodendron under an environmental gradient. Here, we studied the changes in the morphological and photosynthetic characteristics and their correlations in Haloxylon ammodendron in the four habitats of the Ebinur Lake wetland. Our results show that in high-water and high-salt habitats, photosynthesis is affected by “stomata restriction,” while in other habitats, photosynthesis is mainly affected by “non-stomata restriction.” In addition, when the soil conditions were good, Haloxylon ammodendron chose leaf construction featuring high specific leaf area, while when the soil conditions were worse, it chose an opposite leaf construction model to ensure the optimal allocation of carbon assimilation products in heterogeneous habitats. This study will deepen our understanding of the trade-off strategy between the accumulation and distribution of plant photosynthate in special habitats in arid areas. The results are of theoretical value for analysis of the ecological adaptation mechanisms of plants in arid desert areas.

Exploring the structural characteristics of arid soil microbial communities and their assembly mechanisms is important for understanding the ecological characteristics of arid zone soils and promoting ecological restoration. In this study, we used Illumina high-throughput sequencing technology to study soils in the arid zone of the Lake Ebinur basin, determined the differences among soil microbial community structures in the study area under different water–salt gradients, and investigated the effects of environmental factors on microbial community structure and assembly mechanisms. The results show the following: the microbial community alpha diversity exhibited a significantly higher low water–salt gradient (L) than high water–salt gradient (H) and medium water–salt gradient (M). The pH was most strongly correlated with soil microbial community structure, where the alpha diversity indices of the bacterial community and fungal community were significantly negatively correlated with pH, and the Bray–Curtis distance of bacterial community was significantly positively correlated with pH (p < 0.05). The complexity of bacterial community co-occurrence networks showed a significantly higher L than H and M, and the complexity of fungal community co-occurrence network showed a significantly lower L than H and M. The cooperative relationship of H and M in the co-occurrence networks was stronger than that of the L, and the key species of the microbial co-occurrence network were different under different water–salt gradients. Stochastic processes dominated the assembly mechanism of the microbial community structure of soil, and the explanation rates of deterministic and stochastic processes were different under different water–salt gradients, with the highest explanation rate of stochastic processes on the L accounting for more than 90%. In summary, the soil microbial community structure and assembly mechanisms significantly differed across water–salt gradients, and these findings can help provide a reference for further research on soil microbiology in arid zones.

Understanding the relationship between biodiversity and ecosystem multifunctionality is popular topic in ecological research. Although scale is an important factor driving changes in biodiversity and ecosystem multifunctionality, we still know little about the scale effects of the relationship between the different dimensions of biodiversity and ecosystem multifunctionality. Using plant communities in the northwest of the Qira Desert Ecosystem National Field Research Station of the Chinese Academy of Sciences in Qira County, Xinjiang, as the study object, we explored the scale effects of plant diversity and ecosystem multifunctionality at different sampling scales (5 m × 5 m, 20 m × 20 m, and 50 m × 50 m) and the relative contribution of different dimensions of diversity (species diversity, functional diversity, and phylogenetic diversity) to variation in ecosystem multifunctionality. At different scales, a significant scale effect was observed in the relationship between plant diversity and ecosystem multifunctionality. Species diversity dominated ecosystem multifunctionality at large scales (50 m × 50 m), and species diversity and ecosystem multifunctionality varied linearly between scales. Functional diversity made the greatest contribution in small scales (5 m × 5 m), and the relationship between phylogenetic diversity and ecosystem multifunctionality tended to show a single-peaked variation between scales, with a dominant effect on multifunctionality at the mesoscale (20 m × 20 m). The results of the study deepen the understanding of the scale effect of the relationship between plant diversity and ecosystem multifunctionality in arid desert areas, and help to further conserve plant diversity and maintain ecosystem multifunctionality.

Afforestation is a widely used method of controlling desertification globally as it significantly impacts the soil quality, microbial community structure, and function. Investigating the effects of various artificial vegetation restoration models on soil microbial communities is crucial in understanding the mechanisms involved in combating desertification. However, research on this topic in arid, desertified regions is limited. In this study, we collected soil samples from two types of artificial forests (single species and mixed species) and bare desert soils in desertified areas of Northwest China to explore the impact of afforestation on soil nutrients, the microbial community composition, network relationships, and carbohydrate degradation abilities using metagenomic sequencing techniques. Our findings indicate that afforestation significantly enhances the soil moisture, total carbon, available phosphorus, and total nitrogen levels. The soil under mixed-species forests exhibited significantly higher levels of total carbon, total phosphorus, available phosphorus, and total nitrogen than that under single-species forests. Following afforestation, the populations of Pseudomonadota, Acidobacteriota, and Cyanobacteria increased significantly, whereas Actinomycetota decreased markedly. In single-species forests, Pseudomonadota and Bacillota were enriched, whereas Chloroflexota, Planctomycetota, and Acidobacteriota were more prevalent in mixed-species plantations. Afforestation increases the complexity and stability of microbial community networks. Afforestation enhances microbial metabolic activity, particularly increasing the abundance of carbon degradation functional genes in forest soils compared to bare desert soils. Mixed-species plantations outperform single-species forests in enhancing carbohydrate metabolism, amino acid metabolism, and the biodegradation and metabolism of xenobiotics. The abundance of functional genes associated with the degradation of starch, cellulose, hemicellulose, chitin, and pectin in mixed-species forests was significantly greater than in single-species plantations. Our study shows that mixed-species afforestation effectively improves the soil quality, enhances the stability of soil microbial communities, and bolsters the carbon cycle in arid regions prone to desertification. The reciprocal relationship between microorganisms and plants may serve as an intrinsic mechanism by which mixed-species afforestation more effectively controls desertification.

Studying the impact of biodiversity on ecosystem multifunctionality is helpful for clarifying the ecological mechanisms (such as niche complementary effects and selection) of ecosystems providing multiple services. Biodiversity has a significant impact on ecosystem versatility, but the relative importance of functional diversity and dominant species to ecosystem functions needs further evaluation. We studied the desert plant community in Ebinur Lake Basin. Based on field survey data and experimental analysis, the relationship between the richness and functional diversity of dominant species and the single function of ecosystem was analyzed. The relative importance of niche complementary effect and selective effect in explaining the function of plant diversity in arid areas is discussed. There was no significant correlation between desert ecosystem functions (soil available phosphorus, organic matter, nitrate nitrogen, and ammonium nitrogen) and the richness of the dominant species Nitraria tangutorum (p < 0.05). Soil organic matter and available phosphorus had significant effects on specific leaf area and plant height (p < 0.05). Functional dispersion (FDis) had a significant effect on soil available phosphorus, while dominant species dominant species richness (SR) had no obvious effect on single ecosystem function. A structural equation model showed that dominant species had no direct effect on plant functional diversity and ecosystem function, but functional diversity had a strong direct effect on ecosystem function, and its direct coefficients of action were 0.226 and 0.422. The results can help to explain the response mechanism of multifunctionality to biodiversity in arid areas, which may provide referential significance for vegetation protection and restoration for other similar areas.

Salt stress is a key environmental factor that has adverse effects on plant growth and development. High salinity induces a series of structural and functional changes in the morphological and anatomical features. The physiological and biochemical changes in K. foliatum in response to salt stress in natural environments are still unclear. Based on this, this study compared and analyzed the differences in the physiological and biochemical indicators between the leaf and root tissues in high-salt and low-salt habitats, selecting K. foliatum as the research object. The results showed that the chlorophyll contents in the leaves of K. foliatum decreased in the high-salt habitat, while the thicknesses of the upper and lower epidermises, as well as the thicknesses of the palisade tissue, significantly increased. The high-salt environment led to decreases in the N and P contents in the leaves and root tissues of K. foliatum, resulting in changes in the stoichiometric ratio of elements. The concentrations of C, N, and P in the roots of K. foliatum were lower than those in the leaves. The accumulation of Na⁺ in the K. foliatum roots was greater than that in the leaves, and the roots could promote the transport of sodium ions to the leaves. The contents of starch and soluble sugar in the leaves showed higher proportions in the high-salt habitat than in the low-salt habitat, while the changes in the roots and leaves were the opposite. As the salt content increased, the proline contents in the leaves and roots of K. foliatum significantly increased, and the proline contents in the roots of K. foliatum were lower than those in the leaves. The leaves and roots exhibited higher levels of peroxidase and superoxide enzymes in the high-salinity habitat than in the low-salinity habitat. The superoxide dismutase (SOD) activity of the K. foliatum leaves and catalase (CAT) activity of the roots were the “central traits” in the high-salt habitat. In the low-salt habitat, the leaf malondialdehyde (MDA) and root C/N were the central traits of the leaves and roots, indicating that K. foliatum adapts to changes in salt environments in different ways.