The stoichiometric characteristics of plant nitrogen (N) and phosphorus (P) and their correlations with soil properties are regarded as key for exploring plant physiological and ecological processes and predicting ecosystem functions. However, quantitative studies on the relative contributions of water–salt gradients and nutrient gradients to plant stoichiometry are limited. In addition, previous studies have been conducted at the plant species and individual levels, meaning that how community-scale stoichiometry responds to soil properties is still unclear. Therefore, we selected typical sample strips from 13 sampling sites in arid regions to assess the leaf N and P levels of 23 species of desert plants and measure the corresponding soil water content, total salt content, total nitrogen content, and total phosphorus content. The aim was to elucidate the main soil properties that influence the stoichiometric characteristics of desert plants and compare the individual and community responses to those soil properties. Our results indicated that the growth of desert plants is mainly limited by nitrogen, with individual plant leaf nitrogen and phosphorus concentrations ranging from 4.08 to 31.39 mg g⁻¹ and 0.48 to 3.78 mg g⁻¹, respectively. Community stoichiometry was significantly lower than that of individual plants. A significant correlation was observed between the mean N concentration, P concentration, and N:P ratio of plant leaves. At the individual plant scale, aridity significantly reduced leaf N and P concentrations, while high salt content significantly increased leaf N concentrations. At the community scale, aridity had no significant effects on leaf nitrogen or phosphorus stoichiometry, while high salinity significantly increased the leaf N:P ratio and there were no significant interactions between the aridity and salinity conditions. No significant effects of soil nutrient gradients were observed on plant N and P stoichiometric characteristics at the individual or community levels. These results suggest that individual desert plants have lower leaf N and P concentrations to adapt to extreme drought and only adapt to salt stress through higher leaf N concentrations. The N and P stoichiometric characteristics of desert plant communities are not sensitive to variations in aridity and salinity in this extreme habitat. The results of this study could enhance our perceptions of plant adaptation mechanisms to extreme habitats within terrestrial ecosystems.

The response of plants to climate change has become a topical issue. However, there is no consensus on the synergistic processes of the canopy and trunk growth within different vegetation types, or on the consistency of the response of the canopy and trunk to climate change. This paper is based on Normalized Difference Vegetation Index (NDVI), tree-ring width index (TRW) and climate data from the Irtysh River basin, a sensitive area for climate change in Central Asia. Spatial statistical methods and correlation analysis were used to analyze the spatial and temporal trends of plants and climate, and to reveal the differences in the canopy and trunk response mechanisms to climate within different vegetation types. The results show a warming and humidifying trend between 1982 and 2015 in the study area, and NDVI and TRW increases in different vegetation type zones. On an interannual scale, temperature is the main driver of the canopy growth in alpine areas and precipitation is the main limiting factor for the canopy growth in lower altitude valley and desert areas. The degree of response of the trunk to climatic factors decreases with increasing altitude, and TRW is significantly correlated with mean annual temperature, precipitation and SPEI in desert areas. On a monthly scale, the earlier and longer growing season due to the accumulation of temperature and precipitation in the early spring and late autumn periods contributes to two highly significant trends of increase in the canopy from March to May and August to October. Climatic conditions during the growing season are the main limiting factor for the growth of the trunk, but there is considerable variation in the driving of the trunk in different vegetation type zones. The canopy growth is mainly influenced by climatic factors in the current month, while there is a 1–2-month lag effect in the response of the trunk to climatic factors. In addition, the synergy between the canopy and the trunk is gradually weakened with increasing altitude (correlation coefficient is 0.371 in alpine areas, 0.413 in valley areas and 0.583 in desert areas). These findings help to enrich the understanding of the response mechanisms to climate change in different vegetation type zones and provide a scientific basis for the development of climate change response measures in Central Asia.

Each of the NDVI, EVI, NIRv, and kNDVI has varying strengths and weaknesses in terms of representing vegetation dynamics. Identifying the comparative advantages of these indices is crucial to objectively determine the dynamics of vegetation in dryland. In this study, Central Asia was selected as the research area, which is a typical drought-sensitive and ecologically fragile region. The Mann–Kendall trend test, coefficient of variation, and partial correlation analyses were used to compare the ability of these indices to express the spatiotemporal dynamics of vegetation, its heterogeneity, and its relationships with temperature and precipitation. Moreover, the composite vegetation index (CVI) was constructed by using the entropy weighting method and its relative advantage was identified. The results showed that the kNDVI exhibited a stronger capacity to express the relationship between the vegetation and the temperature and precipitation, compared with the other three indices. The NIRv best represented the spatiotemporal heterogeneity of vegetation in areas with a high vegetation coverage, while the kNDVI had the strongest expressive capability in areas with a low vegetation coverage. The critical value for distinguishing between areas with a high and low vegetation coverage was NDVI = 0.54 for temporal heterogeneity and NDVI = 0.50 for spatial heterogeneity. The CVI had no apparent comparative advantage over the other four indices in expressing the trends of changes in vegetation coverage and their correlations with the temperature and precipitation. However, it enjoyed a prominent advantage over these indices in terms of expressing the spatiotemporal heterogeneity of vegetation coverage in Central Asia.

Ecological network construction has been widely accepted and applied to guide regional ecological conservation and restoration. For arid regions, ecological networks proposed based on ecological risk assessments are better aligned with the sensitive and fragile characteristics of local ecosystems. This study assesses landscape ecological risk in Wensu County, located on the southern slope of the Tianshan Mountains in the arid region of northwestern China, and it further proposes an optimized ecological network. A multidimensional framework composed of the natural environment, human society, and landscape patterns was employed to construct an ecological risk assessment system. Spatial principal component analysis (SPCA) was applied to identify the spatial pattern of ecological risk. Morphological spatial pattern analysis (MSPA) and a minimum cumulative resistance (MCR) model integrated with circuit theory were used to extract the ecological sources and delineate the ecological corridors. The results reveal significant spatial heterogeneity in terms of ecological risk: Low-risk zones (16.26%) are concentrated in the southwestern forest and water areas. In comparison, high-risk zones (28.27%) are mainly distributed in the northern mountainous mining region. A total of 24 ecological source patches (4105.24 km²), 44 ecological corridors (313.6 km), 39 ecological pinch points, and 38 ecological barriers were identified. Following optimization, the Integral Index of Connectivity (IIC) increased by 89.04%, and the Landscape Coherence Probability (LCP) rose by 105.23%, indicating markedly enhanced ecological connectivity. The current ecological network exhibits weak connectivity in the south and fragmentation in the central region. Targeted restoration of critical nodes, optimization of corridor configurations, and expansion of ecological sources are recommended to improve landscape connectivity and promote biodiversity conservation.

Asymmetric diurnal warming is a salient feature of global climate change, and its reshaping of hydrological and carbon processes in terrestrial ecosystems has attracted increasing attention. Water use efficiency (WUE), defined as the ratio of gross primary productivity to evapotranspiration, serves as a key indicator coupling vegetation water consumption with carbon sequestration; however, how daytime and nighttime warming directly and indirectly drive divergent WUE responses through soil moisture and evapotranspiration pathways—and whether these responses are governed by soil-moisture thresholds—remains insufficiently explored in arid grasslands. In this study, the arid and semi-arid grasslands of northern Xinjiang were selected as the study area, and the spatiotemporal heterogeneity of diurnal land surface temperature, evapotranspiration components, soil moisture, and WUE during the growing season was systematically analyzed to identify the key hydrological factors and driving pathways through which diurnal warming regulates WUE. The results showed that: (1) nighttime warming in the grasslands of northern Xinjiang was significantly stronger than daytime warming during the study period, with significant nighttime warming (p < 0.05) detected over 86.31% of the area, far exceeding the 16.62% observed for daytime warming, and the diurnal temperature range narrowing continuously at a rate of 0.02 °C per year; (2) over the same period, WUE exhibited an overall non-significant declining trend with pronounced spatial heterogeneity, with areas of significant increase concentrated in the Junggar Basin, whereas areas of significant decrease were clustered on the northern slope of the Tianshan Mountains, reflecting divergent evapotranspiration and productivity responses under contrasting moisture regimes; (3) LAI emerged as the most critical independent factor regulating WUE variation, with daytime warming exerting a significant negative effect on WUE primarily by depleting soil moisture, suppressing LAI, and intensifying vapor pressure deficit-driven evapotranspiration stress, whereas nighttime warming across the broader region exerted a positive compensatory effect by promoting LAI growth and sustaining soil moisture availability; (4) these pathway reversals are governed by a soil-moisture threshold: in the arid basin where WUE increased significantly, the effects of nighttime warming on soil moisture and LAI shifted from promotive to inhibitory, and the direct effect of daytime warming likewise reversed from positive to negative, revealing that the apparent WUE increase reflects a passive hydrological response in which transpiration is preferentially suppressed under severe water deficit rather than an improvement in ecosystem function. These findings demonstrate that diurnal warming effects on grassland water use exhibit pronounced soil-moisture threshold dependence and spatial heterogeneity. Our study highlights that substituting daily mean temperature for separate daytime and nighttime temperatures masks the opposing effects of asymmetric warming on coupled water consumption and carbon processes, and underestimates the sensitivity of arid grassland hydrological cycles to climate warming. This study provides a new mechanistic basis for optimizing parameters in carbon–water cycle models and for differentiated water resource management in arid grassland regions.

How plant traits and soil factors jointly regulate aboveground biomass (AGB) along soil moisture gradients is central to arid-land ecology. Along a soil moisture transect in China’s Kalamaili Nature Reserve, we integrated soil properties with trait-based community metrics to identify the drivers of AGB. AGB was regulated by soil water content (SWC) through both direct effects and indirect nitrogen-mediated pathways, whereby higher total nitrogen increased community-weighted maximum height. The AGB-SWC relationship was strongly nonlinear, with a clear threshold near 28% SWC: responses were weak below this point but increased sharply above it. Driver importance shifted with aridity, as the positive effect of plant height weakened under extreme drought, and its interaction with SWC shifted from synergistic in dry conditions to antagonistic in wetter conditions. These results reveal soil moisture thresholds and context-dependent trait-resource coupling that inform predictions and management of productivity in arid ecosystems.