Xuhu Wang

As a critical alpine transition zone linking the Qinghai–Tibet Plateau and the Loess Plateau, Gannan Prefecture acts as an important water conservation area in the upper Yellow River basin of China. Based on GLDAS-2.1 surface soil moisture (SSM) datasets spanning 2000–2022 and interpretable machine learning tools (SHAP and ALE), this paper analyzes the spatiotemporal evolution, future trend sustainability, and nonlinear statistical associations between environmental predictors and SSM. The main results were as follows: (1) SSM exhibited a significant upward trend with an annual growth rate of 0.18 kg·m⁻²·a⁻¹ (p < 0.001), and an abrupt turning point occurred in 2017. The spatial pattern of high SSM in the southeast and low SSM in the northwest remained relatively stable, with the centroid migration distance being less than 1.81 km; most regions presented statistically significant moistening trends (p < 0.05). (2) Natural environmental predictors jointly carried 95.79% of the total statistical explanatory weight for modeled SSM variability. Precipitation possessed the highest explanatory proportion (37.93%), followed by temperature (27.30%), potential evapotranspiration (ET_p, 12.26%), elevation (10.44%), and fractional vegetation cover (FVC, 7.77%). One-dimensional ALE curves identified sample-limited statistical breakpoints: SSM gradually plateaued when precipitation reached 650–700 mm, while modeled SSM decreased substantially once ET_p exceeded 800 mm·a⁻¹. Two-dimensional ALE further characterized combined statistical correlations among precipitation, temperature, and ET_p. Model outputs also indicated that FVC above 0.45 corresponded to enhanced soil water retention within the observed sample range, which only reflects statistical patterns captured in this dataset rather than universal regulatory standards. This study offers quantitative statistical understanding of SSM variations across alpine transition zones.

Projecting the spatiotemporal dynamics of the potential distribution of dominant species under climate change is essential for desertification control and vegetation restoration in drylands. Here, we modeled the current (1970–2000) and future (2080–2100) suitable habitats of Caragana korshinskii Kom, an ecologically important shrub species in northwestern China, by constructing an ensemble of eight species distribution models on the Biomod2 platform using three CMIP6 Shared Socioeconomic Pathways (SSP126, SSP370, SSP585) and 40 environmental variables representing climate, soil, topography and drought conditions. Key environmental drivers were identified through variable importance ranking and response curves, while area changes, spatial patterns, and centroid shifts in suitable habitats were quantified. The ensemble model demonstrated good to excellent predictive performance (mean AUC > 0.9, mean TSS > 0.5). Soil base saturation (t-bs) and soil moisture contributed the most (>38%), highlighting the dominant role of edaphic factors. The current total suitable habitat of C. korshinskii is approximately 182.2 × 10⁴ km², with all future scenarios projecting a consistent decline. Under SSP585, habitat loss reached 9.8% with contraction (30.5 × 10⁴ km²) far exceeding expansion (12.6 × 10⁴ km²). The distribution centroid shifted markedly eastward with a minor southward fluctuation, establishing the Ordos–Bayannur region as a stable core habitat. Overall, our findings suggest that the distribution of C. korshinskii is strongly constrained by edaphic and moisture conditions, and future contraction of marginal habitats may compromise ecosystem services.

Epimedium brevicornu is an important medicinal plant in China, whose main bioactive components are flavonoid glycosides. UDP-glycosyltransferases (UGTs) play key roles in flavonoid glycosylation and metabolic diversification. In this study, transcriptome data from four representative production regions in Gansu Province were used to systematically identify and analyze the UGT gene family in E. brevicornu. A total of 359 UGT members were identified, and 168 homologous genes with clear expression evidence were obtained from four geographical populations. Molecular evolutionary analysis showed that most UGT genes were under purifying selection, whereas UGT2, UGT52, UGT57, UGT241, UGT269, and UGT271 exhibited significant signals of positive selection in specific lineages (p < 0.05). Protein interaction analysis indicated that many UGT proteins were closely associated with key enzymes involved in flavonoid biosynthesis, including CHS (TT4), CHI (TT5), F3H, FLS, and DFR, suggesting their potential involvement in flavonoid metabolism. Promoter analysis further revealed a high enrichment of ERF (11,169 occurrences) and MYB (7673 occurrences) transcription factor binding sites in the upstream regions of UGT genes. In addition, UGT57 and UGT241 showed significantly higher expression levels in the QLH population. Molecular docking analysis indicated relatively strong binding affinities with quercetin, with binding energies of −7.23 kcal/mol and −4.62 kcal/mol, respectively. These results suggest that the sequence variation and differential expression of UGT genes may be associated with flavonoid glycosylation and ecological adaptation in Epimedium. This study provides a basis for understanding the evolutionary characteristics and expression patterns of the UGT gene family and offers candidate genes for future studies on flavonoid metabolism.

The synergistic effects of climate change and human activities have profoundly influenced the spatiotemporal dynamics of vegetation in arid and semi-arid regions. In this study, MODIS NDVI data and an integrated methodological approach, including trend analysis, partial correlation, residual regression, and geographical detector modeling, were used to analyze the variations in NDVI in Gansu Province from 2000 to 2022. The results showed the following: (1) The growing-season NDVI in Gansu Province exhibited a significant increasing trend overall (0.0029 per year, p < 0.05). (2) Both the NDVI values and their increasing rates presented a spatial pattern of “higher in the southeast and lower in the northwest”; although low vegetation coverage dominated the entire province, 49.47% of the area showed an extremely significant increasing trend in NDVI (p < 0.01). (3) In the future, the area ratio of regions with improved NDVI to those with degraded NDVI in Gansu Province will be approximately 45.5%:54.5%. (4) The contribution rate of human activities to the spatiotemporal variations in NDVI was higher than that of climate change; however, the synergistic effect of the two factors was greater than their individual effects. (5) Precipitation and solar radiation were the two primary climatic factors affecting NDVI variations in Gansu Province, while human activities played a regulatory role in mediating climate–vegetation interactions. Therefore, we suggest implementing more proactive ecological management and restoration measures to mitigate the impacts of future climate change, particularly in regions where NDVI may degrade in the future.

The dynamics and plant composition of toxic weeds in alpine meadows are strongly influenced by management practices such as livestock grazing. Here, the effect of grazing management on vegetation and soil characteristics within an alpine meadow ecosystem was assessed over a 5-year period. The experimental grazing treatments comprised no grazing (control), light grazing (5 sheep/ha), moderate grazing (10 sheep/ha), and heavy grazing (15 sheep/ha). The characteristics of both edible grass and toxic weeds, along with the soil’s physicochemical and biological properties, were evaluated. Under heavy grazing, the biomass of toxic weeds increased by 15.0%, while the biomass of edible species decreased by 57.0% compared to the control. The findings indicated that after 5 years, the plant composition changed significantly, with edible species such as Taraxacum mongolicum and Tibetia himalaica decreasing and disappearing under moderate and heavy grazing treatments. Conversely, toxic weeds like Stellera chamaejasme and Euphorbia micractina emerged under moderate or heavy grazing. Additionally, the richness of toxic weeds increased from 6.3 under the control to 14.2 under heavy grazing. Regarding soil properties, the levels of soil glucosidase, amylase, and cellulose decreased by 39.0%, 53.0%, and 40.0%, respectively. The amount of available potassium initially decreased and then increased under heavy grazing. The results demonstrated that the quality of the vegetation cover and a soil’s properties directly depend on land management. Overall, light to moderate grazing kept the soil in a better chemical and biological state and kept the biomass of palatable plants at a desirable level, which also controlled the abundance and biomass of toxic weeds. Enhancing soil nutrient conditions, such as by adding nitrate fertilizers, can be effective in restoring grasslands that have been severely degraded by grazing.

As climate change continues to alter species distributions, Pinus bungeana, an endangered conifer of significant ecological and ornamental value, faces heightened vulnerability, underscoring the critical need to understand and predict its future habitat shifts. Here, we used 83 effective geographic distribution records, along with climate, topography, soil, and drought indices, to simulate the potential distribution of suitable ecological niches for P. bungeana under current conditions and across three future time periods (2040–2060, 2060–2080, and 2080–2100) under two shared socioeconomic pathways: SSP126 (low emissions) and SSP585 (high emissions), using the maximum entropy (MaxEnt) model. The results show that the area under the receiver operating characteristic curve (AUC) for all simulations exceeded 0.973, indicating high predictive accuracy. Soil moisture, the minimum temperature of the coldest month, temperature seasonality, isothermality, the precipitation of the wettest quarter, and altitude were identified as key environmental factors limiting the distribution of P. bungeana, with soil moisture and the minimum temperature of the coldest month being the most important factors. Under the current climatic conditions, the potentially suitable ecological niches for P. bungeana were primarily located in Shaanxi Province, southern Shanxi Province, southeastern Gansu Province, northeastern Sichuan Province, Henan Province, and northwestern Hubei Province, covering approximately 75.59 × 10⁴ km². However, under the future climate scenarios, highly suitable areas were projected to contract, with the rate of decline varying significantly between scenarios. Despite this, the total area of potentially suitable ecological niches was predicted to expand in the future periods. Additionally, a pronounced eastward shift in P. bungeana’s distribution was projected, especially under the high-emission SSP585 scenario. These findings provide insights into the potential impacts of climate change on the distribution of P. bungeana, and they offer valuable guidance for its conservation strategies and habitat management in the context of climate change.

Gymnocarpos przewalskii is a rare Tertiary relict species, mainly distributed in desert areas of northwestern China. Changes in rainfall have a significant impact on the physiological characteristics of desert plants. In the present study, the effects of five simulated rainfall levels on the gas exchange parameters, chlorophyll fluorescence characteristics, and antioxidant system of G. przewalskii were studied. The results show that with increased rainfall the net photosynthetic rate (P_n) and transpiration rate increase significantly. The reduction in P_n is caused by stomatal and non-stomatal limitations under decreased rainfall. Decreased rainfall markedly improves the instantaneous water-use efficiency of leaves. With increased rainfall, the maximum photosynthetic rate, apparent quantum efficiency, and light utilization range significantly increase. Under reduced rainfall, the chlorophyll content, maximum photochemical efficiency of PSII, and steady-state optical quantum efficiency decrease and photoinhibition is caused in the PSII system. A rainfall reduction of 30% leads to massive production of superoxide anions and hydrogen peroxide, causing obvious peroxidation damage. Meanwhile, superoxide dismutase, peroxidase, and catalase in the leaves are significantly enhanced to remove excess reactive oxygen species and alleviate the injury to photosynthetic apparatus. Our study reveals the effect of rainfall changes on the photosynthetic characteristics and antioxidant system of G. przewalskii, and can improve understanding of the adaptive strategies of desert plants under future precipitation changes in northwestern China.

The Zuli River is in the northwest of the Loess Plateau. As an important center of production and domestic water source, variations in the water quality of this basin and their influencing factors are important considerations for improving the river water environment. In order to identify and predict changes in the water quality of the watershed, the following water quality indicators, namely, dissolved oxygen content (DO), five-day biological oxygen demand (BOD₅), ammonia nitrogen concentration (NH₃-N), the high-manganese salt index (COD_Mn), volatile phenol concentration (VP), total phosphorus (TP), fluoride concentration (F⁻), and nitrite nitrogen concentration (NO₃-N), were studied together with their change trends, influencing factors, and main variation cycles in the basin from 2001 to 2021. The results were as follows: (1) All the water quality indicators except for DO and F- showed an increasing trend before 2011, and DO showed an extreme, significant downward trend. There was an increase in the content of pollutants in the water caused by chemical fertilizer and aquaculture, resulting in a decrease in the DO content. (2) There was an extreme, significant upward trend in DO after 2011, while a significant downward trend was observed in the other water quality indicators except for NO₃-N. (3) According to the main variation cycle of the other water quality indicators, the DO will remain in its peak period, while the other water quality indicators except for NO₃-N will remain in a trough period (which began in 2021). The increase in precipitation and runoff reduced the content of pollutants in the water. Therefore, the overall water quality of the Zuli River Basin gradually improved after 2011. This may be due to (1) increased precipitation and runoff, thereby diluting the concentration of pollutants in the river, or (2) a decreased concentration of pollutants entering the river with the decrease in soil erosion.