As urbanization and industrialization advance, China faces increasingly severe ecological challenges. The Ecological Protection Redline (EPR) policy is a crucial tool for land use management and ecological protection but requires a comprehensive risk assessment method to address ongoing challenges. This study integrated multiple factors with ecological resilience theory to establish a Hazard-Exposure-Vulnerability-Damage-Final Risk framework, assessing the spatiotemporal dynamics and risks of different EPR types in Qinghai Province over 20 years. Path analysis was further used to reveal relationships between risk stages. Results show increasing hazards and exposure in Water Conservation (WC), Biodiversity Maintenance (BM) and Land Desertification (LD) EPR types, with improved water conservation, stable biodiversity, and controlled desertification vulnerability across regions. Integrated risk results show a downward risk trend in WC type, BM type fluctuated but improved, and an initial increase followed by risk decrease in LD type. Path analysis revealed that damage in WC-type EPR was driven by direct hazard impacts, BM-type EPR by vulnerability, and damage in LD-type EPR by indirect effects of hazard through exposure. This study emphasizes the optimization of EPR policies by reducing external disturbances and enhancing ecosystem resilience, providing policy recommendations and practical experience for ecological protection and sustainable land use management.

Soil salinity is one of the most challenging environmental factors affecting rice productivity, particularly in regions with high saline soils such as Egypt. The ability of rice to maintain high yield and quality under saline stress is often limited, leading to significant reductions in productivity. With the increasing salinization of agricultural lands, finding effective agronomic practices and treatments to mitigate salt-induced damage in rice crops is critical for ensuring food security. This study investigates the potential of exogenous glycine betaine (GB) and proline (Pro) applications to mitigate the adverse effects of salt stress on rice (cv. Sakha 108) over two consecutive growing seasons (2021-2022). Treatments of 30 mM GB and 30 mM Pro significantly enhanced dry weight (162.2 and 169.7 g in 2021 and 2022, respectively), plant height (88.94 and 99.00 cm), tiller number (10.58 and 10.33), and grain yield (4.22 and 4.30 t/ha) compared to control groups. Combined treatments of 30 mM GB and 30 mM Pro exhibited the greatest improvements across both years, with maximum dry weight (193.44 and 186.56 g), plant height (112.00 and 112.33 cm), tiller number (15.33 and 16.28), spikelet number per meter (264.00 and 264.05), thousand-kernel weight (70.00 and 73.2 g), and grain yield (6.17 and 6.64 t/ha). Additionally, the combined treatments resulted in the highest harvest index (53.22% in 2021 and 48.94% in 2022), amylose content (24.24% and 20.09%), and protein content (12.33% and 12.00%). Correlation analysis highlighted strong positive relationships among traits, such as plant height with grain yield (r = 0.94), biomass yield (r = 0.92), and harvest index (r = 0.90). Path analysis further demonstrated that thousand-kernel weight and biomass yield had the most significant direct effects on grain yield, with values of 0.43 and 0.42, respectively. Heatmap clustering and principal component analysis (PCA) confirmed the synergistic effects of combined GB and Pro treatments, with the 30P_30GB treatment consistently clustering with high-yield traits, enhancing nitrogen use efficiency and stress resilience. In conclusion, the combined application of glycine betaine and proline significantly enhances the agronomic and chemical traits of rice under salt stress. This study demonstrates that these osmoprotectants improve vegetative growth, grain yield, and quality, with synergistic effects observed at optimal concentrations. The findings highlight the potential of glycine betaine and proline as effective tools for improving salt tolerance in rice, offering practical solutions to address challenges in saline-affected agricultural regions.

Elevation plays a crucial role in modulating the spatiotemporal distributions of climatic variables in mountainous regions, which affects water and energy balances, among which reference evapotranspiration (ET0) is a key hydrological indicator. However, the response of ET0 to climate change with elevation continues to be poorly understood, especially in the Tibetan Plateau (TP) which has elevation variations of more than 4,000m. The spatiotemporal variations of ET0 with elevation were investigated using long-term (1960-2017) meteorological observations from 82 stations on the TP. The results suggest that the average annual ET0 showed an insignificant increasing trend. A significant negative correlation between ET0 and elevation was found (p<.01). The positive trends of ET0 decreased with elevation, whereas the negative trends of ET0 increased significantly with elevation (p<.05). The magnitude of trends of ET0 becomes smaller at higher-elevation stations. Sensitivity analysis indicated that ET0 was most sensitive to shortwave radiation (R-s). Moreover, the sensitivities of temperature (T) and wind speed (U) significantly decreased with elevation, whereas those of R-s and vapour pressure deficit (VPD) increased slightly with elevation. The contribution and path analyse indicated that increasing VPD was the dominant contributor to the increase in ET0. The effect of elevation on ET0 variation mainly depended on the tradeoff between the contributions of U and VPD. U was the largest contributing factor for the change in ET0 below 2,500m, whereas VPD was the primary contributor to the increase in ET0 above 2,500m. This study provides insights into the response of ET0 to climate change with elevation on the TP, which is of great significance to hydrometeorological processes in high-altitude regions.

While the direct impact of climate change on reference evapotranspiration (ET0) has been extensively studied, there is limited research on the indirect impact resulting from the interaction between climatic variables. This gap hinders a comprehensive understanding of climate change effects on ET0. Additionally, there is scarce exploration into the quantitative effect of freeze-thaw cycles on ET0 variation. In this study, we employed path analysis and dependent variable variance decomposition methods to discern the direct and interactive effects of climatic variables on ET0 in the Tibetan Plateau from 1960 to 2022. Annual ET0 exhibited variation across basins, with the coefficient of variability during the thawed period smaller than that during the non-thawed period. On an annual scale, the largest contribution to ET0 variation came from water vapor pressure deficit (VPD) at 47.7%. This contribution was amplified by its coupled interaction with temperature (T) at 47.1%, although the contribution was partially offset by the interactive effects of VPD with downward shortwave radiation and wind speed at -2.4% and - 27.6%, respectively. During different freezing-thawing periods, VPD primarily controlled ET0 variation, with its interaction with other climatic variables enhancing its impact. Furthermore, soil moisture, influenced by freeze-thaw cycles, exhibited a strong correlation with T and VPD, indicating the significant effect of freeze-thaw cycles on ET0 variation. The weak correlation between ET0 and NDVI suggested that vegetation growth had a limited regulatory effect on ET0. These findings provide valuable insights into the impact of interactions between climatic variables on hydrological processes, enhancing our understanding of the interactive roles of hydrometeorological variables.

The Yangtze River and the Huang River are the two largest rivers in China. Annual runoff ratios (runoff/precipitation, denoted as RR) of the head regions of these two basins (HYR and HHR, respectively) have significantly decreased over the past several decades, closely related to changes in water storage capacity (WSC) and terrestrial water storage (TWS). However, such effects have rarely been quantified due to limitations associated with complicated arctic hydrological processes and the absence of long-term reliable TWS data. In this study, a TWS reconstruction dataset (TWSrec) was validated, and demonstrated good performance in capturing TWS variations derived from the Gravity Recovery and Climate Experiment (GRACE) and in the terrestrial water budget for these two head regions. Long-term (1980-2015) changes in TWS and WSC were then detected and their effects on RR were quantified through trend detection, change point analysis, and path analysis. Results showed that TWS increased significantly with a rate of 27.6 mm/10 yr and 19.8 mm/10 yr at HYR and HHR, respectively. These increases were mainly caused by wetting (increases in precipitation) or soil moisture increases from the TWS component perspective. WSC (represented as the ratio of TWS to precipitation) gradually enlarged in response to continuous climate warming. RR decreased significantly with rates of 2.0%/10 yr at HYR and 3.6%/10 yr at HHR, attributed to the increased evaporation ratio (similar to 80%) and increased WSC (similar to 20%) in both head regions. Further analysis suggested that permafrost degradation under climate warming could increase WSC. These results demonstrate that climate change has resulted in unstable terrestrial water storage at HYR and HHR, and that increases in WSC due to permafrost degradation play an important role in accurately simulating runoff in the Tibetan Plateau and other permafrost-degradation regions.