Responses of Winter Wheat Yield to Drought in the North China Plain: Spatial–Temporal Patterns and Climatic Drivers

Differential responses of crop yields to multi-timescale drought in mainland China: Spatiotemporal patterns and climate drivers

Increasingly frequent and severe droughts pose a growing threat to food security in China. However, our understanding of how different crops respond to multi-timescale drought under varying climatic conditions remains limited, hindering effective drought risk management. To address this knowledge gap, we applied spatial principal component analysis (SPCA) to unveil spatiotemporal patterns in annual yields of major grain crops (rice, wheat, maize) and cotton in response to multi-timescale drought, as indicated by the standardized precipitation evapotranspiration index (SPEI) across China. Subsequently, predictive discriminant analysis (PDA) was employed to identify the primary climatic factors driving these response patterns. The findings indicated that drought-induced interannual variability of crop yields were spatially and temporally heterogeneous, closely tied to the timescale used for drought assessment. Crop types displayed distinct responses to drought, evident in the variations of months and corresponding timescales for their strongest reactions. The initial three principal components, capturing over 65 % of drought-related yield variance, unveiled short- to medium-term patterns for rice, maize, and cotton, and long-term patterns for wheat. Specifically, rice was highly susceptible to drought on a 4-month timescale in September, wheat on a 6-month timescale in May, maize on a 3-month timescale in August, and cotton on a 3-month timescale in September. Moreover, the first three discriminant functions explaining over 90 % of the total variance, effectively distinguish spatiotemporal crop yield response patterns to drought. These patterns primarily stem from seasonal climatic averages, with water balance (precipitation minus potential evapotranspiration) and temperature being the most influential variables (p < 0.05). Interestingly, we observed a weak correlation between drought severity and crop yield in humid conditions, with responses tending to manifest over longer timescales. These findings enhance our comprehension of how drought timescales impact crop yields in China, providing valuable insights for the implementation of rational irrigation management strategies.

Reversal of soil moisture constraint on vegetation growth in North China

The response of vegetation growth to soil moisture varies greatly from space and time under climate change and anthropogenic activities. As an important grain producer in China, the vegetation growth and grain production of North China are constrained by the region's water resources. With the significant increase in vegetation greenness in North China over the last 40 years, it is essential to explore the changes in soil moisture constraints on vegetation growth to water management. However, to what degree vegetation growth responds to soil moisture and how the response varies spatiotemporally in North China remain unclear. In this study, the response patterns of vegetation growth to soil moisture at different depths and the spatiotemporal trend patterns of their relationships were explored thoroughly based on long time series remote sensing data in North China over the past 40 years. The results showed that compared to forests, the growth of grasslands and crops with one maturity per year and two maturity per year in North China was more constrained by soil moisture. Due to the combined effects of climatic conditions and human activities, vegetation growth in North China has been significantly less constrained by soil moisture over the last 40 years. This was especially seen in one maturity per year crop and natural vegetation in Shanxi and central Shandong. However, with the significant increase in temperature, potential evapotranspiration and water demand of the crop, the moisture constraints on vegetation growth in North China have begun to show an increasing trend since the early 2000s, especially for irrigated crop in central and southern North China. These findings highlight a comprehensive understanding of the vegetation response to soil moisture from the time-varying perspective and provide a theoretical basis for water management and appropriate planning of agricultural water use in North China.

Water strategies and water-food Nexus: challenges and opportunities towards sustainable development in various regions of the World

The twenty-first century is witnessing an explosion in global population, environmental changes, agricultural land disintegration, hunger, and geopolitical instabilities. It is difficult to manage these conditions or standardize improvement systems without thinking of the three main elements or subsystems that are necessary for any meaningful development-namely water (W), energy (E), and food (F). These key elements form what is globally agreed upon as the "WEF Nexus." While considering them, one should think about the other key factors that influence WEF Nexus, including population's growth, impacts of environmental changes (including climate change), moderation and adaptation regimes to climate change and climate resilience, loss of biodiversity, and sustainable nature. Together, the WEF Nexus subsystems represent a framework to ensure environmental protection that should be seen as an ethical and socioeconomic obligation. Issues, such as protection of water resources, and strategies and management tools or mechanisms for the use of water assets and agricultural innovations under the obligations of sustainable use, are investigated in this paper. Attention is paid to the relationship between water and food (WF Nexus) or water for food security in various world regions, including the Gulf Cooperation Council (GCC) countries, Central Asia countries and the Caucasus, China, Africa, and Canada. This paper also presents analyses of a great number of up-to-date publications regarding the "Nexus" perspective and its applications and limitations. This paper suggests that the Nexus' approach, in its different concepts (WEF, WE, WF and EF), can promote sustainable development and improve the quality of life of communities, while preserving natural, human, and social capital, addressing sustainability challenges, and protecting natural resources and the environment for long-term use.