The impact of climate change on the spatial evolution of citrus industry production in China

【Objective】As the largest producer and consumer of citrus in the world, China’s citrus industry has undergone significant shifts in its spatial patterns in recent years under the influence of climate change, primarily reflected in the relocation and concentration of production areas. Investigating the key climatic factors driving the spatial evolution of citrus production is of great significance for optimizing industrial layout and ensuring sustainable development. This study aims to systematically analyze the spatial evolution of China’s citrus industry from 2002 to 2022, identify the main climatic drivers of its spatial changes, and provide a scientific basis for policy formulation and industrial planning. 【Methods】This study takes 19 major citrus-producing provinces (regions) in China as the research subjects and utilizes panel data from 2002 to 2022. By integrating spatial econometric models and statistical analysis methods, it systematically explores the spatial agglomeration patterns of citrus production and its influencing factors. Specific methods include: first, using the global Moran’s I to evaluate the spatial clustering characteristics of citrus production and revealing the positive correlation and temporal trends in its spatial distribution. The spatial correlation of citrus production in China is analyzed through the global Moran’s I, while local Moran’s I (LISA) is applied to identify high- high clusters and low-low clusters, further revealing spatial heterogeneity among regions. Second, a two-way fixed effects model is constructed to quantify the effects of climatic factors (annual average temperature, precipitation, frost days, hail days, average maximum temperature, and relative humidity) on the spatial distribution of citrus production. Through model fitting, the contribution of each factor to the spatial evolution of citrus production is determined, and regional differences are analyzed. Key climatic variables focus on annual average temperature and precipitation, exploring their impact on the spatial distribution of citrus yield. By classifying precipitation years into wet, normal, and dry years, the relationship between citrus production spatial distribution and precipitation is clarified. Based on these results, ArcMap 10.8.1 and Origin 2024 software are used to visualize the spatial distribution characteristics of different main producing areas and examine regional differences in climatic conditions, providing a basis for formulating regionally differentiated policies.【Results】(1) The spatial distribution of citrus production in China exhibited a three-stage evolutionary characteristic:“random dispersion - strengthened agglomeration - high stability.”From 2002 to 2004, the distribution was random (Moran’s I fluctuated between - 0.009 5 and 0.012 3, P＞0.1). From 2005 to 2015, the agglomeration effect continuously strengthened (Moran’s I peaked at 0.0826, with P ＜ 0.05 after 2007). From 2016 to 2022, it entered a highly stable state (Moran’s I fluctuated between 0.055 and 0.079, showing a significant positive correlation). (2) The distribution of citrus-producing areas showed a clear trend of“shifting to southward and expanding to westward.”Throughout the study period, high- high clusters remained anchored in the South China region at the junction of Guangdong, Guangxi, Hunan, and Jiangxi, while low-low clusters were consistently distributed in high-altitude areas of the north, northwest, and southwest. The GannanXiangnan-Northern Guangxi citrus belt and the citrus belt in the middle and upper reaches of the Yangtze River have become the core production areas, accounting for 61.5% of total production in 2022. (3) The influence of climatic factors on changes in citrus production areas exhibited regional heterogeneity. The annual average temperature (Te) coefficient was 0.929, showing a significantly positive effect at the 10% level. In contrast, the average maximum temperature (Tmax) coefficient was -0.724, indicating a negative trend. Precipitation (Ra) had a coefficient of 0.310, which was significantly positive at the 5% level. The coefficient for hail days (Ha) was -0.193, reflecting a significant negative impact on citrus production layout. The coefficients for relative humidity (Hm) and frost days (Fr) were -0.141 and 0.063, respectively, and were not statistically significant. Regionally, the citrus belt in the upper and middle reaches of the Yangtze River was influenced by annual average temperature, average maximum temperature, relative humidity, and frost days (P ＜ 0.05). The southern Jiangxi-southern Hunan-northern Guangxi citrus belt was primarily affected by annual average temperature, relative humidity, hail days, and frost days. The western Hubei-western Hunan citrus belt showed a significant response to hail days (P ＜ 0.1). The characteristic citrus production zone was affected by the average maximum temperature and the number of frost days (P ＜ 0.1), which was close to the significant level. (4) The effects of different precipitation years on yield varied significantly across regions. Overall, production performed best in normal precipitation years. The Gannan-Xiangnan-Northern Guangxi citrus belt was prone to waterlogging risks in wet years, while the Western Hubei- Western Hunan citrus belt exhibited strong drought resistance in dry years.【Conclusion】This study systematically reveals the spatial evolution of citrus production in China and its climatic influencing factors under climate change. Based on the findings, the following recommendations are proposed: In the Gannan-Xiangnan-Northern Guangxi citrus belt, we should focus on waterlogging prevention and optimizing drainage systems; in specialized citrus production zones, water conservancy infrastructure should be strengthened and rainwater-harvesting agriculture should be developed; in the citrus belt in the middle and upper reaches of the Yangtze River, the water-saving irrigation needs to be improved; in the Western Hubei-Western Hunan citrus belt, the dry farming techniques can be promoted; in the Zhejiang-Fujian-Guangdong citrus belt, its current model should be maintained while emphasizing quality improvement.