Abstract:

Based on the dataset of air temperature and precipitation from 86 stations during 1961 to 2021 and DEM data derived from 1:250000 topographic maps, we analyzed the spatial-temporal variations of key climate factors such as annual mean temperature (T_y), annual extreme minimum temperature (T_min), cold accumulation of average daily temperature ≤10 ℃ from previous December to February (∑(10-t)_12-2), average precipitation in March (R₃) using the methods of linear regression, accumulative anomaly, and inverse distance weighted interpolation. We examined the impacts of climate change on climatic division for litchi planting by combining the changes of four key climate factors for the periods of 1961-1990, 1971-2000, 1981-2010, 1991-2020, before (1961-1997) and after T_y mutation (1998-2021). The results showed that spatial distributions of the four key climate factors for litchi planting varied across different places in Guangdong. Generally, T_y and T_min were higher in south parts than that in north parts and higher in plain than that in mountain regions. ∑(10-t)_12-2 was higher in north parts than that in south parts and higher in mountain than that in plain regions. R₃ increased from southwest to northeast. Under the background of global warming, T_y and T_min showed a significant increasing trend with a rate of 0.2 ℃ and 0.4 ℃ per decade, respectively, whereas R₃ showed an insignificant upward trend and ∑(10-t)_12-2 even showed significant drop with a rate of 14.0 ℃·d per decade. T_y had mutation in 1997. According to the climatic conditions of litchi growth and development, the climatic division for litchi planting could be divided into three regions in Guangdong: suitable region, sub-suitable region, and unsuitable region. The suitable region was mainly distributed in the east of Guangdong, the coast of Pearl River Delta, and the north part of western Guangdong. The sub-suitable region was mainly located in Zhanjiang, Yunfu, and the northern Pearl River Delta. The unsuitable region was concentrated in northern Guangdong, northern Zhaoqing, and the Yunwu Mountains. Due to the climate change, the areas of suitable and sub-suitable regions increased, whereas the area of unsuitable region decreased. Relative to that in 1961-1990, the areas of suitable and sub-suitable regions in 1991-2020 increased by 0.44×10⁶hm² and 1.02×10⁶ hm², respectively, while the area of unsuitable region decreased by 8.09×10⁶ hm². The areas of suitable and sub-suitable regions increased by 0.08×10⁶ and 2.01×10⁶ hm², respectively, while the area of unsuitable region decreased by 2.08×10⁶ hm² after climate mutation (1998-2021) compared to that before climate mutation (1961-1997) in Guangdong.

Key words: climate mutation, division indicator, climatic division, climatic suitability, litchi planting, Guangdong.