亚热带红壤丘陵区季节性干旱成因及其发生规律研究

Study on causes and occurrence rules of seasonal drought in subtropical red soil hilly region

结合多年气象资料系统研究亚热带红壤丘陵区季节性干旱成因与发生规律结果表明 ,该区季节性干旱严重 ,“土壤 作物”干旱年发生概率为 85 .7% ,其中≥中等干旱年发生概率为 5 0 .0 % ,7～ 8月份和 11～ 12月份为年内高发期 ,以夏秋干旱危害最大 ;气候性干旱 (Z值法 )年发生概率为 5 9.5 % ,其中≥中等干旱年发生概率为31.0 %。“土壤 作物”干旱明显大于气候性干旱 ,且二者发生概率和危害程度均为 2 0世纪 90年代 >80年代 >70年代 >6 0年代 ,表明红壤丘陵区抵御季节性干旱的能力呈下降趋势 ,农业生态系统抗逆性能仍在不断退化。

The causes and occurrence rules of seasonal drought in the subtropical red soil hilly region were systematically studied by analyzing the meteorological data. The results show that the occurrence probability for 'soil-plant' drought is 85.7%, among which that of moderate or severe drought is 50% or so. The highly frequent drought occurs in the period from July to August and from November to December each year. The drought occurring in July and August can cause a great damage to crops. The occurrence probability for climate-induced drought is 59.5%,among which that of moderate or severe drought is 31.0%. The 'soil-plant' drought is more serious than the climate-induced one. The order of both the probabilities of these two kinds of drought and the extent of damage are 1990s>1980s>1970s>1960s, indicating that it is decreasing for the ability of the red soil hilly region to resist the seasonal drought, declining for the agro-ecosystem to resist the stress.