气候变暖背景下极端温度对棉花产量的影响以新疆为例
Impacts of extreme temperatures on cotton yields in the context of climate warming: A case study of Xinjiang
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摘要: 在全球气候变暖背景下, 极端温度事件频发, 严重影响作物生产。棉花是我国重要的经济作物, 新疆棉花产量占全球近24%, 研究极端温度事件对新疆棉花产量的影响对保障我国棉花产业高质量发展具有重要意义。本研究基于新疆1990—2019年的历史气象数据和棉花产量数据, 使用Mann–Kendall趋势检验和Sen’s slope方法分析产量的时空变化特征, 并利用copula函数评估棉花产量对极端温度的响应。结果表明, 1990—2019年新疆86%的地区棉花产量呈现极显著的增加趋势(P<0.01)。南疆因极端温度发生导致棉花增产概率超过20%的地区占41.7%, 而北疆只占26.1%。全疆92.6%地区因极端温度发生导致棉花减产的概率低于30%, 减产概率超过30%的地区均集中在北疆。在6个极端气候指标中, 极端最低气温和最高气温对棉花气候产量影响显著。随着极端最低气温增加, 产量减少幅度大于133 kg·hm–2的概率增加16%, 产量增加超过137 kg·hm–2的发生概率减少10%。随着极端最高气温增加, 产量减少幅度大于133 kg·hm–2的概率和产量增加超过137 kg·hm–2的发生概率则分别增加17%和减少12%。综上所述, 1990—2019年新疆棉花产量呈增加趋势。棉花减产的概率随着极端最低气温和极端最高气温的增加逐渐增加。本研究明确了棉花产量发生概率对极端气候指标的响应, 有利于规避棉花生产风险, 帮助制定生产策略, 促进棉花产业发展适应气候变化。Abstract: Extreme temperature events are becoming increasingly frequent due to global warming. This poses a serious threat to the crop production. Cotton is an important cash crop in China, and Xinjiang accounts for 20% of the global cotton production. Studying the effects of extreme temperatures on cotton yields is important for developing the Chinese cotton industry. In this study, we used the Mann-Kendall trend test and Sens slope method to analyze the spatial and temporal characteristics of yield variation and assessed the response of cotton yield to temperature extremes using the copula function based on historical climate data and cotton yield data in Xinjiang from 1990 to 2019. The results show that the upward trend in cotton yield from 1990 to 2019 was highly significant (P<0.01) in 86% of Xinjiang. The probability of an increase in cotton production because of extreme temperature effects was greater than 20% in 41.7% of the southern border but only 26.1% of the northern border. The probability of cotton yield reduction because of extreme temperatures was less than 30% in 92.6% of the areas across Xinjiang, and areas with a probability of yield reduction greater than 30% were concentrated north of the Tianshan Mountains. The cotton climatic yield was significantly affected by the minimum daily temperature during the cotton growth period and the maximum daily temperature during the cotton growth period among the six extreme climate indicators. The probability of a yield reduction of more than 133 kg·hm–2 increased by 16%, and the probability of a yield increase of more than 137 kg·hm–2 decreased by 10% as the minimum daily temperature during the cotton growth period increased, but increased by 17% and decreased by 12% as the maximum daily temperature during the cotton growth period increased. This study demonstrates that cotton production in Xinjiang exhibited an upward trend from 1990 to 2019. The likelihood of a negative impact on cotton yield increases with increases in the minimum daily minimum temperature during the cotton growth period and maximum daily maximum temperature for the cotton growth period. It is beneficial to reduce the risks associated with cotton production, establish production plans, and encourage the growth of the cotton industry’s ability to adapt to climate change to clarify how cotton yield occurrence probability responds to extreme climate indicators.