Agricultural Climatic Factors and Their Thresholds for Winter Wheat Cultivation in Northern China
[Background]To determine the safe planting limit of winter wheat based on agricultural climate indicators is crucial for the scientific and rational utilization of resources,avoiding freezing disasters,and ensuring stable and high yields of winter wheat.However,in the north of China,which is located in the sensitive area of winter wheat planting,the fluctuation of safe winter wheat planting has been intensified due to the increase of extreme weather events caused by global climate change.It is urgent to clarify the agroclimatic factors affecting the safe planting of winter wheat on a large regional scale and to determine their threshold ranges.[Objective]The research on the agricultural climatic factors and their thresholds for the safe planting of winter wheat was conducted to provide a scientific basis for the sustainable production and planning of winter wheat in response to climate change.[Method]The northern China was selected as the research area,which was highly sensitive to the safe planting of winter wheat.Based on the spatial distribution of winter wheat with medium and high spatial resolution and ground meteorological observation data,this research utilized methods such as kernel density estimation,geographic detector to reveal the spatial pattern characteristics of the actual northern limit of winter wheat planting,to quantitatively analyze the influence of agricultural climate factors on the formation of the actual northern limit of winter wheat planting,and to explore the threshold of key climate factors.[Result](1)The actual northern limit of winter wheat planting,with a total length of about 2 200 km,fluctuated from southwest to northeast.However,agricultural climate factors exhibited more significant fluctuations along the line of Pingning-Xunyi-Tongchuan-Baishui-Heyang-Hancheng-Jishan.(2)The negative accumulative temperature during winter,average temperature of the coldest month,extreme minimum temperature of the year,and accumulative temperature before winter were crucial factors(q＞0.45)in shaping the actual northern limit of winter wheat planting.Agricultural precipitation factors had a minor effect(q＜0.19)on winter wheat planting,but interacted strongly with temperature factors(q＞0.57).(3)Specific meteorological parameters for the northern limit of winter wheat safe planting in northern China were established:negative accumulated temperature in overwintering period ≥-620℃·d,coldest monthly mean temperature≥-8 ℃,annual extreme minimum temperature≥-22 ℃,and accumulated temperature before overwintering ≥529 ℃·d.(4)The potential northern limit for winter wheat planting has moved about 107 km northward compared to the actual limit,with approximately 23.39 × 103 km2 of expansion area.[Conclusion]This study identified the key agricultural climate indicators and thresholds influencing safe winter wheat planting in northern China,which provided a basis for determining potential safe planting areas for winter wheat.The research results could provide the theoretical reference and technical support for how winter wheat planting could adapt to climate change and adjust agricultural planting layout reasonably.
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