气候变化对东北地区大豆种植气候适宜性影响

The Impact of Climate Change on Climate Suitability for Soybean Planting in Northeast China

  • 摘要: 大豆是我国重要的粮油作物,扩大大豆种植面积和提高大豆产量对我国粮食安全具有重要意义。利用1961—2023年黑龙江、吉林、辽宁、内蒙古东部气象站逐日气象数据、东北地区部分县级大豆单产数据以及LightGBM模型,研究气候变化对东北地区大豆种植气候适宜性影响。结果表明:1961—2023年东北地区大豆生长季平均气温升温速率为0.25 ℃·(10 a)-1,主要变暖时段为1991—2023年,2014—2023年大豆开花期低温日数较20世纪60年代减少45.4%,东北地区热量资源明显改善。大豆生长季降水量波动较大,干旱日数无明显变化。利用1961—1990年、1991—2020年和2014—2023年气候因子和气象灾害数据驱动LightGBM模型,研究显示受气候变暖影响,东北地区大豆种植气候较适宜区明显向西向北扩大,大豆种植不适宜区明显缩小。1961—1990年大豆种植较适宜区的气象站数量占研究区域气象站数量的90%,1991—2020年占比增加至95%,2014—2023年占比增加至96%。

     

    Abstract: To investigate the impact of climate change on the climate suitability for soybean cultivation in Northeast China, daily meteorological data from 1961 to 2023, county-level soybean yield data from 1993 to 2022 and LightGBM model are used to study changes in climate conditions, drought and low temperature, as well as their comprehensive effects on the climate suitability for soybean cultivation. As a result of global warming, heat resources in Northeast China have significantly improved, and characteristics of disasters also change obviously. The average temperature during the growing period of soybeans in Northeast China shows a significant increasing trend, with an average temperature rise rate of 0.25 ℃·(10 a)-1 from 1961 to 2023. The accumulated temperature reached 2884.9 ℃·d from 2021 to 2023, with an increase of 8.8% compared to the 1970s. The fluctuation in precipitation during the growth period of soybeans in Northeast China has increased, while the number of sunshine hours has decreased. The number of low-temperature days during soybean flowering shows a significant decreasing trend, with a reduction of 45.4% during 2014-2023 compared to the 1960s. There is no increasing trend in the number of drought days during the soybean growing period in Northeast China. LightGBM model is trained and utilized to identify climate suitability parameters for soybean cultivation in Northeast China. Soybean yields exhibit a negative correlation with the number of drought days during the growing period and the number of low-temperature days during the flowering stage. The correlation coefficient between soybean yield and the number of low-temperature days during the growing period of soybean is -0.23 (passing the test of 0.01 level). The yield of soybeans is positively correlated with accumulated temperatures (no less than 10 ℃) and the monthly average temperatures from May to September. In order to train the model, samples are divided into training and testing sets, with 80% of data allocated to the training dataset and the remaining 20% designated as the testing dataset. The correlation coefficient between the predicted index and the actual index in the model training set is 0.94 (passing the test of 0.01 level). The correlation coefficient between the predicted index and the actual index in the test set is 0.80 (passing the test of 0.01 level). This study utilized annual climate data from 1961 to 1990, 1991 to 2020, and 2014 to 2023 to drive the LightGBM model and calculate the changes in climate suitability indices for soybean cultivation. It demonstrates that, as a result of climate warming, areas suitable for soybean cultivation in Northeast China have significantly expanded to the west and the north. Suitable soybean planting sites comprised 90% of the total research sites from 1961 to 1990, and this figure increased to 95% of sites from 1991 to 2020.

     

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