基于改进鲸鱼优化算法的种植业碳排放预测

Prediction of carbon emissions from the planting industry based on the improved whale optimization algorithm

  • 摘要: 种植业碳排放是温室气体排放的重要来源之一, 对其进行准确预测与有效管理能够减缓气候变化和推动农业可持续发展。传统预测模型难以捕捉种植业碳排放系统中复杂的非线性关系, 且模型鲁棒性不足, 易引发过拟合。为了优化现有种植业碳排放预测方法, 本研究以黑龙江省为例, 开展种植业碳排放预测研究。首先, 采用联合国政府间气候变化专门委员会(IPCC)碳排放系数法, 综合考虑农地利用碳排放、稻田CH4排放和农地N2O排放, 对2001—2022年黑龙江省种植业碳排放量进行系统测算。在此基础上, 构建涵盖社会经济驱动、生产规模效应和技术能耗强度3个维度的长短期记忆网络(LSTM)模型, 并引入改进鲸鱼优化算法(IWOA)对LSTM模型的隐藏单元数、学习率、批量大小和训练轮次4个超参数进行优化, 以提升模型的预测性能。最后, 利用IWOA-LSTM模型预测了基准情景和低碳情景下2023—2027年黑龙江省种植业碳排放。研究结果显示: 1)黑龙江省种植业碳排放量呈“先快速增长后波动下降”的趋势, 2015年达到峰值(2 045.28万t)。主要的碳排放源包括稻田CH4排放、农地N2O排放以及化肥生产和施用导致的碳排放, 年平均占比分别为41.42%、38.26%和11.65%。2)与未经优化的LSTM模型相比, IWOA-LSTM模型在预测准确性和稳定性方面均有显著提升, 其平均绝对误差为55.82万t, 均方根误差为61.74万t, 平均绝对百分比误差为2.83%, 分别低于LSTM模型的114.41万t、124.72万t和5.78%。3)采用IWOA-LSTM模型, 对2023—2027年黑龙江省种植业基准情景和低碳情景碳排放预测的结果显示, 通过控制农作物种植面积、提升化肥施用效率以及减少单位面积农机柴油消耗量, 能够有效抑制黑龙江省种植业的碳排放增长。

     

    Abstract: Carbon emissions from the planting industry are a significant source of greenhouse gas emissions. The accurate prediction and effective management of these emissions are crucial for mitigating climate change and promoting sustainable agricultural development. Conventional prediction models exhibit a limited capability to capture the complex nonlinear interactions inherent in carbon emission systems of the planting industry, and their insufficient robustness often leads to overfitting. In this study, we used the planting industry in Heilongjiang Province as a case study to explore how to optimize existing methods for predicting carbon emissions from the planting industry. First, the IPCC carbon emission method is applied to comprehensively account for three major sources of carbon emissions: carbon emissions from agricultural land use, CH4 emissions from rice field, and N2O emissions from agricultural land. Carbon emissions from planting activities in Heilongjiang Province from 2001 to 2022 were systematically calculated. Based on this, a long short-term memory (LSTM) network model was developed, incorporating three key dimensions: social and economic drivers, production scale effects, and technical energy consumption intensity. To enhance the predictive performance of the model, an improved whale optimization algorithm (IWOA) was introduced to optimize four hyperparameters of the LSTM model: number of hidden units, learning rate, batch size, and training epochs. Then, the IWOA-LSTM model was used to predict future carbon emissions from the planting industry in Heilongjiang Province from 2023 to 2027 under both baseline and low-carbon scenarios. The results were showed as below. 1) Carbon emissions from the planting industry in Heilongjiang Province showed a trend of “rapid growth followed by a fluctuating decline”, reaching a peak of 20.45 million t in 2015. The main sources of carbon emissions included CH4 emissions from rice field, N2O emissions from agricultural land, and carbon emissions resulting from fertilizer production and application; their average proportions in the total annual emissions were 41.42%, 38.26%, and 11.65%, respectively. 2) Compared with the unoptimized LSTM model, the IWOA-LSTM model demonstrated significant improvements in both the prediction accuracy and stability. It achieved a mean absolute error of 55.82×104 t, root mean square error of 61.74×104 t, and mean absolute percentage error of 2.83%, all of which were superior to those of the LSTM model (114.41×104 t, 124.72×104 t, and 5.78%). In this study, we demonstrated that the IWOA-LSTM model could effectively predict carbon emissions from the planting industry, thereby providing a scientific basis for the formulation of carbon reduction policies for the planting industry in Heilongjiang Province. 3) The prediction results of the IWOA-LSTM model showed that carbon emissions from the planting industry in Heilongjiang Province could be effectively suppressed by controlling the crop planting area, improving fertilizer application efficiency, and reducing diesel consumption per unit area of agricultural machinery. Based on the aforementioned conclusions, the following recommendations for emission reduction are proposed: optimizing land-use structure and controlling crop planting area, increasing the application and innovation of green agricultural technologies, promoting rural economic development, increasing farmers’ income, and strengthening policy support and incentive mechanisms. Through the above measures, the sustainable development of agriculture in Heilongjiang Province can be further achieved.

     

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