Adjusting the Main Cropping Types in Mollisol Regions Could Improve the Net Primary Productivity of Low-Producing Areas by 20%–30% Under Future Climate Change

Abstract

Rationalizing site-specific crop types is an effective strategy for ensuring food security under climate change. This study employed environmental covariates representing climate, soil, and vegetation, combined with a hybrid convolutional neural network - Long Short-term Memory-self-attention (CNN-LSTM-SA) model to predict net primary productivity (NPP) of the Northeast China (NEC) and the Mississippi River Basin (MRB) Mollisol regions. The analysis covered the periods from 2001 to 2020, and 2021 to 2040 under two Shared Socioeconomic Pathways (SSPs): SSP245 and SSP585. Subsequently, areas requiring crop type adjustments were identified, and appropriate crops were assigned to each growth site. Our results elucidate that: (a) During 2021–2040, a general increase in temperature and minor fluctuations in precipitation were observed across the study area. In the NEC, crop NPP initially increases before decreasing, whereas in the MRB, it consistently decreases. (b) Both vegetation and soil covariates explained 75.6% of NPP variability in the NEC, while in the MRB, climate factors, particularly precipitation, accounted for 18.4% of the variability. (c) The proportion of area requiring adjustment in the NEC ranged from 4.45% to 5.13% (SSP245) to 5.05%–5.77% (SSP585), while in the MRB, it varied from 4.92% to 7.54% (SSP245) to 6.49%–9.10% (SSP585), suggesting a necessity for more substantial cropping type adjustments under the SSP585 climate scenario. (d) In the NEC, the area cultivated with corn, soybean, and other crops will decrease, while rice cultivation will increase. Conversely, a decrease in wheat and pasture, and an increase in corn and soybean cultivation are suggested in the MRB. (e) Following crop type adjustments, the average NPP enhancements for corn, soybean, rice, and other crops in unsuitable areas of the NEC were 22.85%, 22.2%, 17.35%, and 20.5%, respectively, In the MRB, the average NPP enhancements for corn, soybean, wheat, and pasture were 28.5%, 26.9%, 32.4%, and 21.1%, respectively. Our research provides valuable insights into predicting future NPP changes, and develops effective crop adjustment strategies to address global food security challenges.