Quantifying responses of net primary productivity to agricultural expansion in drylands

There is a limited understanding of agricultural land dynamics across global drylands and the impacts of transitions between agricultural land and land cover on net primary productivity (NPP) changes. This study attempted to fill this gap by examining agricultural land changes and NPP responses in drylands. A data-driven assessment of effects on the NPP of individual agricultural land displacement was carried out using three methods: the mean difference method, a newly introduced ridge-regression method, and a proposed method based on actual change excluding climate impact. Increases in NPP were accompanied by agricultural land transitions from natural land cover and expected forests. The agricultural expansion mainly replaced sparse vegetation and grassland and increased the overall NPP of the dryland ecosystem. The mean difference method and ridge-regression method overestimated the NPP increase caused by agricultural land expansion. Land use change contributed more than 70% to NPP increase in the new agricultural area. However, land use change has less effect on total NPP in drylands than climate change. Monitoring agricultural land dynamics and distinguishing NPP changes caused by different agricultural land transitions is helpful for targeted management and sustainable development of agriculture in drylands.

Automated summary

This study found that agricultural land expansion in drylands has a significant impact on increasing NPP, but less compared to the impact of climate change. Agricultural expansion mainly replaced sparse vegetation and grassland, leading to an overall increase in NPP in dryland ecosystems.