Spatiotemporal dynamics and future scenario simulation of farmland carbon sources and sinks patterns in the Guanzhong region, China

Abstract Farmland ecosystems play a vital role in regional carbon cycling and are strongly influenced by climate variability and agricultural management.The Guanzhong region, a major agricultural area in northwestern China, is characterized by an intensive winter wheat–summer maize rotation and widespread irrigation.A refined assessment of cropland net ecosystem productivity(NEP) and its driving factors is therefore important for understanding the spatial heterogeneity of carbon sink capacity and for formulating carbon sequestration strategies.Accordingly, this study integrated multi-source datasets with an improved CASA model and a soil heterotrophic respiration model to estimate farmland NEP from 2000 to 2023.Trend, stability, and Pearson correlation analysis were used to investigate the spatiotemporal variation and management-related associations of NEP, while CMIP6 climate projections were used to simulate future NEP under the SSP126,SSP245,and SSP585 scenarios for 2030,2045,and 2060.The results showed that farmland NEP exhibited a fluctuating upward trend during 2000–2023,with a spatial pattern characterized by higher values in the west and lower values in the east.Human-related factors, including straw returning area, fertilizer application rate, and agricultural machinery power, generally enhanced farmland NEP, whereas excessive multiple cropping and improper irrigation exerted negative effects on NEP in certain areas; under future warming and wetting conditions, farmland NEP in the Guanzhong region is projected to decline overall, and the extent of carbon sink conservation areas is expected to decrease relative to the historical period.The findings provide scientific support for optimizing agricultural management, enhancing farmland carbon sequestration, and promoting sustainable agricultural development in the Guanzhong region.