Spatiotemporal Differentiation of Land Carbon Metabolism in the Shiyang River Basin of China: An Ecological Network Utility Perspective

Revealing the spatiotemporal evolution patterns and driving factors of carbon metabolism in arid inland river basins is critical for ecological governance, environmental protection, and low-carbon sustainable development policy formulation. This study aims to answer two core scientific questions: 1) how do land use transitions alter the spatiotemporal patterns of regional carbon emissions and carbon sequestration, and what are the characteristics of carbon transfer between different land-use types? 2) What ecological interaction relationships exist among various land-use compartments within the carbon metabolism network, and which factors dominate the spatial heterogeneity of carbon metabolism? Taking the Shiyang River Basin (SRB) of China as the study area, we evaluated the impacts of land use and land cover change on carbon metabolism during 2000–2020 using Ecological Network Analysis (ENA) and adopted the Optimal Parameter-based Geographical Detector (OPGD) model to quantify the individual impacts and interactive effects of multiple drivers. The results show that: 1) from 2000 to 2020, carbon emissions in the SRB maintained a steady upward trend and peaked in 2010; transportation and industrial land served as the dominant emission source, accounting for 48.83% of total emissions. The basin’s carbon balance deteriorated modestly, while carbon sequestration capacity increased only slightly, resulting in persistent negative net carbon flow. 2) The average mutualism index across the basin reached 0.67, indicating that competition among various land-use types constituted the primary ecological relationship, and land use and land cover change exerted overall adverse impacts on regional carbon metabolism. 3) Vegetation type, normalized difference vegetation index (NDVI), and population density were the key determinants of carbon metabolism, and the synergistic effect between NDVI and vegetation type was the strongest. On this basis, this study discusses the complex coupling relationships among land use and land cover change, carbon transfer, and regional carbon metabolism in arid inland river basins. The findings and methodological framework proposed in this paper can provide theoretical references and decision-making suggestions for regional climate change mitigation and low-carbon development.