Ecological network optimization and its correlation with net primary productivity in the Thal Desert: a 20-year analysis

The growing threats of land degradation, climatic unpredictability, and habitat fragmentation present significant challenges to ecosystems, particularly in arid and semi-arid regions such as the Thal Desert in Punjab, Pakistan. This study applies an integrated ecological network optimization framework, combining Minimum Cumulative Resistance (MCR), Revised Universal Soil Loss Equation (RUSLE), and advanced regression modeling to evaluate the relationship between soil conservation, ecological connectivity, and Net Primary Productivity (NPP) trends from 2001 to 2021. The analysis investigates how changes in network structure (e.g. connectivity and centrality) and soil conservation capacity correlate with NPP trends, offering insights into the role of network optimization in supporting ecosystem resilience. Results indicate a significant ninefold increase in windbreak and sand-fixation capacity, from 2.6×10¹¹ in 2001 to 2.37×10¹² in 2021, largely due to afforestation and reforestation efforts in the central and northeastern regions. Soil conservation capacity rose from approximately 302,000 tons to nearly 3.85 million tons, despite spatial heterogeneity and the localized impacts of water scarcity. NPP peaked at 79.84g·m⁻²·a⁻¹ in 2011 but sharply declined to 12.85g·m⁻²·a⁻¹ by 2021, with grasslands showing the steepest decline in productivity, from 400 gC/m²·yr to 320 gC/m²·yr. Ecological network analysis identified over 320 corridors, with forest and shrubland patches acting as key connectivity hubs. Topological metrics revealed increased centralization and modularity, with node 151’s betweenness centrality more than doubling from 0.07 to 0.15, indicating improved network resilience. Regression models, particularly the exponential and power functions, effectively captured the nonlinear relationship between NPP and connectivity, with eigenvector centrality showing strong positive correlations (r>0.78) across all years. These findings highlight the critical role of ecological network optimization in enhancing carbon sequestration, connectivity, and ecosystem resilience in arid landscapes affected by climate change, providing valuable insights for targeted conservation and adaptive management strategies.