Wetland Loss Offsets Climate Change Benefits on Ecological Security Network in Songnen Plain, Northeast China

A robust ecological security network (ESN) is essential for ensuring regional ecological security, improving fragile ecological conditions, and promoting sustainable development. Climate change and land use/cover change (LUCC) influence the structure and connectivity of the ESN by impacting ecosystem services (ESs). Previous studies primarily focused on the overall effects of LUCC on ESN changes, but they largely overlooked the effects of detailed LUCC transitions. In this study, we evaluated changes in the structure and connectivity of the ESN in the Songnen Plain (SNP), Northeast China, over the past 30 yr (1990s-2020s) using circuit theory and graph theory. We further explored the effects of climate change, LUCC, and detailed LUCC transformations on ESN changes through factorial control experiments. Results revealed a 24.86% decrease in ecological sources and a 27.06% decrease in ecological corridors, accompanied by a decline in ESN connectivity from the 1990s to the 2010s. Conversely, from the 2010s to the 2020s, ecological sources increased by 14.71% and ecological corridors increased by 25.71% due to ecological projects such as returning farmland to wetlands, resulting in an overall increase in ESN connectivity. The changes in ESN structure were primarily attributed to LUCC effects, followed by climate change effects and their interactions. In contrast, the changes in connectivity were significantly affected by climate change, followed by interactive effects and LUCC. Through detailed examination of LUCC transformation effects, we further found that the changes in ESN structure were primarily attributed to wetland loss, followed by deforestation and urban expansion. Meanwhile, the changes in ESN connectivity were mainly due to the effects of wetland loss, urban expansion and deforestation. Notably, the adverse effects of wetland loss partly offset climate change benefits on ESN. Our study offers valuable insights for developing future land management policies and implementing ecological projects, aimed at maintaining a stable ESN and ensuring sustainable human development.