Agriculture-conservation nexus in East Asian GIAHS: Paddy reclamation reshapes migratory avian communities

Existing studies suggest that land use/land cover (LULC) changes causing biodiversity loss have inadequately incorporated the sustainability paradigm of human-nature coupled systems in East Asian Globally Important Agricultural Heritage Systems (GIAHS), while also lacking analysis of differential responses among specific species to cultivated landscape changes. Based on the theoretical framework of human-nature coupled systems, this study reveals the compound ecological effects of paddy field reclamation policies in East Asian agricultural heritage sites. Focusing on China's Liaohe river wetlands, one of the world's fastest-changing estuarine ecosystems in land cover, we integrated multi-source remote sensing data and avian biodiversity data from 1990 to 2023 to quantitatively assess the response patterns between paddy reclamation and bird biodiversity. Results show that paddy field coverage in the Liaohe river wetlands increased from 29.79% to 45.25%, primarily driven by rice-crab symbiotic system expansion. However, this ecological compatibility did not significantly reduce net potential biodiversity loss, but rather altered avian community structures, consequently influencing the typological and functional choices of global migratory birds. This indicates that agricultural land changes in heritage sites can enhance avian diversity and stability by creating eco-mimetic habitats and food supplies, effectively substituting natural wetland functions, while simultaneously reshaping biological chains at typological scales. These findings challenge the unidirectional ecological loss assumptions in LULC changes, provide critical empirical evidence for aligning the Kunming-Montreal Global Biodiversity Framework with Globally Important Agricultural Heritage Systems conservation goals, and establish a novel land-sharing pathway for synergistic agricultural intensification and ecological protection.