Faster autumn recession and increased abundance of Geese after 2003 in Poyang Lake: Temporal cascading effects from water to mudflats and grasslands

Study Region Poyang Lake, a river-connected floodplain lake in the middle and lower Yangtze River, is a major wintering area for Greater White-fronted Geese ( Anser albifrons ) along the East Asian–Australasian Flyway. Study Focus We examined how post-2003 changes in autumn recession affected goose abundance and habitat formation. Goose surveys (1998–2022), daily water levels, generalized additive models, EFDC inundation–exposure simulations, and Hill-type Logistic analysis were combined to identify hydrologically sensitive stages, characterize habitat cascade transformation, and determine the hydrological opportunity window. New Hydrological Insights for the Region Under Study After 2003, water levels below 10 m occurred 28 d earlier and persisted 45 d longer. Goose abundance was associated with October water level and November recession rate, with responses concentrated during September–November. Earlier recession propagated through the water–mudflat–grassland cascade, advancing sparse-grassland formation during early recession but reducing its persistence later. The principal rapid-expansion range narrowed from approximately 9.5–12.0 m to 10.0–11.5 m, while EC(50) remained near 10.7 m. This narrowing was consistent across alternative percentile bounds, with the post-2003 interval approximately 40% narrower. The 10.0–11.5 m range therefore defines a multi-year hydrological opportunity window under post-2003 mean conditions and provides a quantitative basis for linking autumn recession, habitat formation, and goose response.