Process-dependent wetland degradation and ecological resilience in Northeast China revealed by a zone-weighted regional wetland composite index

In Northeast China, wetland degradation has intensified under climate change and human activities, disturbing the stability of the system. However, due to the spatial heterogeneity in dominant degradation processes, the applicability of conventional indicators and fixed weighting schemes appears to be limited. To address this issue, this study developed a dominant-process-based zonal weighting framework by distinguishing wetlands in Northeast China into a salinization-dominated zone (SDZ) and a hydrology-dominated zone (HDZ), and constructed a zone-weighted Regional Wetland Composite Index (RWCI). Moreover, environmental and socioeconomic factors were analyzed in relation to long-term mean RWCI. The results show that RWCI effectively characterized wetland habitat changes (POA = 91.65%, Kappa = 0.9008). During 2000–2023, increasing RWCI trends were observed in 69.73% of the baseline wetland pixels in the SDZ, whereas decreasing trends occurred in 50.28% of the pixels in the HDZ. Low and medium resilience wetlands of 54.76% and 41.17%, respectively suggesting the recovery trend in partial regions, while the ecosystem stability was still insufficient. Moreover, the driving contributions also differed between zones. In the SDZ, long-term mean RWCI was mainly associated with hydrothermal factors, especially precipitation (33.2%). Conversely, long-term mean RWCI in the HDZ was more strongly associated with human activity, especially population density (26.3%). Overall, this paper indicates the regional heterogeneity of wetlands in degradation, stability risk and their drivers, offering scientific support for zoned management, risk warning and wetland conservation in Northeast China.