Comprehending the spatiotemporal dynamics, spatial heterogeneity, and pattern-process relationships of small and micro wetlands (SMWs) holds paramount significance for their conservation, restoration, and sustainable management. We integrated Landsat imagery, land-use, topographic, climatic, socioeconomic, and statistical data for 1990–2020 in Anhui Province. Random forest classification, kernel density estimation, standard deviation ellipses, centroid migration, landscape metrics, land-use transition analysis, ecosystem service value (ESV) assessment, and Geodetector were used to characterize SMW change. Total SMW area increased from 53,843.67 ha in 1990 to 71,637.39 ha in 2020, while patch number increased from 104,011 to 125,971; patches smaller than 3 hm² remained dominant. High-density areas were concentrated in the Jianghuai Plain, Yangtze River plain, Chaohu Lake region, and agricultural drainage networks, with a persistent northeast–southwest distribution orientation. Land-use transitions were dominated by exchanges among cropland, water bodies, and SMWs. At constant 2020 grain prices, total ESV increased from approximately CNY 3.668 billion in 1990 to CNY 6.840 billion in 2020, with hydrological regulation remaining among the largest service components. Geodetector results showed temporally varying single-factor spatial associations, while interaction patterns suggested potential joint spatial associations among natural and anthropogenic factors. These results support spatially targeted SMW conservation and management in Anhui Province.

Mangroves are critical components of coastal wetland ecosystems, providing essential services such as high-capacity carbon sequestration, biodiversity conservation, and shoreline protection. They play an irreplaceable role in mitigating climate change and maintaining coastal ecological balance. However, the effects of S. alterniflora management on mangrove carbon sinks in coastal wetlands remain poorly quantified, particularly with respect to canopy structural constraints. To address this issue, this study took the Zhangjiang Estuary Mangrove National Nature Reserve in Fujian Province as the study area and constructed a retrieval framework for mangrove above-ground vegetation carbon stock integrating Sentinel-1/2 multi-source remote sensing and ICESat-2 spaceborne LiDAR data. Based on the 10-year time series data from 2016 to 2025, we analyzed the spatiotemporal evolution patterns of mangroves and S. alterniflora. Mangrove area was calculated by counting valid mangrove pixels from 10-m annual land-cover maps generated by the accuracy-validated Random Forest classifier, with pixel area used for areal conversion. We further selected three key years (2021, 2023, and 2025) to explore the phased-variation characteristics of mangrove canopy height and above-ground vegetation carbon stock. The results showed that: (1) the mangrove area in Zhangjiang Estuary increased significantly from 2016 to 2025, with two phases, namely stable at 75.78–81.34 ha (2016–2022) and rapid growth to 183.49 ha by 2025, which is consistent with the expected outcomes of local conservation and restoration practices; (2) mangrove canopy height was retrieved using the random forest model, with a coefficient of determination R² of 0.75 and a root mean square error (RMSE) of 0.92 m, which reliably characterized the spatial distribution patterns of mangrove canopy height in the study area; and (3) from 2021 to 2025, S. alterniflora coverage dropped by more than 98%, while mangrove carbon storage rose 118.3% and vegetation expanded outward to tidal flats. The enhancement of mangrove carbon sink function was highly consistent with the implementation progress of S. alterniflora governance and associated mangrove restoration practices. The results of this study provide a scientific basis for evaluating invasive alien species management outcomes, guiding mangrove ecological restoration, and optimizing blue carbon resource management in coastal wetland ecosystems.