Author(s): Sida Li; Dongdong Shao
Linked Author(s): Dongdong Shao
Keywords: Megafauna reintroduction hydrological regime shift vegetation dynamics floodplain wetlands
Abstract: Megafauna reintroduction is increasingly considered as an option for ecological restoration and can profoundly impact the recipient vegetation communities. Yet it remains unclear how these initiatives influence vegetation communities in floodplain wetlands, particularly when combined with concurrent hydrological regime shift. In this study, the joint impact of reintroduced megafauna and hydrological regime shift on the distribution and growth of floodplain vegetation communities were evaluated using decadal observational data collected at the Milu (Elaphurus davidianus) reintroduction floodplain site in Hubei Shishou Milu National Nature Reserve, China. Firstly, the training sample migration method and random forest classifier were applied to time-series Landsat images to produce annual 30 m vegetation maps of the study area during 1993-2023. These maps consisted of waterbody and four types of vegetation community with varying adaption to hydrological regime shift: Carex spp. (hygrophyte), Phragmites australis (hygrophyte), Xanthium mongolicum (xerophyte), and forest. Secondly, time-series annual maximum NDVI of each vegetation type were calculated as an indicator to represent growth status. Finally, annual variation in Milu population and three hydrological indices, i. e., inundation depth, frequency and duration, were collected to assess their combined effects on vegetation dynamics through the generalized linear mixed model (GLMM). The results showed that vegetation communities with varying adaptation to hydrological regime shift responded differently to megafauna reintroduction. Milu reintroduction and their population expansion reduced the growth of hygrophytes, which was magnified by the decreasing duration and frequency of floodplain inundation. The hydrological regime shift had a more profound impact on the distribution of vegetation communities, where the reduction in duration and frequency of floodplain inundation is the best predictor of the increase in cover of xerophytes. Our findings illustrate a distinctive response of floodplain vegetation communities to reintroduced megafauna, and these responses were mediated by hydrological regime shift. These findings deepen our understanding of the ecological consequence of megafauna reintroduction in floodplain wetlands, and have important implications for the management of these initiatives under growing environmental changes.
Year: 2025