Vegetation dynamics under water-level fluctuations: Implications for wetland restoration

Abstract

Hydrological regimes play a vital role in regulating wetland structure and function, regarded as fundamental for wetland protection and restoration. This study explored vegetation response to water-level dynamics, simulated vegetation patterns, and the estimated evapotranspiration (ET) pertaining to different hydrological statuses. We used the vegetation dynamics simulation model and topography- and vegetation-based surface energy partitioning algorithms (TVET model) designed to estimate potential evaporation (PE) and potential transpiration (PT). Results indicated that: (i) Vegetation cover and water levels of different hydrological statuses can be used to deduce suitable water levels during flood, normal, and drought statuses (which were 1.23, 0.99, and 0.81 m, respectively, in the Ertou wetland). (ii) Dynamic vegetation simulations combined with optimal ecological water levels for Phragmites australis and Bolboschoenus planiculmis sustenance can be used to simulate vegetation pattern dynamics. Both P. australis and B. planiculmis expanded during droughts along with a reduction in open water, providing a potential increase in food availability for Siberian crane (Grus leucogeranus). (iii) Changes in vegetation patterns and characteristics (e.g., plant height and leaf area index (LAI)) that varied with water-level fluctuations inevitably altered potential evapotranspiration (PET) partitioning into PE and PT. These results indicate that subtle water-level fluctuations can dramatically alter vegetation patterns, characteristics, and ecological processes, subsequently affecting shallow wetland habitats. Further investigations are necessary to clarify wetland coupling mechanisms between hydrology, vegetation, and habitat. This will help address extreme drought and flooding events while also helping to assess wetland protection and restoration.