Simulating Dynamic Vegetation Changes in a Tidal Restriction Area with Relative Stress Tolerance Curves

Abstract

After tidal restriction in salt marshes, the composition of the vegetation changes from predominance of halophyte species to predominance of glycophytes. However, little is known about how different plant traits and stress types influence these vegetation changes. In this study, we propose the use of relative stress tolerance curves to couple stress tolerance and competitive abilities in a dynamic vegetation model. This model overcomes the difficulties of 1) accounting for variations in interspecific interactions with changes in the hydrological regime, and 2) simulating vegetation dynamics in response to continuously changing stress levels in the tidal restriction region. The model was applied to the tidal restriction area of the Yellow River Delta. Key determinants for altered species abundance of Phragmites australis and Tamarix chinensis were interspecific competitive abilities and waterlogging stress, respectively. Waterlogging stress and interspecific competitive ability under soil salinity stress were key determinants for altered Suaeda glauca abundance. Analysis of multiple scenarios revealed that the simulated plant community is hysteretic to changes in the hydrological regime. The structure of the simulated plant community was constant in the first 4 years after tidal reintroduction due to hysteretic effects, but recovered rapidly thereafter. To achieve efficient restoration effects of a plant community, a rapid alteration of the hydrological regime is recommended to decrease the extent of hysteresis effects.