Simulation of wetland vegetation succession based on coupled Gaussian and population dynamics models: A case study of Poyang Lake wetlands

Wetland vegetation is the most crucial primary producer in wetland ecosystems and serves as an indicator of ecosystem health. After 2003, significant changes occurred in the “river-lake relationship” between Poyang Lake and the Yangtze River, with intensified dry conditions in autumn and winter leading to a shortened inundation period for sandbanks and significant changes in the community structure and spatial distribution of wetland vegetation. By coupling a Gaussian model with a population dynamics model, this study simulated the response of wetland vegetation to inundation duration under different hydrological year types, revealing the relationship between vegetation distribution and inundation duration. Key parameters, such as growth and mortality rates, were identified, and the vegetation succession and spatial distribution of Poyang Lake wetlands were simulated for five representative years: a wet year (2010), a normal year (2001), a dry year (2006), an extreme wet year (1998), and an extreme dry year (2022). The results showed that the response of wetland vegetation to inundation duration followed a Gaussian curve, with each species exhibiting an optimal range of inundation durations. Mortality rates increased when the duration fell outside this range. In 2010, the total area of wetland vegetation was similar to that in a normal year, but the proportions of different plant species varied significantly. Compared to 2001, the areas of Phalaris arundinacea and Polygonum criopolitanum increased by 50.92 % and 24.86 %, respectively, while the areas of Phragmites australis and Triarrhena lutarioriparia decreased by 71.66 % and 83.49 %. In 1998, the total vegetation area shrank considerably, with a 54.74 % reduction compared to 2001 and a 64.32 % reduction compared to 2006. In contrast, the total wetland vegetation area reached its maximum in the extreme dry year of 2022, increasing by 41.35 % compared to 2001. Among dominant species, Carex spp., Cynodon dactylon, and Phragmites australis expanded significantly in dry years, while Phalaris arundinacea and Polygonum criopolitanum were better adapted to flood conditions.