Plant community structures and species diversity of the Nanwan Lake riparian zone within Xinyang city in winter

In the winter of 2023， 12 plots were established within the riparian zone of Nanwan Lake in Xinyang city， for investigating and analyzing the plant composition， distribution， and species diversity. Regression analysis and detrended correspondence analysis （DCA） were also used to examine the impact of disturbance levels and invasive alien species on the plant community in riparian zone. The results showed that： ① A total of 40 plant species belonging to 15 families and 32 genera were recorded in the 12 plots， with high species richness in the Compositae， Gramineae， Cyperaceae， and Rosaceae. The dominant species with a total importance value >0.5 were Alternanthera philoxeroides， Phragmites australis， Erigeron annuus， Ranunculus sceleratus， Geranium carolinianum， and Erigeron sumatrensis， and the invasive plants formed dense single-dominant communities. ② The average values of the Patrick index， Shannon-Wiener index， Simpson index， and Pielou index for the plant community were 7.083， 1.643， 0.758， and 0.860， respectively. The coefficients of variation for all these four indices were between 0.1 and 1.0. Moderate human disturbance could help increase plant diversity， while the A. philoxeroides invasion significantly weakened diversity. ③ The DCA ordination divided the plant species into four groups： ground-growing， root-developed， tall-growing， and water-dependent. The ecological distance between each invasive plant species was relatively far， and the differentiation of functional traits contributed to their collaborative invasion. In conclusion， the plant community structure in riparian zone of Nanwan Lake in winter was relatively simple， with some species exhibiting overly fragmented distribution. These suggest that the stability of the community structure can be enhanced by optimizing water level regulation and artificially replanting native ecological restoration plants.