Abstract: The Jingxin Wetland, located in the lower reaches of the Tumen River, plays a vital role in maintaining regional ecological balance as the only offshore wetland in Jilin Province. In recent years, many paddy fields in the Jingxin Wetland area have been abandoned, and the area has increased year by year. As a semi-natural wetland formed by natural succession, abandoned paddy fields have a significant impact on regional biodiversity, but the mechanism behind the transition of plant communities through natural succession remains unclear. In this study, we focused on the Jingxin Wetland, and identified its site and biological habitat characteristics by performing a site survey and literature survey. To determine the changes of plant diversity in the process of natural succession, we compared the plant species and communities of natural wetland with semi-natural wetland of different abandoned times by using space series analysis instead of time series analysis. A total of 99 plant species belonging to 64 genera of 33 families were identified in natural wetland and abandoned paddy fields. The species primarily consist wetland hydrophyte herbaceous, and aquatic plants. Based on the community characteristics, Cyperaceae, Polygonaceae, and Poaceae were the dominant species in the Jingxin Wetland. As the time of abandonment increased, the dominant species of the semi-natural wetland plant community shifted towards the dominant species of the natural wetland plant community. The plant diversity of the abandoned paddy fields was much higher than that of the natural wetland; however, the diversity decreased as succession time progressed and began to resemble the natural wetland community. Nevertheless, compared with wetlands at the same latitude, the succession rate of the abandoned paddy fields was slower, thereby highlighting the influence of soil, water, and organic matter in the subsequent restoration of abandoned paddy fields and the need to continuously strengthen wetland management and protection.

Key words: Jingxin Wetland, abandoned paddy field, wetland plant, community succession, plant diversity, the lower reaches of Tumen River