Study on Plant Community Succession of Large River Bars Caused by Massive Floods

Jae-Hoon Park1*, Se-Hee Kim2, Kyeong-Mi Cho1, Young-Han You1

(1Department of Biological Science, Kongju National University,

2Ecological Restoration Team, National Institute of Ecology)

Abstract: Vegetation succession is a fundamental principle of ecological restoration. This study investigates the plant community succession of vegetation on large river bars in relation to flood scale and identifies the driving factors of succession within a 1-km upstream section of the Sejong Weir on the Geum River, one of the large rivers in the Republic of Korea. The study found that changes in bed material on river sandbars caused by massive floods led to significant changes in vegetation coverage. After floods, when the particle sizes of bed material exceeded those of sandy loam, vegetation coverage increased. In contrast, smaller particle sizes tended to eliminate the early established vegetation. In eroded areas of the sandbar, communities of Salix chaenomeloides with well-developed deep roots were dominant, while in depositional areas, Phragmites japonica communities, which expand primarily through runners, dominated the bare land exposed by the massive flood. In sandbars affected only by small floods, P. japonica and S. chaenomeloides emerged as pioneer species in low floodplain areas where soil organic matter was poorly accumulated. These findings suggest that in eroded areas of sandbars in monsoonal regions with large rivers, where the impact of floods is significant, introducing flood-resistant S. chaenomeloides and planting P. japonica early in depositional areas can help maintain stable restored vegetation. Additionally, the primary factor determining vegetation succession in this area is the bed material altered by floods. Thus, preserving and managing bed material is crucial for the successful restoration of vegetation on large river bars.

Acknowledgement: This work was supported by Korea Environmental Industry & Technology Institute (KEITI) through Wetland Ecosystem Value Evaluation and Carbon Absorption Value Promotion Technology Development Project, funded by Korea Ministry of Environment (MOE) (2022003630003).