Successional Changes in Seed Banks in Abandoned Rice Fields in Gwangneung, Central Korea

In order to understand the role of seed banks for restoration, seed banks in abandoned rice fields in the Gwangneung National Arboretum, central Korea were investigated using the seedling emergence method. The study sites represented three stages: an initial stage dominated by forbs such as Persicaria thunbergii and Juncus effuses var. decipiens, a middle stage dominated by Salix, and a late stage dominated by Quercus aliena and Prunus padus (in nearby riparian forest chosen as a reference stand). DCA ordination arranged the stands according to the number of years since abandonment. CCA ordination identified the dominant environmental variables correlated most closely with Axes 1 and 2 as $Mg^{2+}$ (intraset correlation was 0.827) and $K^+$ (intraset correlation was -0.677), respectively. Species richness and diversity decreased from the initial stage (H'=2.61) to the middle (H'=1.79) and late (H'=0.75) stages. A total of 49 species $(/m^2)$ and 18,620 seedlings $(/m^2)$ emerged out of the seed bank samples. The DCA ordination and similarity analysis detected a large discrepancy between the composition of the actual vegetation and the seed bank. We conclude that the contribution of seed bank to restoration is low. However, seed bank may help the recovery of forbs after disturbance. Some of our results are consistent with the tolerance model of succession whereas others follow the trajectory of the facilitation model. More research on succession will be required to understand the underlying mechanisms.