Relationship between soil seed banks and adult tree distance in an abandoned area of the Mae Klong Watershed Research Station, western Thailand

Abstract The soil seed bank (SSB) is a crucial component of ecosystem resilience, particularly with regard to facilitating natural regeneration following a disturbance. In this study, species composition of the vegetation and SSB change after forest recovery, distribution pattern of SSB species, and the distance from adult trees affect SSB density were investigated in a secondary forest in the Mae Klong Watershed Research Station, western Thailand, ∼30 years after its abandonment. Soil samples were collected from a 16-ha permanent plot, and the seedling emergence method was employed to assess the species composition of emerged seedlings. All 842 emerged seedlings were identified, with 38 species representing 19 genera and 20 families. The mean seed density was 218.8 ± 9.7 seeds m−2. Key pioneer species, such as Trema orientalis, Ficus hispida, and Chromolaena odorata were identified as dominant based on their seedling density. An analysis of the distribution patterns of the SSB based on the Morisita index revealed both clumped and random patterns. A linear regression analysis was applied to categorize the species into two groups based on their seed dispersal potential: species dispersed near adult trees (e.g. Ficus spp., Croton persimilis) and those dispersed at greater distances from adult trees (e.g. T. orientalis). Our study demonstrates the importance of pioneer species in contributing to the repopulation of disrupted ecosystems and in ecological succession through their SSBs. These findings highlight the critical function of SSBs in vegetation restoration and recovery in degraded areas, providing profound implications for forest management and conservation strategies.