Cushion plant Silene acaulis is a pioneer species at abandoned coal piles in the High Arctic, Svalbard

Abstract

Background Abandoned coal piles after the closure of mines have a potential negative influence on the environment, such as soil acidification and heavy metal contamination. Therefore, revegetation by efficient species is required. For this, we wanted to identify the role of Silene acaulis in the succession of coal piles as a pioneer and a nurse plant. S. acaulis is a well-studied cushion plant living in the Arctic and alpine environments in the northern hemisphere. It has a highly compact cushion-like form and hosts more plant species under its canopy by ameliorating stressful microhabitats. In this research, we surveyed vegetation cover on open plots and co-occurring species within S. acaulis cushions in coal piles with different slope aspects and a control site where no coal was found. The plant cover and the similarity of communities among sites were compared. Also, the interaction effects of S. acaulis were assessed by rarefaction curves. Results S. acaulis was a dominant species with the highest cover (6.7%) on the coal piles and occurred with other well-known pioneer species. Plant communities on the coal piles were significantly different from the control site. We found that the pioneer species S. acaulis showed facilitation, neutral, and competition effect in the north-east facing slope, the south-east facing slope, and the flat ground, respectively. This result was consistent with the stress gradient hypothesis because the facilitation only occurred on the north-east facing slope, which was the most stressed condition, although all the interactions observed were not statistically significant. Conclusions S. acaulis was a dominant pioneer plant in the succession of coal piles. The interaction effect of S. acaulis on other species depended on the slope and its direction on the coal piles. Overall, it plays an important role in the succession of coal piles in the High Arctic, Svalbard.

Plant co-occurrence patterns and soil environments associated with three dominant plants in the Arctic

“…According to Castro et al (2002), the nursing effect on the lower soil-temperature and higher soil-moisture provided by plant cover (patch area) was clearly presented inside and at the edge of Salvia lavandulifolia as a nurse plant. In addition, the height of Silene in this study was rather low compared to the 2-8 cm height described by Oh and Lee (2021).…”

“…Grau et al (2014) showed that patches of Dryas octopetala × intermedia have a distinct negative effect on small-scale plant richness. Silene acaulis in Ny-Ålesund showed all interactions (positive, negative, and neutral effects on species richness) according to the different aspects (Oh and Lee 2021). Therefore, to fully understand species co-occurrence, focusing on either facilitation or competition independently may be inadequate (Losapio et al 2021).…”