How different is the forest on post-coal mine heap regarded as novel ecosystem?

Abstract

Forests are the dominant terrestrial ecosystems on the Earth. During natural succession, a quite known pattern of changes occur (i.e., the process of a gradual assemblage of plant species and associated organisms best adapted to the current habitat conditions). Much less is known about novel ecosystem establishment's primary spontaneous successional mechanisms due to human agency such as post-coal mine heaps habitats. The post-coal mine heaps are sites of pure mineral substrates and constrain (e.g., temperature, acidity, drought, salinity) habitat conditions. These conditions are variable both in time and space. Regardless of all these constraints, diverse vegetation is soon spontaneously developing on these sites. A characteristic feature of the vegetation successional development on post-coal mine heaps is the emergence of non-analogous species assemblages when comparing to the natural and seminatural vegetation communities and ecosystems.This study aimed to compare the forest spontaneously developed on the mineral novel material habitat of the post-coal mining heap, with forests in the surrounding, on non-industrial habitats (located in Silesian Upland (South Poland)) in taxonomic, phylogenetic, and functional diversity at alpha (within-site) and beta (among sites) levels. The functional traits values of the recorded species composition were calculated to assess, e.g., the taxonomic alpha diversity Shannon's diversity and evenness index, Simpson index, functional richness (FRic), functional dispersion (FDis), functional divergence (FDA), and functional evenness (FEve). Rao's entropy has standardized the Biotic Novelty Index (BNI) to reflect the proportion of functional diversity contributed by novel species composition.The results revealed higher functional richness and dispersion in coniferous forests than in forests on heaps. The plots from coniferous forests and heaps were distinctly differentiated in terms of species composition. No difference occurred in functional evenness and divergence. Vegetation patches of coniferous forests had 19% higher species richness and twice higher Faith's phylogenetic diversity, while no differences in species diversity described by Shannon's diversity index have been recorded. An almost thirty times higher biological novelty index in forests on heaps than in coniferous forests patches has been recorded. The RLQ - analysis of relationships between plant traits, species composition and environmental variables revealed significant associations between EIVs and type of habitat and plant traits. The plant traits such as SLA and SM seem indifferent and do not differentiate the two studied habitats.The results showed that both understanding mechanisms by which these habitats are shaped and recognizing their biological potential and values are essential for nature conservation and management and challenge future studies.