The successive trend of vegetation confirms the removal of non-indigenous woody species as an insufficient restoration action

Abstract

Invasive woody species can substantially affect their environment and communities, enhancing the interest in conservation management. Non-indigenous dwarf pine (Pinus mugo) in the treeline ecotone of the Eastern High Sudetes Mountains and its experimental removal is the model example. We asked how species composition and diversity develop after it is clearcut, and what are the main drivers leading to alpine grasslands restoration. On the study site (Jeseniky Mts., the Czech Republic), three distinct habitats were distinguished: plots after clearcut, alpine grasslands, and dwarf pine plantation. Plant species composition was assessed by means of phytosociological releves together with selected plant traits and environmental factors. We compared temporal trends in species number, diversity, and plant traits among the habitats. Species richness and diversity has increased since the dwarf pine was clearcut. This trend was the same for all three types of habitats studied, although they were significantly different in spatial compositional heterogeneity and species structure. Species composition among study habitats differed and went through its own successive trend of community development during time as the consequence of species turnover. We revealed that light-demanding plant species preferring low nitrogen concentrations were associated with the successional trend after the dwarf pine was clearcut. Dwarf pine removal creates conditions for alpine grassland restoration, but restoration can take a long time because of the environmental conditions, dwarf pine legacy, and plant traits that determine the succession direction. We recommend implementing adaptive management with long-term monitoring followed by actions to correct the desired state.