Invasive Species Compendium

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Abstract Full Text

Effects of time since invasion and control actions on a coastal ecosystem invaded by non-native pine trees.

Abstract

1. Invasive non-native trees cause structural and functional changes in plant communities, which tend to increase over time since invasion. Native vegetation responses after control operations provide important information for restoration. 2. We evaluated the effects of time since invasion and of pine control on plant community structure and on functional traits in a coastal open ecosystem in southern Brazil. We compared richness, diversity, abundance and cover of woody and non-woody native plant species, as well as species composition and community-weighted means (CWM) based on functional traits (dispersal syndrome, fruit type, maximum height and shade tolerance) of plant communities, in four conditions: a non-invaded area, an area where pines were controlled (managed area), an area of recent invasion and an area invaded longer ago. 3. Woody species abundance, richness and diversity declined over time since invasion. However, while abundance recovered to the point of not differing from the non-invaded condition in areas where pines were controlled, species diversity and richness were lower in the managed area than in the area that was never invaded. The effects of pine invasion on richness and diversity of non-woody plants did not increase over time, but plant cover progressively diminished. 4. Woody and non-woody species composition varied between the four conditions. Species composition similarity was lower between conditions for non-woody than for woody species. CWM differed between the older invasion and the other conditions, determined especially by native plant height and shade tolerance. Taller plants and more shade tolerant native species were exclusively sampled in the older invasion. 5. Synthesis and application: Pine invasion reduced species abundance, plant cover, richness and diversity, altering the composition of plant community. The escalation of negative temporal effects of pine invasion was observed on the composition of woody and non-woody species and on functional traits. Although pine control favoured the natural regeneration of non-woody species, diversity of woody species in the area submitted to pine control was lower than in the non-invaded condition. Restoration activities are therefore required to increase woody species diversity. These results provide relevant guidance for the restoration of coastal ecosystems following invasive pine control.