Biotic and abiotic changes in subtropical seasonal deciduous forest associated with invasion by Hovenia dulcis Thunb. (Rhamnaceae)

Abstract

Several tree species are found among the most well-know and impacting invasive plants that produce changes in richness, abundance and composition of native plant species as well as in environmental characteristics and ecosystem functioning. Hovenia dulcis Thunb. (Rhamnaceae) is a tree native to East Asia, invasive in southern South America in different forest ecosystems. This study was aimed at assessing the effects of H. dulcis on richness, abundance and composition of regenerating species in seasonal deciduous forest (SDF) by comparing invaded and non-invaded areas. The existence of correlations between abundance and richness of regenerating species with age and density of the invasive species, as well as with characteristics of canopy openness, litter thickness, slope, and soil moisture, was investigated in areas invaded by H. dulcis. Differences observed in canopy openness and litter tickness between areas invaded by H. dulcis and control areas suggest that H. dulcis is able to change environmental conditions on a local scale. Although no difference was observed in species richness between areas with and without H. dulcis, the differences registered in abundance and composition of regenerating species make the impact by H. dulcis on regeneration patterns in SDF fragments evident. The impacts caused by H. dulcis on SDF confirmed by this study highlight the need for its control in legally protected areas and their immediate surroundings, as well as for the adoption of public policies to promote the substitution of H. dulcis for locally native species.