Abstract

GANTES, Patricia  and  SANCHEZ CARO, Aníbal. Riparian Clear-Cutting: Changes in Diversity of Herbaceous Layer in a Pampean River (Buenos Aires, Argentina). Acta biol.Colomb. [online]. 2023, vol.28, n.3, pp.438-448.  Epub Sep 05, 2023. ISSN 0120-548X.  https://doi.org/10.15446/abc.v28n3.98405.

Clear-cutting and weeding of riparian habitats in peri-urban watercourses are common practices that may lead to a lower cover and to changes in vegetation assemblages, encompassing increments in the proportion of exotic and ruderal species. The aim of this work was to study the herbaceous assemblages prior to and along three years after deforestation in the Lujan's River riverbank, which was dominated by the invasive species Gleditsia triacanthos and other woody exotics. Four sites were sampled, on one occasion before and five times after the disturbance, assessing at each site the percentage of bare soil and the cover by species. After deforestation, the proportion of bare soil became significantly lower from 15 months on. Before the disturbance the species richness was 21, and two years later it stabilized in more than 50 species, while beta diversity remained mostly unchanged. The assemblages found before and on the first sampling after the disturbance were the most different between all pairs (ANOSIM, SIMPER). Both exotic as ruderal species increased in the first stages, and then returned to pre disturbance values. Three years after deforestation, the changes in diversity suggest that a different assemblage has established in place of the pre disturbance one. The resulting assemblage has higher cover and number of species and is co dominated by both riparian native species and disturbed environments species, while the proportion of exotic and ruderal species remains unchanged.

Keywords : Invasive species; perturbation; succession; weeding; species composition.

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