Estudio de la zarzamora (Rubus ulmifolius Schott) como leñosa invasora de bosques nativos en Uruguay

Invasive alien species (IAS) constitute a serious global environmental problem. Rubus ulmifolius (blackberry), has been reported as an IAS in our country, given that it quickly colonizes forest ecosystems, displacing native species, and generating various impacts. Despite its invasive potential, there is no history of studying blackberry in Uruguay. The general objective of this study was to study the invasion by blackberry in a riverine forest within the protected area “Wetlands of Santa Lucía”. The specific objectives were (i) to describe the degree of invasion of the forest by blackberry, evaluating its abundance and coverage under three levels of disturbance: native zone, altered zone and logged zone; (ii) study the community of shrubs and tree regenerants to evaluate the impact of blackberry on these communities, and (iii) study the relationship between the invasion of blackberry (density and coverage) and the incidence of light. The study area was a riparian forest of the San José River, in which an 80 m wide strip was cut down in 2022 for the installation of a UTE High Voltage line. In autumn 2023, 10 plots (4 m²) were randomly sampled in each area, in which data on: abundance of regenerants , species in the canopy and soil cover were collected. Then the diversity index was calculated by zone and compared between zones: density of total regenerants , density and cover of blackberry and soil cover categories. Finally, the relationship between the density and coverage of blackberry and the PAR (photosynthetically active radiation) transmitted was evaluated. The species under study presented variations in its abundance and coverage associated with the disturbance gradient. Significant differences were found in the abundance of blackberry between the three areas evaluated. Likewise, it was observed that blackberry is the dominant exotic species. The sampling area that presented the greatest diversity of total and native species was the native area followed by the altered and logged area. A positive and significant relationship was found between blackberry abundance and light incidence, which reinforces the idea that changes in canopy structure are strongly involved with the degree of blackberry invasion. In the native area there is less incidence of light in the understory, given that the canopy structure is more closed, which strongly limits the abundance of blackberry. In the three areas studied, the most abundant species within the woody regenerating community was an IAS, this is highly worrying, taking into account that it is a riparian forest within a protected area of the SNAP (National System of Protected Areas). The present study shows the effect of anthropogenic degradation, in this case due to deforestation and IAS, on the diversity and structure of native forests and highlights the importance of adequate management of ecosystems within protected areas.