Impact of Ligustrum lucidum invasion on the structure and functioning of coastal dry forests: a case study from Argentina

The Ligustrum lucidum invasion of Argentinian forests has significantly altered their structure and functioning. This study assesses and compares structural variables (tree density, sapling density, basal area, understory cover) and functional variables over time (leaf area index (LAI), fraction of photosynthetically active radiation (fPAR), relative growth rate (RGR) and net primary productivity (NPP)) through field measurements in preserved, partially invaded and invaded dry forests in natural reserve “El Destino”, Buenos Aires province. Results show that the high L. lucidum RGR enhanced light-use capacity of invaded forests, evidenced by an increase in tree density, a 50% higher LAI and consistently elevated fPAR compared to preserved forests. However, the expected NPP increase was not observed. Invaded forests intercepted over 95% of solar radiation year-round, suppressing understory development and produced a dense leaf litter layer. The linear relationship between LAI and canopy height highlighted vertical structure’s role in light interception. Furthermore, the high density of L. lucidum saplings in preserved forests and the presence of dead native trees in invaded forests suggest competitive displacement toward monospecific stands of L. lucidum. These findings enhance our understanding of how L. lucidum reshapes ecosystem structure and function in these native forests, providing insights for forest management.