Forest dynamics and invasion of Ligustrum Lucidum in an urban alluvial Atlantic Forest fragment

Abstract

Alluvial forest environments are vulnerable, representing one of the most degraded ecosystems globally. This study evaluated the dynamics of an urban Alluvial Mixed Ombrophilous Forest and the invasion of Ligustrum lucidum W.T.Aiton (Oleaceae) in Guarapuava-PR, Brazil. Diameter at Breast Height (DBH ≥ 5 cm) and height measurements of tree individuals were carried out in 72 study plots of 100 m² each, between 2011 and 2022, and phytosociological descriptors and Relative Growth Rates and Mortality Rates were calculated. Analysis of Variance compared the abundance of the invader over the years, and Pearson correlation investigated its relationship with native species’ richness. Other comparisons used Generalized Linear Models, with Bonferroni correction at 5% significance level. L. lucidum showed similar mean diameter to the native tree community, but its mean height was significantly higher. Gymnanthes klotzschiana, Matayba elaeagnoides, and L. lucidum had higher phytosociological descriptors and sociological position values. The growth rate of L. lucidum was higher along with Casearia decandra, and the alien species had a low mortality rate compared to Zanthoxylum rhoifolium and Ocotea puberula. However, there was no significant increase in the abundance of L. lucidum, although a weak negative correlation between native species richness and invader abundance was observed. The invasion degree indicated a 5% increase in the alien population during the study period. This study provides a basis for investigations into the dynamics of alluvial forests and the biological invasion process. Keywords: araucaria mixed forest, invasive alien species, phytosociology.