The phenology of Ligustrum lucidum (Oleaceae): climatic niche conservatism as an important driver of species invasion in Araucaria forest

Abstract

Phenology expresses strategies related to resource use and can play an important role in the success of invasive plants. Araucaria forests are highly fragmented ecosystems that are increasingly impacted by invasive plants, such as Ligustrum lucidum (Oleaceae). The present study aimed to describe the phenological events of L. lucidum; identify the influence climate has on its phenophases; and compare reproductive phenophases between L. lucidum and that of Araucaria forest. The phenological study was conducted over the course of 24 months, with the intensity of each phenophase being evaluated by the Fournier Index. Ligustrum lucidum exhibited phenophases throughout the entire year in Araucaria forest, all of which exhibited a seasonal pattern except for leaf fall. The same pattern was observed for the species in its native area. Day length was the best predictor of the phenology of L. lucidum. The reproductive phenology of L. lucidum differed from that of Araucaria forest, especially with regard to fruiting. The influence of day length on the phenophases of L. lucidum seems to be part of a strategy for efficient resource acquisition and allocation. The competitive advantage of L. lucidum in Araucaria forest may be due to the maintenance of its climatic niche, which gives it a different reproductive phenology in comparison to native species. The present study shows how phenology can play an important role in the invasion process and highlights the importance of creating management strategies to avoid the spread of L. lucidum in the already threatened Araucaria forest ecosystem.