Flowering and Fruiting Phenology of Native and Non-Native Woody Species in a Semiarid Subtropical Forest

Abstract The timing of flowering and fruiting events has major implications for community assemblies in time and space, and is an important trait for explaining plant invasion. Wolkovich and Cleland proposed four phenological hypotheses to explain invasion success; however, in semiarid subtropical forests, where non-native woody species are highly invasive, these hypothesis have been poorly tested, with multiyear studies being even less scarce. We answered the following questions: 1) Which of the strategies proposed by Wolkovich and Cleland do non-native species exhibit in their flowering and fruiting phenology? 2) Does temporal variability in flowering and fruiting differ among individuals of native and non-native species? We measured the beginning and length of flowering and fruiting phenology of the most frequent native and non-native woody species during four consecutive reproductive periods. We found differences in the phenological patterns. Non-natives showed a delay in flowering and fruiting, coinciding with the Vacant niche hypothesis, and had a longer fruiting phenology, as predicted by the Niche breadth hypothesis. Many individuals of native species showed high temporal variability in flower and fruit production, with a sharp reduction or even absence of individuals with flowers or fruits in some periods. Contrarily, individuals of non-native species showed higher temporal stability in flower and fruit production. The different phenological strategies developed by non-native species generate different interactions and windows of opportunities that may explain invasion. These new strategies may also have profound consequences on ecosystem processes and functions.