Phenology of the tree community in a seasonal forest in southern Brazil

Seasonal variations in environmental factors, such as precipitation, influence plant phenology and the relative importance of each factor, differ according to the ecosystem in question. In this study, we evaluated the phenology of 60 tree species in a seasonal semi-deciduous forest located at the southern border of the tropical zone (23 degrees 26 ' 35"S and 51 degrees 15 ' 30"W) during 3 years. We aimed to investigate the relationship of leaf fall, leaf flushing, budding, flowering, immature and mature fruit phenophases with precipitation, temperature and photoperiod. We also analyzed whether the phenological patterns of tree community were seasonal and similar between consecutive years. Although the climate of the region is classified as Cfa, there are two distinct season: a hot humid summer and a cold drier winter. Leaf fall occurred predominantly in the dry season, with leaf flushing and flowering at the end of the dry and early wet season. The mature fruits were observed throughout the year. For the six phenophases analyzed, the percentage of species did not differ among the three study years. The tree community presented, in general, weakly seasonal phenological patterns, mainly in response to variations in temperature and photoperiod. The mature fruits showed seasonal patterns when the species were grouped by dispersal syndrome. This predictability suggests that small inter-annual variations in precipitation and temperature are not relevant for the studied tree species' phenology.