Seasonality of Flowering and Leaf-Fall in a Brazilian Subtropical Lower Montane Moist Forest

Abstract

In a lower montane moist forest of southeastern Brazil, leaf-fall was maximal (1.8-2.9 g/m2/day) during the period of greatest precipitation and high temperatures. Through most of the dry season leaf-fall was low (0.4-0.9 g/m2/day) although an increase occurred in the late dry season (1.1-1.4 g/m2/day). Number of species in flower per 10-day period was maximal (30-50) at the end of the dry season and the beginning of the wet season. Flowering was minimal during the middle and late wet season (8-22) and was moderate during the early and middle dry season (14-30). The seasonality of flowering is similar to the community-wide pattern typical of tropical forests, but the occurrence of the leaf-fall maximum during the wet season is unusual. It is suggested that, where benign climates permit, overlap of leaf generations not only provides continuous photosynthetic income but may allow energetic savings in the transfer of material from old to new leaves by obviating storage costs. To AID IN THE UNDERSTANDING of seasonality patterns in tropical plant communities that is emerging (Janzen 1967, Croat 1969, Foster 1973, Burger 1974, Frankie et al. 1974), this report provides data on flowering and leaf-fall from Reserva Biologica Nova Lombardia, Municipio de Santa Tereza, Espirito Santo, Brazil (fig. 1). Reserva Nova Loimbardia lies at latitude 19? 53' S and ranges in elevation from 700-1000 m. The altitude within the actual study area varies between 810-890 m. The following climatic data for Reserva Nova Lombardia were extracted from Ruschi (1950): mean annual biotemperature 170 C; mean annual total precipitation -1566 mm; mean annual evaporation -455 mm. From the temperature and precipitation data the vegetation is classified in the Holdridge Life Zone System (Holdridge 1967) as Subtropical Lower Montane Moist Forest. The mean annual biotemperature is exactly at the division between the Lower Montane and Premontane altitudinal belts, but because light frosts occasionally occur at the study area, and during the winter the temperature sometimes approximates 3-5? C for up to 48 hours, Lower Montane is the more appropriate characterization. Observations indicate that the vegetation is near the Moist-Wet transition rather than being typical Moist Forest. Temperatures are markedly lower during the dry season; thus moisture stress on the plants is less than in a more equatorial location with equivalent rainfall. Second, considerable cloudiness and fog are generated over Reserva Nova Lombardia as the southeast trade winds coming off the Atlantic Ocean strike the mountains a few score kilometers inland. Epiphytes, especially brormeliads, are abundant, much more so than in lowland Moist Forest of my acquaintance in Central America.