Padrões e tendências de 30 anos de floração em espécies arbóreas de terra firme na Amazônia Central

Abstract

Currently, much scientific effort is directed to understand the implications of global climate change on the behavior of trees over time. Understanding how the reproductive patterns of tropical tree species are related to climatic factors may be crucial for predicting future changes in tropical forests. It has been shown that flowering in tropical forests varies with species, location and climate variables. However, no previous study has quantified long-term (decadal) effects on flowering phenology in multiple tropical species between different sites. Here we quantify the relative contribution of location and climatic variables in explaining 30 years of flowering phenology in nine neotropical tree species. Flowering was recorded monthly in two sites (5 individuals per site) during the years 1982-2011. The determinants of flowering patterns were examined in two temporal scales - annual (month of first flowering and duration) and monthly (occurrence of flowering). Cross-correlations were used to understand the associations between timing of annual and monthly flowering and seven climatic variables (temperature, rainfall, humidity, Southern Oscillation Index (SOI), SOI anomaly, North Atlantic Tropical and Sea Surface Temperature). Generalized additive models were used to describe and explain patterns in flowering phenology of the nine species (Aniba canelilla (H. B. K.) Mez.; Cariniana micrantha Ducke.; Dinizia excelsa Ducke.; Dipteryx odorata (AUBL.) Willd.; Goupia glabra Aubl.; Hevea guianensis Aubl.; Jacaranda copaia (AUBL) D. Don.; Minquartia guianensis Aubl. e Parkia pendula (Willd.) Benth) in response to location and climatic variables. The phenological parameters varied significantly between species. There was seasonal variation in flowering time in all species. The monthly phenological parameter (occurrence of flowering) was correlated with climate for most species when compared to the annual parameters (month of first flowering and duration). The phenologies of only one species (Dinizia excelsa) were not significantly associated with any climate variable. When the additive effects of location and climate were considered, climate had no influence on annual or monthly flowering in members of the family Bignoniaceae (Jacaranda copaia), Fabaceae (Dinizia excelsa), Lauraceae (Aniba canelilla) and Olacaceae (Minquartia guianensis). The diferences between sites proved to have greater influence on species flowering. In general, individuals in RD showed a greater occurrence flowering, which started earlier and lasted longer than in EEST. Most species showed annual flowering with an intermediate duration. The flowering peak occurred between the months of June to October (dry season). There were changes in flowering over the 30 years examined, but climatic variations influenced only weakly the flowering of some species. Over 30 years there was a tendency of Hevea guianensis start blooming later and increase the duration of flowering, in Dipteryx odorata first flowering tended to occur sooner and the duration of Parkia pendula increased. A detailed understanding and long-term phenology of species was important to allow for a robust assessment of climate change impacts and should be done in a larger number of species.