Reproductive phenology and seed dispersal syndromes of woody species in the Brazilian Chaco

Questions(1) Do woody species flourish and fructify according to environmental seasonality? (2) Is there a positive correlation with dry/rainy season? (3) Are the flowering and fruiting of woody species positively correlated with rainfall, temperature and photoperiod? (4) Do anemochorous, autochorous and zoochorous species fructify according to environmental seasonality, i.e. dry or rainy season? LocationThorn forest, southern Midwest Brazil. MethodsQualitative data collection included the presence or absence of flowers and/or fruits of each species, independently of the development phase of their reproductive organs. A Rayleigh test was used to determine if flowering and fructification were seasonal throughout the year and to detect possible significant seasonal patterns. Spearman's rank correlation and Bonferroni correction were used to determine possible correlations between phenological events and rainfall, temperature and photoperiod. ResultsFlowering and fruiting of the woody community showed a low degree of seasonality. No significant correlations were found between flowering and fructification and the climatic variables studied: temperature, photoperiod and rainfall. Approximately 60% of the zoochorous species bore fruit during the rainy season, but with a low degree of seasonality. The fruiting of anemochorous species presented two opposite points of higher frequency, corresponding to the transition period between rainfall and drought and the rainy season. No seasonality was found. Autochorous species showed no pattern of seasonal fruiting. ConclusionsThe data on flowering and fruiting in the community studied are unexpected and contrast with studies performed in seasonal environments. Seed dispersal syndromes showed no significant seasonal events. These results differ from those usually found in markedly seasonal environments. The Brazilian Chaco can be considered an arid environment in which abiotic syndromes prevail in a manner similar to that seen in tropical dry forests.