Fenologia de uma comunidade de duna frontal no sul do Brasil

Abstract

This study aimed to evaluate the patterns of plant phenology of a coastal sand dune in the State of Santa Catarina (27°S). The phenological patterns were investigated in relation to climatic factors and compared to those described for other sand-dune communities on the Brazilian coast. The phenology of foredune plant species was evaluated at Joaquina Beach, Santa Catarina Island, State of Santa Catarina. A method based on the frequency of species was employed. The occurrence of each species and the phenophase presented was calculated at monthly intervals. Species were observed flowering or fruiting throughout the entire year similar to the communities at lower latitudes (São Paulo State: 24°S and Espírito Santo State: 20°S). The greater number of species in flower and in fruit occurred in months of high rainfall and elevated temperatures. Many species were in flower in winter, different from that which occurs in the extreme south of Brazil (Rio Grande do Sul State: 32°S). However, a reduction in the frequency of flowering was registered for some of these species in this period. This suggests a certain restriction by lower temperatures, as in southern Brazil, or by winter month water deficits. Among the 34 monitored species, 15 presented episodes of germination, mostly in autumn/winter, when temperature and rainfall decrease. Germination in autumn/winter is discussed here as an avoidance mechanism of sand dune species from the highest temperatures and evapotranspiration conditions present in summer. Vegetative sprouting was registered for 17 species, in a similar period to that events of germination. Dry periods in August and September reduced events of flowering, fruiting, germination and sprouting.