Phenology of three species of Adiantum L. (Pteridaceae) in a Semideciduous Forest of Pernambuco State, Brazil

Abstract

Water deficit in seasonally dry environments, such as semi deciduous forests, appears to be the main determinant of the selection of species with mechanisms that allow adaptive responses to this type of stress. Thus the availability of water influences the establishment of plants in an area and their growth and dormancy periods. The present study aimed to identify dry- and rainy-season survival strategies developed by three species of ferns occurring in a semi deciduous forest located at Aliança (Pernambuco, Brazil). Field observations were carried out to monitor the development of populations of the three species. Thirty-two individuals of Adiantum petiolatum Desv., 30 of A. deflectens Mart. and 13 of A. pulverulentum L. were studied. The phenological data were correlated to climatological data of the study period. The populations showed low and irregular frond production, occurring in both dry and rainy seasons, exhibiting positive correlation with relative humidity and rainfall to A. deflectens and A. petiolatum. Constancy in production of senescent fronds in the three populations was observed, being inversely correlated to rainfall and the relative humidity only in Adiantum deflectens. The presence of fertile fronds was continuous in the three populations, however, this phenophase in Adiantum petiolatum was positively correlated to temperature and relative humidity. Results indicate the existence of a distinct influence of the climate on the three species studied.

Key words: autoecology, fertility, leaf production, climatic variables, ferns, leaf senescence.