Phenology of Araucaria Forest fern communities: comparison of the influence of natural edge, artificial edge, and forest interior

The edge effect, triggered by habitat fragmentation, alters forest microclimates and influences the life cycle of plants. Phenology may indicate the first changes in phenological patterns in response to the effects of climate change. Climate regulates the phenology of ferns and climatic triggers influence plants in tropical and subtropical regions differently. This study analyzed and compared the phenology of fern communities of three sub-areas — natural edge, artificial edge, and forest interior — of a fragment of Araucaria Forest in the Floresta Nacional de São Francisco de Paula, Rio Grande do Sul, Brazil, and its relationship with meteorological, astronomical, and edaphic variables. Abiotic and edaphic data were monitored concomitantly with phenological data (leaf renewal and senescence and sporangia formation) in each sub-area over a biennium. Temperature, air humidity, and soil moisture, which undergo changes with the edge effect, influenced edge plants. Leaf renewal was the main phenophase showing strong indication of changes in vegetative patterns in natural and artificial edge communities. Among the communities, that of the artificial edge signaled phenological changes that could compromise the development of ferns if effects intensify over time. In this respect, the phenology of artificial edge ferns differed from that of plants growing in originally natural formations (natural edge and forest interior), showing that exogenous transformations represent a new environmental situation for ferns to develop.