Influence of Soil Fertility on Herbaceous Community Structure in Dunes and Swamps of the Coastal Plain of Laguna, South Brazil: An Ecological Approach

This study aims to evaluate the influence of soil nutrition on the organization of restinga communities on two different geoformations in the post-beach region. Studies were carried out at Laboratory of Morphology and Plant Ecology and Marine Biological Science Course, Joinville Regional University, in coastal plain of the municipality of Laguna, Santa Catarina, Brazil, during August 2017. A phytosociological survey was performed using 1 x 1m plots distributed along four parallel transects spaced about 200m apart (50 plots were located on parabolic dunes and 50 plots were located on swamp of intercordion depressions). Chemical characterization of the soil of the parabolic dunes and the intercordion depressions adopted conventional soil protocols. The phytosociological survey recorded 28 species distributed among 25 genera and 12 families of angiosperms. Of these species, seven were found co-occurring in parabolic dunes and swamps of intercordion depressions, whereas the others were unique to one or the other geoformation. Swamp showed bigger diversity than dunes. The most diverse families were Asteraceae (9), Cyperaceae (5) and Poaceae (5), which accounted for 79.2% of the total number of species surveyed. The dune soil had higher salinity, while the swamps had greater availability of water and fertility. The results obtained in the present study corroborate the indissociable plant-soil relationship attributed to restinga environments, specifically that increases in both species richness and abundance are associated with higher fertility and water availability of soil, and whose edaphic climax is notorious in the most settled communities near the sea.