Morfologia polínica de táxons de Poaceae do rio grande do sul: uma abordagem para distinguir vegetações campestres e florestais no sul do Brasil

Abstract

Poaceae pollen grains identified in quaternary records can only indicate the grassland vegetation and does not allow more environmental and ecology inferences due to the uniform morphology of the pollen grains. In this sence, analyses were performed in optical and scanning electron microscopy in different taxa representing all tribes and subfamilies of Poaceae family of the Rio Grande do Sul to assess whether their pollen grains can be distinguished in relation: (i) to the type of vegetation (grassland and forest), (ii) to the photosynthetic metabolism C3 and C4, (iii) to the type of habit between forest species, (iv) to different taxonomic levels (genera, tribe, subfamily). Are presented pollen information about 68 species of Poaceae family distributed in the grassland or forest vegetation of the Rio Grande do Sul. Analysis by optical and scanning electron microscopy allowed to distinguish the pollen grains in relation to the type of vegetation of species (grassland and forest). Pollen grains of forest species showed larger size than grasslands taxa, as well as species with photosynthetic metabolism C3 showed trend to have pollen grains larger than taxa with metabolism C4. Patterns in sizes of pollen grains of the forest species in relation to the habit were also obtained, highlighting the distintic size of pollen grains of the ambuseae tribe. Based on the results, the Poaceae pollen grains can be used as environmental indicators for better characterization of the dynamics and reconstructions vegetation in southern Brazil.