Abstract
This aim of this study was to distinguish grasslands from forests in southern Brazil by analyzing Poaceae pollen grains. Through light microscopy analysis, we measured the size of the pollen grain, pore, and annulus from 68 species of Rio Grande do Sul. Measurements were recorded of 10 forest species and 58 grassland species, representing all tribes of the Poaceae in Rio Grande do Sul. We measured the polar, equatorial, pore, and annulus diameter. Results of statistical tests showed that arboreous forest species have larger pollen grain sizes than grassland and herbaceous forest species, and in particular there are strongly significant differences between arboreous and grassland species. Discriminant analysis identified three distinct groups representing each vegetation type. Through the pollen measurements we established three pollen types: larger grains (>46 μm), from the Bambuseae pollen type, medium-sized grains (46–22 μm), from herbaceous pollen type, and small grains (<22 μm), from grassland pollen type. The results of our compiled Poaceae pollen dataset may be applied to the fossil pollen of Quaternary sediments.
Highlights
Pollen grains of the family Poaceae are widely found in Quaternary sediments of southern Brazil (e.g., Behling et al, 2004; Macedo et al, 2007; Bauermann et al, 2008)
Grain size distributions showed a Gaussian distribution for samples of arboreous forest, grassland, and herbaceous forest species (Figures 9B–E)
Using a data set of 68 species, we found that types of vegetation can be distinguished according to Poaceae pollen grains
Summary
Pollen grains of the family Poaceae are widely found in Quaternary sediments of southern Brazil (e.g., Behling et al, 2004; Macedo et al, 2007; Bauermann et al, 2008). Being mainly associated with grassland vegetation (Figure 1), Poaceae pollen is usually interpreted as indicative of open formations. In Rio Grande do Sul (RS), where more than 80% of Poaceae species occupy grasslands, a significant percentage (20%) of representatives of this family inhabit forest vegetation (Boldrini and Longhi-Wagner, 2011). The few descriptions or illustrations of pollen representatives presented in the study by Tedesco et al (1999), which analyzed the diameter of the pollen grains of Hemarthria altissima under different ploidy levels, noted that the average diameters were variable, depending on the ploidy. The analyzed pollen grains were not acetolyzed. Medeanic et al (2008) illustrated images of pollen grains from nine species, while Wilberger et al (2004) presented images of pollen grains corresponding to three separate species. Nakamura et al (2010), addressing the development of anther and pollen grains in Axonopus aureus, Chloris elata,h
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