Poaceae Pollen from Southern Brazil: Distinguishing Grasslands (Campos) from Forests by Analyzing a Diverse Range of Poaceae Species

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.

Anthropic pollen indicators: poaceae pollen of non-native species in Southern Brazil

“…In the last decade, deepening pollen analyzes in native Poaceae species have provided ecological inferences for application to pollen records. [19][20][21][22][23] These modern Poaceae pollen database allowed analysis of Poaceae pollen grains of Quaternary sediments that showed dynamics of grasslands vegetation in the past. 24 Even so, gaps still have to be filled on the pollen morphology of species of this family introduced in South America to more accurately identify the human occupation in the region during the Holocene.…”

“…Pollen data of non-native grasses will be compared with the data of native Poaceae pollen contained in the works of Radaeski (2015). [21][22][23][24][25]…”

Cedrus atlantica pollen morphology and investigation of grain size variability using laser diffraction granulometry

“…Grain size may be studied to improve the taxonomic resolution of pollen identification, for example with Pinus pollen (Desprat et al 2015), Poaceae pollen (Radaeski et al 2016), and indeed with Cedrus pollen (Fujiki et al 2003). Pollen size has also been correlated with genome size and may indicate polyploidy (three or more chromosome sets) in plants (Gould 1957;Kapadia & Gould 1964;Bennett 1972;Tate et al 2005;Knight et al 2010;De Storme et al 2013).…”

Access of Dynamics Vegetation during Holocene by Poaceae Pollen Grains

“…Though the pollen grains of the family Poaceae are widely found in Quaternary sediments, the Poaceae pollen has been low taxonomic resolution due to similar pollen morphology between species (monoporate and spheroidal pollen grains). However, studies on modern and fossil pollen grains of many species analyzed in the last years reveal more ecological inferences from Poaceae pollen, principally species of grassland of the South America, included Rio Grande do Sul state of Brazil [3][4][5][6]. These works provide ecological information that may be important to the reconstruction of past vegetation, such as about forests, grasslands, herbaceous and arboreal species, C3 and C4 species (species with C4 metabolism …”

“…Analysis about sizes of pollen grains of plants shows that forests species have a size larger than pollen of grassland species [3]. Furthermore, some species showed diporate aperture that allows identifying palynomorphs of Poaceae in the high resolution [6] ( Figure 1).…”