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

The identification of environmental changes by human action in the past is crucial for recovery plans and preservation of natural areas. Changes of the landscape (by human action) and natural shifts of vegetation can be showed by pollen records analysis. In this sense, pollen description of modern plants is important for use as a database for the identification of pollen samples of past. The indigenous human occupation is indicated, principally, by high concentrations of carbonized particles (linked to fire management) and a decrease of the percentage of pollen of forest species in the Quaternary sediments. While the occupation by post-Columbian settlers is indicated by pollen grains of crops or species to the plantation, such as Pinus sp. and Eucalyptus sp.1 In southern Brazil, these pollen indicators are recorded at least 2.000 BP.2–6 However, the corn is the only crop species of grasses recorded (Figure 1) in the Quaternary samples of the region.4–7 Many species of crops belong to Poaceae family. However, the distinction of pollen grains of native and crop species is difficult due to uniform pollen morphology of Poaceae species, except the pollen of corn that has size very large.8,9 The pollen morphology of many crop and native species are analyzed in the Europe continent.10 Based on the measurements of the pollen grains, the authors were able to distinguish between cereal and native pollen grains.10 On the other hand, other cultivated species such as ryegrass (Lolium multiflorum) have pollen grains that cannot be distinguished from native Brazilian taxa.11,12