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

摘要

The Poaceae species have their use for food known in Brazil and in the world. Maize, which today accounts for 21% of human nutrition, was changed 9,000 years ago from Teosinte. Many indigenous people grow maize in South America to feed the tribe. In Brazil, several Poaceae species of African origin were introduced accidentally purposely in the colonial period, to be used as fodder, as was the case of annoni grass ( Eragrostis plana Nees). Palynological studies may reconstitute a vegetation of the past, but due to the similarity of Poaceae pollen grains, so far maize ( Zea mays L.) can be identified with the safety of the palynological studies. The aim of the study here is to identify and describe the pollen grains of Poaceae exotic cultivated species. The pollen grains were collected from herborized plants and processed by usual techniques of palynology (acetolysis). The results allow identification of three pollen groups (pollen of ornamental, cereal and corn plants). Pollen morphology of 14 species of exotic Poaceae in Rio Grande do Sul state showed differences in sizes of pollen grains. The results of this research showed that cultivars of grasses can be identified in sedimentary profiles. However, some pollen grains have the size of pollen similar to Poaceae pollen of native species. Thus, it is necessary knowledge about the vegetation of study area and surrounds distributed cultivars of grasses. Nevertheless, this pollen database is important to mapping with more precision the cultivation of these cereals in the Late Holocene.