Fitossociologia de plantas espontâneas em agroecossistemas familiares de base ecológica Manaus – AM

Abstract

Spontaneous plants make up the landscape of conventional and organic agroecosystems. It is known that these plants fulfill ecological functions that can contribute to the sustainability of agroecosystems. However, studies on the dynamics of occurrence and occupation of spontaneous flora are necessary to establish the best management strategies. The objective of the research was to carry out a survey and floristic and phytosociological analysis of spontaneous plants in ecologically-based family agroecosystems in Manaus - AM. The study was carried out in the organic vegetable production sector of Escola Agrícola Rainha dos Apóstolos (EARA) located in the city of Manaus-AM, Km 23 on BR 174. For sampling of spontaneous plants, an inventory square launched 24 times in the area was used. The "mandala" organic garden studied is a polyculture of vegetables and fruit. Fifteen species of spontaneous plants were found in the area, belonging to 10 families, being eleven dicotyledons (73%) and four (27%) monocotyledons. The families Euphorbiaceae, Amaranthaceae, Poaceae and Portulacaceae had the highest number of individuals. The species Cyperus iria, Commelina diffuse, Amaranthus hybridus, Alternanthera tenella and Eleusine indica were the most frequent species. Cyperus would occur in 50% of the evaluated plots. Cyperus iria and Commelina diffusa had higher relative density, with emphasis on Cyperus iria. Possibly, the adaptability of this species to acid and low fertility soils and its high regrowth capacity favored its occurrence and predominance in the studied area. With regard to the phytosociological parameter IVI, Cyperus iria obtained an IVI of 86%, followed by Amaranthus hybridus (33%), Commelina diffuse (33%), Chamaesyce hirta (22%) and Alternanthera tenella (19%). Other species such as Brachiaria plantaginea, Phyllanthus niruri, Portulaca Oleracea and Priva bahiensis had low IVI. The low IVI of these species may be related to the management of the area with crop rotation and soil mulch. In the studied agroecosystem, dicots were predominant. However, in number of individuals per species, monocotyledons were higher. Cyperus iria (monocotyledonous) occurred in 50% of the evaluated plots, showing high adaptive plasticity and regrowth Brazilian Journal of Development ISSN: 2525-8761 105178 Brazilian Journal of Development, Curitiba, v.7, n.11, p. 105176-105185 nov. 2021 capacity. Therefore, further studies are needed on the management of this species in agroecologically based family agroecosystems.