Influence of the fire regime on the species richness and floristic composition of an isolated amazonian savanna - peld oeste do Pará

Abstract

Little is known about the long-term effects of fire on the floristic composition of isolated Amazonian savannas. Data from the burn regime were collected between 1997 and 2017 and related to the floristic composition in plots of 3.75 hectares spread over 10.000 hectares of savanna in the Alter do Chão-PA region, as part of the research developed by PELD Oeste do Pará. Analyzes were performed for the total species and for each plant habitat in particular (trees, shrubs, grasses + forbs, dicotyledonous herbs and lianas). We recorded 115 plant species in 43 families and 90 genera, being 24 tree species, 43 shrub species, 37 herbaceous species (including grasses and forbs) and 11 liana species. Thirty-one species were present in more than 90 % of the plots, with the highest relative frequency of Trachypogon spicatus (L.f.) Kuntze, Chamaecrista ramosa (Vogel) H. Irwin & Barneby, Rhynchospora hirsuta (Vahl) Vahl and Paspalum carinatum Humb. & Bonpl. ex Flüggé. Fire promoted changes in the vegetation of the studied savanna, reducing species richness and modifying its composition independently for each plant habitat (except grasses). However, the detection of these changes was only possible through a long series of fire data and vegetation measurements carried out in the field. Therefore, the maintenance of Long Term Ecological Projects is essential to predict and manage current patterns, which results in improved landscape management and biodiversity conservation of the isolated Amazonian savannas.