Soil-vegetation relationships and community structure in a "terra-firme"-white-sand vegetation gradient in Viruá National Park, northern Amazon, Brazil

Bruno A.F De Mendonça,Júlia G.F De Mendonça,Bruno N.F Vasconcelos,Elpídio I Fernandes Filho,Carlos E.G.R Schaefer

doi:10.1590/0001-3765201720160666

Abstract

Viruá National Park encompasses a vast and complex system of hydromorphic sandy soils covered largely by the white sand vegetation ("Campinarana") ecosystem. The purpose of this study was to investigate a vegetation gradient of "terra-firme"-white sand vegetation at the Viruá National Park. Nine plots representing three physiognomic units were installed for floristic and phytosociological surveys as well as to collect composite soil samples. The data were subjected to assessments of floristic diversity and similarity, phytosociological parameters and to statistical analyses, focused on principal components (PC) and canonical correspondence analysis (CCA). The vegetation of the Campinaranas types and Forest differed in biomass and species density. Ten species, endemic to Brazil, were particularly well-represented. PC and CCA indicated a clear distinction between the studied plots, based on measured soil variables, especially base sum and clay, which were the most differentiating properties between Campinarana and Forest; For the separation of the Campinarana types, the main distinguishing variable was organic matter content and cation exchange capacity. Higher similarity of Campinaranas was associated to a monodominant species and the lower similarity of Forest was related to the high occurrence of locally rare species.

Highlights

Viruá National Park (VVNP), located in southcentral Roraima, in the lower Rio Branco region, covers an area of 227,011 ha, of which about 60% belong to the Campinarana ecosystem (Mendonça et al 2013)
The chemical and physical data for the three soil vegetation types are presented in Table II with the mean and standard deviation for each soil variable
According to Legendre (1993) four fractions can be identified in Figure 3: nonspatial environmental variation, with 0.085; spatially structured environmental variation, with 0.556; spatial variation of the target variables that is not shared by the edaphic variables, with 0.186; and, unexplained, nonspatial variation, with 0.174. These results indicate that our variables, edaphic and spatial components, explain 83% (X1 + X2) of variation in community composition

Summary

Introduction

Viruá National Park (VVNP), located in southcentral Roraima, in the lower Rio Branco region, covers an area of 227,011 ha, of which about 60% belong to the Campinarana ecosystem (Mendonça et al 2013). Located on large patches of sandy soil, Campinaranas are found from the upper Rio Negro beyond the north-northwest of Brazil to the region of Vaupés and Caquetá in Colombia to southern Venezuela, in large areas of the upper Tapajós river, along the right hand banks of the Rio Madeira, and in small patches, e.g., vegetation enclaves, in southwestern Amazonia (IBGE 1992, Duivenvoorden 1996, Oliveira and Daly 2001, Alonso 2002, Silveira 2003, Poleto and Aleixo 2005, Daly et al 2016, Adeney et al 2016). In the Peruvian Amazon, a similar vegetation on sandy soils is called “varillales”, which is known in the forests of Guyana as “wallaba” (Anderson 1981, Oliveira and Daly 2001, Alonso 2002, Adeney et al 2016). On the plains of the Brazilian coastline, the “restinga” forests and “mussunungas” have features that are very similar to those of the Campinaranas, with some species and many genera of plants in common (Anderson 1981, Oliveira and Daly 2001, Boeger and Wisniewski 2002, Prance 1996, Meira Neto 2005, Sarcinelli 2010, SaporettiJunior et al 2012)

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