Poaceae communities in the savannas of the Amazon Estuary in Brazil

Abstract

We sought to identify the major environmental factors that affect the diversity and distribution of Poaceae in the savannas of the Amazon Estuary. The study was conducted across seven areas of savanna in the Amazon Estuary, within which 160 subplots of 1 m 2 each were established within four 10 × 100 m plots. Soil samples were collected at a depth of 0-20 cm. A total of 24 Poaceae species were recorded. Only two were common to all of the areas studied (Axonopus aureus P. Beauv. and Anthaenantia lanata (Kunth) Benth). The edaphic factors that most influenced the Poaceae in the savannas studied were organic matter, coarse sand, and silt contents. Conversely, rainfall had no effect. The floristic and structural characteristics of the savannas studied suggest that Poaceae communities exhibit low diversity and a peculiar distribution pattern in which a group of species predominate in a given stretch, creating a homogeneous physiognomy. Our findings suggest that the structure of these communities is related to a gradient of soil texture, the percentage of Axonopus and Trachypogon coverage increasing and decreasing, respectively, along that gradient. These data can contribute to the understanding of plant-soil interactions in this environment, promoting strategies for conservation, management, and revegetation.

Evolving in isolation: Genetic tests reject recent connections of Amazonian savannas with the central Cerrado

“…Moreover, these populations arguably should be considered as unique Cerrado environments in conservation efforts of the biome, given their relatively long isolated history from the CC (see Table 2). Even though most AS display much less species diversity than the CC (but see Ratter et al, 2003 for exceptions), some AS contain more than 250 plant taxa (Miranda, Absy, & Rebelo, 2003;Sanaiotti, 1997), in addition to vulnerable and endemic species of birds, reptiles, amphibians, and plants (Barbosa, Campos, Pinto, & Fearnside, 2007;Carvalho, 1997;França, Mesquita, & Colli, 2006;Rocha & Miranda, 2014). It is also important to note that the number of species in the AS most likely is larger considering that these areas are highly understudied (Carvalho & Mustin, 2017).…”

Poaceae das restingas da Ilha do Maranhão, Estado do Maranhão, Brasil

“…Os gêneros de maior representatividade foram Paspalum L., com quatro espécies (P. (Maciel et al 2009, Rodrigues & Filgueiras 2014. Rocha et al (2014) também encontraram Paspalum como gênero de maior riqueza para uma faixa do litoral amazônico.…”

“…São escassos também os estudos envolvendo a família que abrangem a faixa do litoral amazônico, que compreende cerca de 1,5 mil km, englobando os Estados do Maranhão, Pará e Amapá (Villwock et al 2005). Podemos citar dois estudos para o litoral amazônico: Rocha et al (2014), que estudaram a composição de gramíneas para savanas costeiras amazônicas e Rocha e Miranda (2014), que estudaram as comunidades de Poaceae nas savanas do estuário amazônico. No entanto, no perímetro que corresponde ao Estado do Maranhão, não havia sido realizado ainda nenhum estudo para esse grupo.…”