Structural analysis of the vegetation on a highland granitic rock outcrop in Southeast Brazil

Abstract

-(Structural analysis of the vegetation on a highland granitic rock outcrop in Southeast Brazil). Granitic rock outcrops of the Brazilian southeast are either coastal or inland. The latter can often have high altitudes, such as in the summits of "Serra do Mar" and "Serra da Mantiqueira", where they are known as "Campos de Altitude". The landscape on these high altitude plateaux is often a mosaic of shrubs and treelets within a bunchgrass matrix, with sparse pteridophytes and other herbs, interspersed with variable extensions of rock outcrops. Despite the pervasiveness of rock outcrops in the Brazilian landscape, studies on the structural analysis of the vegetation on such formations are scarce. This study aimed to analyze the structure of the vegetation on a highland granitic rock outcrop in "Parque Estadual da Serra do Brigadeiro", state of Minas Gerais, Southeast Brazil (42°20' -42°40' S and 20°20' -21°00' W, 1,722 m of elevation ). Quantitative parameters of absolute and relative frequency and dominance (cover) were estimated. The group analysis used the Jaccard similarity index. Trilepis lhotzkiana, Panicum sp. 1, and Vellozia variegata presented the highest relative frequencies, relative dominances and importance values. These three species, along with Dyckia bracteata, Rhynchospora emaciate, and Tibouchina cf. manicata, represented 98.3% of the relative dominance. The remaining 1.7% referred to 22 remaining species. The distinction among quadrats within formed groups by cluster analysis was due to the great number of low frequency species.Key words -high altitude vegetation, photographic chart method, rock outcrop, "Parque Estadual da Serra do Brigadeiro", structural analysis RESUMO -(Análise estrutural da vegetação sobre um afloramento rochoso granítico de altitude no Parque Estadual da Serra do Brigadeiro, Minas Gerais, Brasil). Os afloramentos rochosos graníticos do sudeste brasileiro ocorrem no litoral ou no interior. Neste segundo caso, incluem-se os Campos de Altitude, como aqueles encontrados nos cumes das Serras do Mar e da Mantiqueira. A fisionomia mais freqüentemente encontrada nos platôs é composta de mosaicos de arbustos e arvoretas, inseridos em uma matriz de touceiras de gramíneas, com pteridófitas e outras ervas dispostas espaçadamente, além de extensões variáveis de afloramentos rochosos. Apesar de freqüentes na paisagem brasileira, são escassos os trabalhos de análise estrutural da vegetação sobre afloramentos rochosos. O objetivo deste trabalho foi analisar a estrutura da vegetação sobre um afloramento rochoso granítico de altitude no Parque Estadual da Serra do Brigadeiro, MG (42°20' -42°40' S e 20°20' -21°00' W, 1.722 m de altitude). Foram estimados os parâmetros quantitativos de freqüência e dominância (cobertura), absolutas e relativas. A análise de agrupamento utilizou o índice de similaridade do Jaccard. Trilepis lhotzchiana, Panicum sp. 1 e Vellozia variegata apresentaram as maiores freqüências relativas, dominâncias relativas e os maiores valores de importância. Essas trê...

Composição florística da vegetação altimontana do distrito de Monte Verde (Camanducaia, MG), Serra da Mantiqueira Meridional, Sudeste do Brasil

“…Em Monte Verde, os Afloramentos Rochosos estão envoltos por matriz florestal e observa-se a formação de um escrube pouco extenso nas suas bordas. Asteraceae, Cyperaceae, Melastomataceae, Orchidaceae, Poaceae, Polygalaceae e Rubiaceae estão entre as famílias mais ricas nos afloramentos rochosos imersos em formações florestais no Sudeste brasileiro (Meirelles et al 1999;Safford & Martinelli 2000;Caiafa & Silva 2007;Ribeiro et al 2007). Cyperaceae geralmente não é citada como uma das famílias mais ricas em afloramentos rochosos no Sudeste, entretanto espécies dessa família são citadas como as principais espécies formadoras das ilhas de vegetação sobre afloramentos graníticos e sobre nifelina-sienito no Sudeste do Brasil (Caiafa & Silva 2007;Medina et al 2006 (Burkart 1979;Azevedo 1981;Landrum 1984;Mentz & Oliveira 2004).…”

Upper montane grassland structure within six subranges of Serra do Mar, Southern Brazil

“…Therefore, further studies and surveys are required in order to obtain a more widely applicable ecological knowledge. However, we conducted a brief analysis relating to upper montane grasslands of the present study with other vegetation studies about altitude rocky outcrops in Serra da Mantiqueira (Southeastern Brazil) (Caiafa & Silva 2007, Ribeiro et al 2007, Tinti et al 2015 as well as two sites of Serra do Mar (Araras & Madalena) in the State of Rio de Janeiro (Meirelles et al 1999). We learned that neither of the species found in the upper montane grasslands within Serra do Mar in Paraná was found in these two areas in Rio de Janeiro.…”

“…Perhaps because such species might be more adapted to grasslands than rocky outcrops. Based on studies carried out at Serra da Mantiqueira only two species were found (Caiafa & Silva 2007) to approximately two dozen species (Tinti et al 2015) in common with the ones found within the subranges studied in Paraná, which in addition to the distances between them, may be related to the surrounding phytogeographic aspects. The floristic study reported by Tinti et al (2015) (Serra do Brigadeiro -Mantiqueira, in the State of Minas Gerais) is in alignment with the grasslands of our study, for instance, the following taxa: Achyrocline satureoides, Stevia clausseni, Gaultheria serrata, "Croton mullerianus"(Croton splendidus), Hesperozygis nitida, Lycopodium clavatum, Doryopteris crenulans and Galium hypocarpium.…”

“…The floristic study reported by Tinti et al (2015) (Serra do Brigadeiro -Mantiqueira, in the State of Minas Gerais) is in alignment with the grasslands of our study, for instance, the following taxa: Achyrocline satureoides, Stevia clausseni, Gaultheria serrata, "Croton mullerianus"(Croton splendidus), Hesperozygis nitida, Lycopodium clavatum, Doryopteris crenulans and Galium hypocarpium. Whereas, the phytosociological analysis by Caiafa & Silva (2007), shares only Esterhazya splendida, ranking in the twenty-fourth position in terms of structural importance value, in Serra da Mantiqueira (Minas Gerais) as well as the physiognomy dominated by Chusquea mimosa within Serra do Ibitiraquire (Serra do Mar) in Paraná.…”

“…Such pattern has been fairly well-known, in which habitats subjected to extreme environmental conditions such as Restingas (beach ridge vegetation), rupestrian vegetation and upper montane grasslands, tend to be dominated by one or a few species (Scarano 2002, Caiafa & Silva 2007. The greatest diversity detected in the grassy physiognomy within Serra do Ibitiraquire is mainly due to the high species richness, which is likely caused by increased sampling intensity related to its greater extension and diversity of environments as well as its greater altitudinal gradient.…”