De maneira geral, as atividades humanas trazem reflexos imediatos à paisagem. Nesse sentido, paisagem urbana pode ser interpretada como o resultado das ações do homem nesse espaço. De forma genérica, são subdivididas em naturais e antropizadas, em que essa classificação considera a origem de seus elementos constituintes (HARDT; HARDT, 2007
AimWe evaluated different facets of beta diversity (taxonomic, phylogenetic and functional), and its components (spatial turnover and nestedness), of a stream macroalgal metacommunity, as well as the effect of local environmental variables, types of biome and spatial factors on these facets and components.LocationTen natural areas of southern Brazil, covering the main biomes represented in the region.TaxonStream macroalgae.MethodsWe analysed a macroalgal data set collected in 105 stream segments using a dissimilarity partitioning approach to decompose total beta diversity into spatial turnover and nestedness components. Furthermore, we assessed the effects of local environmental variables, biome type and spatial factors on beta diversity components by performing distance‐based redundancy analysis (db‐RDA), and its partial version (db‐pRDA). Taxonomic data were tabulated considering four different species incidence matrices: total macroalgae; only green algae; only red algae and only cyanobacteria.ResultsFor taxonomic and phylogenetic facets, very high values of total beta diversity were found for all species incidence matrices, with spatial turnover (species replacement) accounting for almost all this diversity; nestedness had extremely low values. For functional diversity, total beta diversity was again high and spatial turnover was greater than nestedness, but nestedness (the tendency for less diverse locations to contain a subset of those in higher diversity locations) was considerably higher than that observed for taxonomic and phylogenetic facets. In regard to taxonomic and phylogenetic facets, total beta diversity and spatial turnover were, in general, significantly related to local environmental variables, biome type and spatial factors for total macroalgae and green algae, whereas they were significantly related to types of biome and space for red algae, and only to local environment for cyanobacteria.Main conclusionsOur results showed that spatial turnover was the main component of beta diversity, regardless of the facet and macroalgal species incidence matrix, and that the relative influence of local environmental variables, types of biome and spatial factors on the total beta diversity and its spatial turnover component can vary according to the facet considered and by algal group.
Recebido em 7/11/2006. Aceito em 11/06/2007 RESUMO -(Macroalgas de riachos da Serra da Prata, leste do Estado do Paraná, Sul do Brasil). Estudos florísticos das comunidades de macroalgas lóticas no Brasil são quase que exclusivamente baseadas em material do Estado de São Paulo. Informações sobre macroalgas de riachos são escassos no Estado do Paraná. Neste contexto, o presente trabalho teve como objetivo realizar o levantamento florístico das comunidades de macroalgas de riachos da Serra da Prata, uma área bem preservada e protegida de Floresta Ombrófila Densa. As amostras foram realizadas em 14 segmentos de riachos. O levantamento resultou na identificação de 19 táxons (15 infragenéricos, três genéricos e uma fase do ciclo de vida de Batrachospermum spp.), distribuídos em quatro divisões. Cyanophyta foi a divisão com maior número de representantes (58% das espécies) e Microcoleus subtorulosus Gomont ex Gomont foi a espécie mais bem distribuída. A maioria dos táxons encontrados (53%) são primeiros registros no Estado do Paraná, ao passo que alguns outros são considerados de ocorrência rara em riachos brasileiros. Estes resultados reforçam a importância e a necessidade de mais estudos florísticos e taxonômicos para que se amplie o conhecimento sobre a biodiversidade das comunidades de macroalgas de riacho no Brasil.
Palavras-chave: macroalgas, riachos, Cyanophyta, levantamento florísticoABSTRACT -(Stream macroalgae from Serra da Prata, eastern Paraná State, Southern Brazil). Studies of stream macroalgal communities in Brazil are almost exclusively based on data from São Paulo state. There are no extensive studies concerning stream macroalgae in Paraná state. In this context, the main objective of this study was to survey the flora of stream macroalgal communities in the Serra da Prata, a well-preserved and protected area of dense Atlantic rain forest. Sampling was carried out in 14 stream segments. The survey resulted in the identification of 19 taxa (15 infrageneric, three generic and one life cycle stage of Batrachospermum spp.), distributed in four divisions. Cyanophyta was the division with the highest number of taxa (58% of the species) and Microcoleus subtorulosus Gomont ex Gomont was the most widespread species. Most of the taxa identified (53%) were recorded for the first time in Paraná state, while others were considered rare in Brazilian streams. These results reinforce the importance and necessity of more floristic and taxonomic studies in order to increase our knowledge of stream macroalgal community biodiversity.
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