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| Reis,Ana Maria S.; Araújo,Elcida L.; Ferraz,Elba Maria N.; Moura,Ariadne N.. |
| The influence of climatic variations on the herbaceous component of the "caatinga" vegetation was examined in the state of Pernambuco, Brazil. A total of 105 1 × 1 m-plots were established, of which 35 were in a level micro-habitat, 35 in a riparian micro-habitat, and 35 in a stony microhabitat. During two consecutive years all herbaceous plants in these plots were counted, measured (height and diameter), and collected for identification. The Shannon-Wiener diversity index and the equitability were calculated for each year, as well as the density, frequency, dominance, total basal area and importance index for each species. The total annual pluviometric was 819.5 and 448.8 mm in 2002 and 2003, respectively. The herbaceous flora in the study area was... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Caatinga; Herbaceous component; Phytosociology; Seasonal climate changes; Species richness. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042006000300017 |
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| Lira,Giulliari A. S. T.; Araújo,Elcida L.; Bittencourt-Oliveira,Maria Do Carmo; Moura,Ariadne N.. |
| The present study reports the phytoplankton abundance, dominance and co-existence relationships in the eutrophic Carpina reservoir, Pernambuco, Brazil. Sampling was carried out at six different depths bimonthly at a single reservoir spanning two climatic periods: dry season (January, September, and November 2006) and rainy season (March, May, and July 2006). Density, abundance, dominance, specific diversity and equitability of the community were determined, along with chlorophyll a, and physical and chemical variables of the environment. Eight species were considered abundant, and their densities corresponded to more than 90% of the total phytoplankton community quantified. Cyanobacteria represented more than 80% of this density. Cylindrospermopsis... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Carpina reservoir; Cylindrospermopsis raciborskii; Cyanobacteria; Limnological characteristics; Phytoplankton structure; Vertical distribution. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000400018 |
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| Dantas,Ênio W.; Moura,Ariadne N.; Bittencourt-Oliveira,Maria do Carmo. |
| This study investigated the dynamics of cyanobacteria in two deep, eutrophic reservoirs in a semi-arid region of Brazil during periods of stratification and destratification. Four collections were carried out at each reservoir at two depths at three-month intervals. The following abiotic variables were analyzed: water temperature, dissolved oxygen, pH, turbidity, water transparency, total phosphorus, total dissolved phosphorus, orthophosphate and total nitrogen. Phytoplankton density was quantified for the determination of the biomass of cyanobacteria. The data were analyzed using CCA. Higher mean phytoplankton biomass values (29.8 mm³.L-1) occurred in the period of thermal stratification. A greater similarity in the phytoplankton communities also occurred... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Biomass; Cylindrospermopsis raciborskii; Seasonal dynaics; Theral pattern. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000400019 |
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