Relação entre a vegetação e as propriedades do solo em áreas de campo limpo úmido no Parque Nacional de Sete Cidades, Piauí, Brasil

Abstract

ResumoO objetivo desse estudo foi avaliar a estrutura da camada herbáceo-subarbustiva em comunidades de campo limpo no Parque Nacional de Sete Cidades localizado no Piauí, e a sua relação com as variáveis edáficas e espaciais das áreas. A amostragem da vegetação foi realizada no final da estação chuvosa/início da seca, através do método de interseção na linha, para determinar a composição e a cobertura linear das espécies. Dezessete linhas de 10 m, subdivididas em seções de 1 m, foram distribuídas em seis áreas distintas. Amostras de solo (0-20 cm) foram coletadas para análises químicas e texturais. Foram amostrados 71 táxons relacionados a 46 gêneros e 25 famílias. A análise de correspondência canônica (CCA) separou as linhas amostradas em três grupos, associados as propriedades texturais e químicas do solos, que coincidiram com as áreas mais similares. O procedimento de permutação com múltiplas respostas (MRPP) detectou diferenças significativas entre os grupos da CCA. As variáveis ambientais mais fortemente correlacionadas foram Cu, Fe, saturação de alumínio, silte, Zn, saturação de bases e areia, explicando 37,9% da variação dos dados. A distância espacial entre as linhas foi responsável por 16,8% da variação explicada. A distribuição dos campos úmidos no Parque parece estar determinada pelos gradientes de textura e fertilidade dos solos. Palavras-chave: cerrado, estrato herbáceo, método de interseção na linha, variáveis ambientais. AbstractVariations in soil proprieties seem to determine the spatial distribution of plant communities in the moist grassland. The aim of this study was to evaluate the relationship between the floristic composition and structure of the herbaceous-subshrub layer and soil and spatial variables in grassland communities in the National Park of Sete Cidades, Piauí, Brazil. The composition and linear coverage of the species were assessed by the lineintercept method. A total of 17 lines of 10 m, subdivided in sections of 1 m, were distributed into six distinct areas. Soil samples were collected for chemical and textural analysis. We sampled 71 taxa in 46 genera and 25 families. Through canonical correspondence analysis (CCA) the lines sampled were separated into three groups, associated with the textural and chemical soil properties, which coincided with the most similar sites. The multi-response permutation procedures (MRPP) found significant differences between groups of the CCA. The environmental variables most strongly correlated were Cu, Fe, aluminum saturation, silt, Zn, base saturation and sand, accounting for 37.9% of data variation. The spatial distance between the lines accounted for 16.8% of the explained variance. The distribution of the wet grasslands in the park seems to be determined by texture and soil fertility gradients. Key words: cerrado, herbaceous layer, line-intercept method, environmental variables Relação entre a vegetação e as propriedades do solo em áreas de campo limpo úmido no Parque Nacional de Sete Cidades, Piauí, Brasil

Temporal change in species and functional plant traits in the moist grassland on the Sete Cidades National Park, Piauí, Brazil

“…The similarity between the inventories for the total area, as well as between the drier communities (fragments one, two, four and five) and the wetter ones (three and six) (Mendes et al, 2012), were evaluated by the Chao estimator for Sørensen index, which reduces under sampling bias by estimating and compensating for the effects of unseen, shared species (Chao et al, 2005). We calculated the Chao-Sørensen index from the 95% confidence intervals (95% CI) using the EstimateS 8.2 software (Colwell, 2006).…”

“…In the areas of study they are strongly acidic (pH ranging from 3.8 to 4.2), with high levels of aluminum (0.2 to 1.0 cmolc.dm -3 ), low levels of macronutrients, especially Ca and Mg, which amounted to around 0.3 cmolc.dm -3 and high iron content (Mendes et al, 2012). We selected two subtypes of moist grassland communities in the areas studied in 2007 based on the duration of flooding (Mendes et al, 2012) …”

“…The herbaceous-shrub vegetation was sampled using the line transect interception method (Canfield, 1941). The 10 m transects were distributed into six fragments with different sizes (1.2 to 19.2 ha) and different soil moisture content (Mendes et al, 2012). Each transect was subdivided in 1 m sections with iron rods.…”

Chloroplast diversity of Casearia grandiflora in the Cerrado of Piauí State

“…Parque Nacional de Sete Cidades is a conservation unit established in 1961, located between Brasileira and Piracuruca cities in northern Piauí State (Mendes et al, 2012). Eighty individuals were collected, including two populations.…”

“…It is a focal for studies, particularly the long-term ones, because it is a federal conservation unit of integral protection (Matos and Felfili, 2010). The vegetation of the park is characterized by great diversity of communities, occurring in mosaics included in areas of Cerrado and Cerrado/Caatinga ecotones (Mendes et al, 2012).…”