Características estomáticas de pares congenéricos de cerrado e mata de galeria crescendo numa região transicional no Brasil central

Abstract

RESUMO -(Características estomáticas de pares congenéricos de cerrado e mata de galeria crescendo numa região transicional no Brasil Central). Em áreas protegidas do fogo, espécies arbóreas predominantemente florestais conseguem se estabelecer no cerrado e crescer lado a lado com espécies do mesmo gênero que são características destas formações savânicas. Devido às condições ambientais diferenciadas encontradas nas formações de cerrado e de mata, estas espécies congenéricas podem se comportar como grupos funcionais distintos. Neste trabalho foi realizado um estudo comparativo da anatomia dos estômatos e da condutância estomática e taxas de transpiração foliar em 10 pares de espécies congenéricas do cerrado e de mata de galeria e das relações entre as características estomáticas selecionadas e a condutância estomática, já que a morfologia dos estômatos e sua densidade afetam a área para difusão dos gases e sua trajetória através dos poros estomáticos. Cada par foi de uma família diferente. Para a maioria das espécies, a área do poro estomático foi o fator de maior influencia no processo de trocas gasosas, pela sua correlação com a condutância estomática, enquanto a densidade estomática mostrou uma correlação negativa significativa tanto com o comprimento da célula-guarda quanto com a área do poro estomático. As espécies do cerrado apresentaram valores significativamente maiores do comprimento da célula-guarda e do poro estomático. No entanto, para a maioria dos outros parâmetros estomáticos examinados, a maior parte da variação pode ser atribuída a diferenças entre os gêneros, sendo que a variação entre as espécies dos dois ambientes parece ser um produto da historia evolutiva de cada grupo e não reflete uma especialização ao ambiente de cerrado ou de mata de galeria. Palavras-chave: condutância estomática, estômato, poro estomático, transpiraçãoABSTRACT -(Stomatal traits of cerrado and gallery forest congeneric pairs growing in a transitional region in Central Brazil). In fireprotected sites of Central Brazil, forest trees can establish in the neighbouring savanna and grow side by side with cerrado trees of the same genera. Because of the large differences in their native environment, the cerrado and forest species may represent two distinct functional types. In this study we performed a comparative study of stomata anatomical characteristics, stomatal conductance and transpiration of 10 congeneric species pairs of cerrado and gallery forest species. Each pair was from a different family. Because stomatal anatomy and density affect the area and the path for gas diffusion through the stomatal pores, we also assessed possible relationships among the selected stomata traits and stomatal conductance. The area of the stomatal pore was the anatomical trait with the largest influence on gas exchange. Increases in pore area were correlated with an increase in stomatal conductance for most species. On the other hand, stomatal density was negatively correlated with both the length of the guard-cell and the area of the sto...

Structural and functional leaf traits of two Gochnatia species from distinct growth forms in a sclerophyll forest site in Southeastern Brazil

“…The values of stomatal frequency were high for both species and within the range reported for other "Cerrado" species (Rossatto et al 2009a). Studies about the patterns of stomatal density suggest high stomata densities in leaves subjected to high light intensities and/or low water availability (Pearce et al 2006) are factors associated with "Cerrado" vegetation and also the forest canopy.…”

“…We observed that the tree (G. polymorpha) had a greater number of sclerophyllous leaf traits, which are normally reported for woody, "Cerrado" species. These traits include smaller and thicker leaves, well developed parenchyma (Bieras & Sajo 2009), high stomatal density (Rossatto et al 2009a), higher photosynthetic rates (A area ) and lower values of specific leaf area (Rossatto et al 2009b). On the other hand, the shrub (G. barrosii) presented more mesophytic leaf traits, bigger and thinner leaves, higher values of specific leaf area and lower photosynthetic rates (A area ), which are reported for woody species that grow in lower light environments (Sefton et al 2002;Dahlgren et al 2006).…”

“…The presence of stomata on both leaf surfaces can be variable in Asteraceae (Breitwieser 1993;Milan et al 2006). The presence of amphistomatic leaves is variable also among "Cerrado" species (Morretes 1969;Elias et al 2003;Rossatto et al 2009a), despite that the general pattern reported for plants from this vegetation is hypostomatic leaves (Bieras & Sajo 2009). Stomata size was variable and the guard cell length of G. barrosii stomata was shorter.…”

“…Stomata size was variable and the guard cell length of G. barrosii stomata was shorter. Guard cell length is important because it can influence the pattern of stomatal frequency and stomatal conductance (Hetherington & Woodward 2003;Rossatto et al 2009a) because smaller stomata are more responsive to environmental changes (Hetherington & Woodward 2003;Galmes et al 2007).…”

Essential oils in aerial parts of Myrcia tomentosa: composition and variability

“…Within this genus, Myrcia tomentosa, popularly known as "goiababrava", can be found from Panama, northern Venezuela and Guyana to southeast Brazil (McVaugh, 1969) and is often cited in works on the flora, phytosociology and characterization of the Savanna/Cerrado (Mahmoud et al, 2003;Teixeira et al, 2004;Morais & Lombardi, 2006). However, few works report pharmacognostic or phytochemical studies for this species (Dianese et al, 1993;Cardoso & Sajo, 2006;Rossatto et al, 2009, Cardoso et al, 2009, and no reports have been found concerning its popular use.…”