SummaryLeaf water isotopic composition is imprinted in several biomarkers of interest and it is imperative that we understand the isotopic enrichment of leaf water. Here, we test the effect of stomatal density and leaf water content on the oxygen isotopic composition of leaf water in transgenic Arabidopsis plants expressing different stomatal densities, and several other species showing a range of stomatal density.We grew Arabidopsis plants hydroponically and collected other species in the field. Stomatal density and leaf water content were determined for each plant. We measured transpiration and extracted leaf water for isotopic determination. Using these measurements and the current leaf water isotope model, we calculated several of the parameters related to leaf water isotopic enrichment.High stomatal density promoted leaf water isotope enrichment. No conclusion, however, can be drawn regarding the effect of leaf water content on leaf water isotope enrichment. Factors such as transpiration might mask the effect of stomatal density on leaf water isotopic enrichment.We propose a method by which stomatal density can be incorporated in the current Peclet model of leaf water isotope enrichment. These findings have important applications in the use of plant-based metabolic proxies in paleoclimate studies.

RESUMOEsse estudo avaliou comparativamente os parâmetros fitossociológicos da regeneração natural e da vegetação arbórea em dois manguezais distintos no Estado do Paraná, um pertencente à Baía de Paranaguá (manguezal de Antonina) e outro à Baía de Guaratuba (manguezal de Guaratuba). Em cada área, três subáreas foram marcadas e amostradas cinco parcelas de 10 x 10 m para avaliação do componente arbóreo e quinze subparcelas de 1 x 1 m para avaliação da regeneração natural. Avicennia schaueriana, Rhizophora mangle e Laguncularia racemosa exibiram domínio e densidade relativa distintos entre as áreas. Manguezais de Antonina e Guaratuba diferiram tanto na estrutura da regeneração natural como no componente arbóreo. A Análise de Coordenadas Principais (PCoA) mostrou que as diferenças entre as áreas em relação às variáveis abióticas do solo estão fortemente relacionadas com os parâmetros estruturais do componente arbóreo dos manguezais. Os fatores edáficos dos manguezais têm grande importância na separação entre as áreas, já que reflete na capacidade de adaptação das plantas. Palavras-chave: fitossociologia; mangue; salinidade; solo. ABSTRACTWe analyzed the structures of two mangrove forests of Paraná (Brazil) (Antonina Bay and Guaratuba Bay), considering adult trees and regeneration component. In each area, we marked three sub-areas and sampled five plots of 10 x 10 m, equivalent to 0.05 ha to adults trees and fifteen 1 x 1m sub-plots to assess the regeneration component. Avicennia schaueriana, Rhizophora mangle and Laguncularia racemosa exhibited distinct dominance and relative density between the areas. Mangroves of Antonina and Guaratuba differed both in the structure of natural regeneration as the tree component. The Principal Coordinates Analysis (PCoA) show that differences between areas in relation to abiotic variables of soil are strongly related to the structural parameters of trees. The different types of mangrove soil are the most significant factor in the differentiation between the mangrove areas since influences the salinity values and consequent adaptability of plants.

Sclerophylly, a morphological trait that defines coriaceous and hard leaves, is presently accepted as a non-specific response to environments with acting multiple stresses. In mangroves, features such as flooded and unconsolidated soil, low availability of oxygen, and high salinity characterize this stressful environment. From 2 mangroves areas in the coast of Paraná state, leaves of 3 species (Rhizophora mangle, Laguncularia racemosa and Avicennia schaueriana) were collected and analyzed nutritionally and morphologically. Sclerophylly indices (Rizzini index and specific leaf area) indicated that all species are sclerophyllous. Considering nutritional and morphological traits, only some of them suggest sclerophylly, such as total leaf thickness in all species, the presence of a subepidermal layer in Rhizophora mangle and Avicennia schaueriana and sclereids in Rhizophora mangle. Comparatively, leaves presented different degrees of sclerophylly, in the following order: R. mangle > L. racemosa > A. schaueriana, considering all characteristics analyzed. This gradient of sclerophylly appears to be consequence of different strategies developed by each species in response to the stressful abiotic conditions of mangroves, especially the mechanisms for salinity tolerance.

The objective of this study was to understand the different morpho-physiological strategies of Ligustrum lucidum, an invasive species occurring in Brazilian forest fragments under heterogeneous light conditions. Ten individuals of L. lucidum were selected and evaluated for morphological of the leaves and physiological traits. For morphological parameters were evaluated: length, width, area, angle, petiole length, dried mass, total thickness, palisade parenchyma and spongy parenchyma thickness, abaxial and adaxial epidermis thickness, stomata density, leaf density and specific leaf area. The physiological traits were vapor-pressure deficit, assimilation rate, CO 2 substomata concentration, intrinsic water-use efficiency, transpiration rate and stomatal conductance. All the physiological variables and most morphological variables presented significant differences between light conditions. Phenotypic plasticity indexes were not high as expected. However, phenotypic integration among the morphological and physiological attributes appeared to explain better these results, as observed on the relationship among assimilation rates, palisade parenchyma thickness and SLA. Phenotypic integration could increase the species adaptive responses efficiency, making it more competitive to occupy and to establish in new niches.

Respostas adaptativas à interação de fatores abióticos que atuam em diferentes escalas espaciais e temporais podem reletir na distribuição das espécies, em decorrência de sua interação com o ambiente. Este estudo teve por objetivo veriicar as diferenças na estrutura dos indivíduos entre populações de Laguncularia racemosa (L.) C. F. Gaertn. (Combretaceae) distribuídas em áreas de manguezal e de transição manguezal e restinga, utilizando características morfológicas foliares e arquitetura da planta. Foram analisadas varáveis ambientais, como nutrientes do solo e teor de salinidade. A área de transição apresentou menor salinidade da água intersticial e pH do solo, provavelmente em decorrência dos altos índices de alumínio. Indivíduos de L. racemosa da área de manguezal apresentaram folhas maiores que a população da área de transição, com maior área foliar, área especíica foliar, densidade foliar e menor volume foliar. No manguezal, indivíduos de L. racemosa apresentaram maior altura e diâmetro basal do tronco e menor densidade de copa e percentual de folhas herbivoradas, porém, maior número de folhas senescentes. Tais resultados possivelmente relacionam-se com as contrastantes condições ambientais e com expressivas diferenças na salinidade da água e nos nutrientes dos solos.