ABSTRACT Plant-herbivore interactions have directed the evolution of defense mechanisms in plants, which can vary intraspecifically according to environmental quality. This study evaluated variation in the production of antiherbivory defenses in plant species distributed along an environmental gradient of restinga. The study was performed in Parque Estadual Acaraí, state of Santa Catarina, Brazil. Three species of four plant formations with different abiotic conditions were selected for study. Specific leaf area; water, nitrogen and carbon content; and presence of phenols, tannins, lignin and alkaloids, were evaluated in leaves of ten plants per species per plant formation. The results indicated that Symphyopappus casarettoi possesses Low Nutritional Quality Syndrome, characterized by low specific leaf area, presence of secondary metabolites and low nitrogen content. Dodonaea viscosa and Varronia curassavica possess Nutrition and Defense Syndrome, characterized by a balance between nutritional quality (high nitrogen content and lower C:N ratio) and protection (greater thickness of leaves and higher density of trichomes). The results did not confirm the Resource Availability Hypothesis. The absence of a pattern in antiherbivory response due to the environmental gradient may indicate that the investment in defense by plants is not unidirectional and that certain morpho-anatomical attributes are typically related to conservation of resources.

RESUMO As espécies do subosque são adaptadas à condição de sombreamento imposta pelo dossel. O presente estudo caracterizou, por meio de atributos foliares, as estratégias utilizadas por diferentes espécies de subosque. O estudo foi realizado no Jardim Botânico da Universidade da Região de Joinville, SC, Brasil. Foram selecionadas sete espécies ciófitas. De cada espécie foram selecionados cinco indivíduos, dos quais 25 folhas foram coletadas para análise morfoanatômica e de teor de clorofila. A intensidade luminosa incidente sobre cada espécime foi medida. Os resultados confirmaram o alto grau de sombreamento das plantas em subosque. A razão clorofila a/b foi >1 e, portanto, contrária a esperada. Os testes estatísticos evidenciaram a existência de padrões de resposta ao sombreamento, caracterizados morfologicamente pela massa fresca, área foliar, comprimento e largura do limbo e área específica foliar e, anatomicamente, pela espessura do parênquima lacunoso. A convergência destes atributos está relacionada ao maior aproveitamento da luz que atinge o subosques.

ABSTRACT Understory species are adapted to shade condition imposed by the canopy. This study characterized, by means of leaf attributes, the strategies used by different species of understory. The study was conducted at the Botanical Garden of the University of the Region of Joinville, Santa Catarina State, Brazil. Seven shade species were selected. Of each species, five individuals were selected and 25 leaves were collected for morphological and anatomical analysis and chlorophyll content. The incident light intensity on each specimen was measured. The results confirmed the high degree of shading in understory plants. The ratio chlorophyll a/b was >1 and therefore contrary to expected. Statistical tests showed the existence of patterns of response to shading, morphologically characterized by fresh weight, leaf area, length and width of the blade and leaf specific area and, anatomically, the thickness of the spongy parenchyma. The convergence of these attributes is associated with greater use of light that reaches the understory.

ABSTRACT In ombrophilous forests, light stratification provokes different adjustments by plants for better use of the environmental conditions of each stratum. Among the morphological traits that vary with strata, the presence of bundle sheath extensions (BSEs) is related to water transport, photosynthesis, and leaf mechanical support and classifies leaves as homobaric or heterobaric. This study analyzed the proportion of these types of leaves in a Lowland Ombrophilous Dense Forest (LLODF) and a Mixed Ombrophilous Forest (MOF), and among the strata of each forest type. The morphological leaf traits of 89 LLODF tree species and 57 MOF tree species were examined. The proportion of homobaric and heterobaric leaves did not differ between forests. However, in both forest types, the distribution of species with heterobaric or homobaric leaves depended on strata, with heterobaric species occurring mainly in higher strata, and homobaric species in lower strata. Thus, light stratification acts as an ecological filter on the composition of the vegetation of these forests, favoring heterobaric species in places with higher light intensity and temperature, such as the highest strata of canopy. On the other hand, homobaric species are more frequent in lower strata, where light is less available and humidity higher.