Estratégias morfofuncionais foliares de espécies anuais em dunas costeiras no litoral cearense

Abstract

Coastal dunes are dynamic and environmentally extreme ecosystems, characterized by sandy soils, high drainage, water deficit, salinity, strong winds and high irradiance, which impose multiple stresses on plants and make this environment a suitable model for investigating leaf strategies associated with stress tolerance. This study aimed to understand how morphological, anatomical and histochemical leaf traits of annual species from coastal dunes in Ceará are related to tolerance to multiple stresses and to the maintenance of these ecosystems. Twelve annual species were collected in semi-mobile and fixed dunes in the municipality of São Gonçalo do Amarante, Ceará, and analyzed through external morphological characterization, leaf area measurements, anatomical description in transverse and paradermal sections, and histochemical tests to detect hydrophilic, lipophilic and protein compounds. Traits such as leaf area, lamina thickness, epidermis, outer periclinal wall, cuticle, mesophyll organization, stomatal density, guard cell length, leaf vein density and the presence of trichomes and idioblasts were quantified and evaluated using descriptive statistics, tests for comparison among species, comparisons between leaf surfaces and correlation analyses. There was wide interspecific variation in leaf area and leaf thickness, with a predominance of small to medium leaves and structurally robust laminae, a mostly dorsiventral mesophyll, and an adaxial epidermis generally thicker than the abaxial one. The outer periclinal wall, together with the presence of mucilaginous idioblasts and cells containing phenolic compounds, indicated structural reinforcement and greater water-retention capacity in several species, while stomatal density varied widely and was inversely related to guard cell length. Taken together, these results indicate that the studied species share a set of traits compatible with predominantly conservative water‐use strategies, while exhibiting distinct functional combinations that allow different ways of tolerating stress and contributing to the persistence of annual vegetation in coastal dunes of Ceará.