Estratégias de aquisição e uso de nutrientes por plantas em gradientes de disponibilidade de luz e de fertilidade do solo na caatinga

Abstract

The functional strategies of plants, both above and belowground, reflect different ecological approachesto the acquisition and use of resources, and are analyzed by means of leaf and root functional traits. Thiswork aimed to investigate which functional strategies for nutrient absorption, taking into account bothautonomous absorption and symbiosis dependence, and nutrient use are presented by Caatingaherbaceous plants along a gradient of light availability and soil fertility. To this end, we analyzedattributes such as specific root length, root dry matter content, root tissue density, specific leaf area andleaf concentrations of macro- and micronutrients, as well as the influence of symbiotic interactions witharbuscular mycorrhizal fungi and dark septate endophyte and soil physicochemical parameters on thedistribution of these herbaceous plants along a gradient of light availability. The analysis of thefunctional strategies of Caatinga herbaceous plants in light and soil gradients shows that plants thatoccur in the sun exhibit conservative strategies, with a low concentration of leaf nutrients and greaterinvestment in roots to solubilize nutrients, while shadow plants follow an acquisitive strategy, with ahigher leaf content of P, N, Mg and K, favoring high rates of photosynthesis. At the edges, the acid pHand low iron availability lead to conservative adaptations in both the aerial and underground parts.Colonization by mycorrhizal fungi is widespread, while dark septate endophyte are also frequent,unrelated to soil organic matter, indicating coexistence without obvious competition. The negativerelationship between leaf phosphorus and soil phosphorus suggests limitations in the mobility of thisnutrient and interactions with nitrogen absorption. Therefore, Caatinga herbaceous plants investresources in specific strategies that allow them to deal with environmental challenges such as nutrientvariation and competition for light. These data provide theoretical support for initiatives to restoredegraded areas of the Caatinga.