Ajustes funcionais de uma erva de sub-bosque para sobreviver à variação na disponibilidade de água em uma floresta de terra firme da Amazônia

Abstract

To thrive in a wide range of environments faced by individuals of widely distributed species may demand the ability to adjust their functional trait. Here, we ask whether the intraspecific variation in the functional traits of an Amazonian ground-herb species with wide regional and local distribution (Ischnosiphon arouma, Marantaceae) is linked to the hydrological variation on a local scale. The research was carried out in an Amazonian terra-firme forest, with high topographic variation. We measured traits related to the acquisition and conservation of resources such as leaf thickness (LT), specific leaf area (SLA), leaf dry matter content (LDMC); and anatomical traits of the leaf and plant growth in individuals well distributed along the topography. As a proxy for plant access to water, we used the elevation of the terrain. We found an association between most of the functional traits and the hydrological gradient. SLA and number of stems decreased with elevation, while LDMC and LT showed the opposite pattern. Variation in plant height and stomata length or density were not associated with the hydrological gradient. Therefore, there are intraspecific adjustments along the spectrum of plant economy, with an acquisition tendency in the valleys, indicating greater growth capacity, while in the plateaus a pattern of conservation of the structure is revealed, given the greater LT and LDMC values. This ability to adjust at a local scale can allow for the wide distribution of species in Amazonia and it can provide the necessary capacity to adjust to climate change.