Coordenação funcional e fenológica de espécies lenhosas de uma floresta ripária na caatinga

Abstract

Knowledge about plant phenology and the identification of functional groups are important for a better understanding of the functioning of ecosystems, including their ecology, dynamics and evolution. The phenology of plants from seasonally dry tropical forests is coordinated by the abiotic factors and the functional morphological traits of the species, especially those related to the water relations of the plant. However, few ecosystems have been investigated in this regard, as is the case of riparian forests in semi-arid environments. We aim was to evaluate the influence of abiotic variables and morphological functional characteristics on the phenology and formation of the functional groups of woody species of a riparian forest. Were measured and analyzed functional traits of vegetative phenology, leaf traits (specific leaf area, leaf area, leaf thickness and leaf dry-matter content), wood density and saturated capacity of stem water and their relationships with the soil water availability and other abiotic variables. Functional traits were ordered using the Bray-Curtis index and then a multidimensional scaling analysis was performed to identify the main functional groups. A principal component analysis was performed to identify which variables had the greatest influence on the species and a canonical correspondence analysis to verify which abiotic factors influenced the phenophase trigger in each group. The functional morphological traits influenced the formation of the groups and the phenological behavior of the species. Three functional groups were identified: deciduous species of high wood density, deciduous low wood density and non-deciduous species (semideciduous and evergreen). The species of each group exhibited strong relationships among themselves in leaf area traits, wood density, amount of stem water and specific leaf area. Deciduous and semideciduous plants showed strong dependence on the abiotic factors associated with precipitation and temperature, while the evergreen species showed a strong dependence on the vapor pressure deficit for the phenophases to be triggered. These results reinforce the importance of studies that relate functional traits to phenology and abiotic factors, allowing advances in the understanding of plant strategies of seasonally dry environments.