What triggers phenological events in plants under seasonal environments? A study with phylogenetically related plant species in sympatry

Abstract

In this study, we evaluated variation in vegetative and reproductive phenological events of four phylogenetically related plant species subjected to a seasonal environment. To this aim, we sampled 15 individuals of each plant species every fortnight for one year, between January and December of 2017. To assess when a given phenophase occurred more intensely in the population, the Fournier intensity index was used and the synchrony of individuals of the sample in a given phenological event was estimated using the activity index. The Rayleigh (Z) test was used to determine whether the phenological events have seasonal distribution. The relationship of abiotic factors (photoperiod, precipitation, relative humidity and temperature) with the intensity of phenophases was evaluated for each plant species using generalized linear models (GLMs). The phenophases of all plants showed a seasonal distribution pattern, as well as variation in synchrony of phenophases and specific sets of abiotic factors significantly influenced their phenophases. New leaves, for example, were produced throughout the seasons, with intense leaf fall in the dry season. Flowering periods, on the other hand, did not overlap. Indeed, species exhibited sequential flowering and asynchronous flowering among individuals. Our results suggest that the phenological patterns of four sympatric plant species are directly linked to climatic variables, but different abiotic factors affected different phenophases.

Lessons from a tropical deciduous shrub species: leaf fall can play a more important role than rain in leaf budding

“…The flowers produce up to four-winged samara seeds (Mamede 1987). This species is classified as brevideciduous, losing all its leaves in the dry season for a period of up to 21 days (Pereira et al 2022).…”

“…In the Cerrado, the sequential chaining of phenological events during the dry season is a pattern observed in many plant species (Pereira et al 2022). In this season, many plants completely lose their leaves, and soon after deciduous, there is an expressive production of leaf buds (Araújo and Haridasan 2007;Pereira et al 2022).…”

“…With reduced precipitation and humidity, leaf fall can help conserve water, preventing the plant's vital activities from being compromised in the dry season (Goldstein et al 2008). Thus, as a result of leaf fall, rehydration promotes adjustments in plant water demand and supply, which are regulated by reducing leaf area, transpiration, increasing root system depth, and internal water reservoir (Scholz et al 2002), which guarantees the subsequent opening of leaf buds and flower buds (Pereira et al 2022).…”

“…Leaf bud production is linked to a wide range of adaptive responses to seasonal stresses (Pereira et al 2022). The development of young leaves in the dry season minimizes photosynthetic losses in this period of low light, showing higher efficiency at the beginning of the rainy season of high light, when mature leaves will have their photosynthetic apparatus developed, providing the energy needed for the subsequent peak flowering and fruiting (Goldstein et al 2008).…”

“…Knowledge of seasonal plant variations has been considered essential for the study of the ecology and evolution of the Cerrado and for understanding the spatiotemporal organization of available resources (Pereira et al 2022). In the tropics, climate change has been causing variations in the intensity of abiotic factors (for example, changes in the amount of rainfall, Mendoza et al 2017), changing the seasonal rhythms of species by affecting the sequential triggering of phenological events and, consequently, the plant development (Vilela et al 2017) and community dynamics (Fourcade et al 2021).…”