Seasonal variation in gas exchange by plants of Erythroxylum simonis Plowman

João Everthon Da Silva Ribeiro,Walter Esfrain Pereira,Sérgio De Faria Lopes,Manoel Bandeira De Albuquerque,Ana Jéssica Soares Barbosa

doi:10.1590/0102-33062017abb0240

João Everthon Da Silva Ribeiro, Walter Esfrain Pereira + Show 3 more

Open Access

https://doi.org/10.1590/0102-33062017abb0240

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Abstract

ABSTRACT Erythroxylum simonisis an understory species found in Northeast Brazil. Due to its shaded habitat,E. simonisis subjected to seasonal oscillations of the environment, to which it must respond ecophysiologically. The objective of this study was to evaluate the effects of seasonality on the ecophysiology ofE. simonis in a fragment of Seasonal Semideciduous Forest. Leaf area index, visible sky fraction and photosynthetically active radiation were measured for 10 individuals during the dry and rainy seasons. Soil moisture, temperature and monthly precipitation were measured, as well as photosynthetic rate, stomatal conductance, internal CO2concentration, transpiration, instantaneous water use efficiency, instantaneous carboxylation efficiency and chlorophyll content. Ecophysiological variables were correlated with environmental variables, with a greater association of rainfall and soil moisture with stomatal conductance, transpiration and photosynthetic rate, indicating that water availability has an effect on the ecophysiology ofE. simonis. With the exception of instantaneous carboxylation efficiency, gas exchange exhibited significant differences among the months studied, with the highest values being for months with greater water availability, thus showing that the ecophysiology of the species responds to seasonal changes throughout the year.

Highlights

Tropical forests are ecosystems of great importance and are known for their tremendous biodiversity, which is one of the factors that contribute to the great diversity of ecological niches therein (Gardner et al 2010)
Ecophysiological variables were correlated with environmental variables, with a greater association of rainfall and soil moisture with stomatal conductance, transpiration and photosynthetic rate, indicating that water availability has an effect on the ecophysiology of E. simonis
Along the main axis (PC1), the values of the eigenvectors of stomatal conductance and precipitation are positioned to the most extreme right, while Leaf area index (LAI) and Photosynthetically active radiation (PAR) are positioned to the left, which shows the separation of these two variables from the others analyzed (Fig. 3)

Summary

Introduction

Tropical forests are ecosystems of great importance and are known for their tremendous biodiversity, which is one of the factors that contribute to the great diversity of ecological niches therein (Gardner et al 2010). Among the diverse types of tropical forest are seasonal forests, which are characterized by two seasons: a dry season and a rainy season. In this type of vegetation, leaf abscission is frequently associated with the dry season (Pennington et al 2006), which may be directly related to the low rainfall rates during this period, resulting in greater water stress for the species (Braz et al 2000; Silvério & Lenza 2010; Rebelatto et al 2013). The effect of season on growth and development of forest species mainly impacts vegetation located in the understory, where young individuals of canopy tree species are located, including small trees that will never reach the canopy during their life cycle (Prado Júnior et al 2015), in addition to shrubs, palms, arborescent embryos, seedlings and herbs (Oliveira et al 2001).

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