Acta Botanica Brasilica - 32(1): 1-11
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Acta Botanica Brasilica - 32(1): 1-11. January-March 2018. doi: 10.1590/0102-33062017abb0083 The infl uence of El Niño and edge eff ects on the reproductive phenology and fl oral visitors of Eschweilera tetrapetala Mori (Lecythidaceae), an endemic species of the Atlantic Forest of northeastern Brazil Isiara Silva Menezes1*, Ana Paula Lima do Couto-Santos2 and Ligia Silveira Funch3 Received: March 4, 2017 Accepted: August 15, 2017 . ABSTRACT We compared the reproductive phenology and fl oral visitors of Eschweilera tetrapetala growing along the edge and in the interior of a submontane forest in the Chapada Diamantina mountains, Bahia State, Brazil. We sought to determine if there were inter-annual diff erences in intensity and seasonality associated with environmental conditions, and if there were diff erences in fl oral visitors between the two environmental contexts. Phenological observations were performed for three years, and included the occurrence of an El Niño event. We applied circular statistics to detect seasonal trends, performed cross correlations between phenophases and climate, Kruskal-Wallis and Wilcoxon signed-rank tests for inter-annual variation, and the Wilcoxon-Mann-Whitney test for edge-interior diff erences in the species richness of fl oral visitors. We observed inter-annual variations in the intensity and seasonality of fl ower production that accompanied variations in rainfall, possibly associated with El Niño events. Floral visitor richness diff ered between the forest edge and interior, with seven species recorded for the interior and only one for the edge. Reduced fruit set was also observed at the forest edge. Th is study contributes to our understanding of the infl uence of El Niño and edge eff ects on the reproductive phenologies of tropical plants. Keywords: El Niño, Eschweilera tetrapetala, fl oral visitors, linear edge eff ects, phenology, precipitation, seasonality & Galleto 2004; Athayde & Morellato 2014). Reductions in Introduction the availability of abiotic resources such as water and soil nutrients in edge environments, for example, can limit Climate change, fragmentation, and loss of natural the fruiting rates of the plants there as compared to those areas are among the principal global threats to biodiversity growing in the forest interior (Dunley et al. 2009; Athayde (Klapwijk & Lewis 2008). Th ere is indisputable evidence & Morellato 2014). that edge eff ects resulting from forest fragmentation can Disturbances of plant-pollinator interactions can also modify the richness and abundance of tropical arboreal result from habitat fragmentation, and edge eff ects can species (e.g., Oliveira et al. 2004; Pires et al. 2014; Couto- further alter pollinator frequencies and abundances - and Santos et al. 2015). Th e phenology and reproductive success therefore pollination services - which can lead to drastic of plant species occurring near forest edges can be strongly eff ects on both pollinator and plant populations (Aizen aff ected by their diff erent environmental conditions (Aguilar & Feinsinger 1994; Franceschinelli et al. 2015). While 1 Programa de Pós-Graduação em Botânica, Laboratório Flora e Vegetação, Universidade Estadual de Feira de Santana, BR 116, Km 3, 44036-900, Feira de Santana, BA, Brazil 2 Departamento de Ciências Exatas e Naturais, Universidade Estadual do Sudoeste da Bahia, 45700-000, Itapetinga, BA, Brazil 3 Laboratório Flora e Vegetação, Departamento de Ciências Biológicas, Universidade Estadual de Feira de Santana, 44036-900, Feira de Santana, BA, Brazil * Corresponding author: [email protected] Acta Botanica Brasilica - 32(1): 1-11. January-March 2018 Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com.br Isiara Silva Menezes, Ana Paula Lima do Couto-Santos and Ligia Silveira Funch analyzing edge effects on the pollination and reproduction vulnerable (IUCN 2014) and negatively impacted mainly by of Meliaceae species in the Atlantic Forest of southeastern deforestation (CNCFLORA 2012). Menezes (2017) observed Brazil, Franceschinelli et al. (2015) observed that the that variables related to rainfall are the predictors that numbers of pollinators of the arboreal species examined most contribute to the construction of models regarding were greater in the forest interior than at the forest edge. the potential distribution of E. tetrapetala, with projected Another factor that can affect the reproductive reductions of 75 % of areas climatically adequate for its phenology of plants is climate change, which can alter growth by 2100. This projected reduction will be caused flowering seasons, with consequent effects on plant- by temperature increases and rainfall reductions in pollinator interactions (Hughes 2000; Hegland et al. 2009; northeastern Brazil, with consequent retractions of forested Scaven & Rafferty 2013). These effects on the phenological areas, including Atlantic Forest remnants (Torres & Marengo behaviors of plants and the possible loss of synchrony 2012; Colombo & Joly 2010). between mutualistic partners indicate the necessity of Numerous species of the Lecythidaceae occur in seasonal better understanding pollination mechanisms and how they environments with well-defined dry and rainy seasons, with are affected by the characteristics of plant and pollinator flowering occurring in the driest season and fruiting at the populations (Hegland et al. 2009). A large proportion of beginning of the period with the highest rainfall (Mori 1988). our knowledge about phenological responses to climatic This phenological reproductive pattern has been observed alterations has come from studies undertaken in temperate in E. ovata (Krause 2008), but not in Eschweilera tenuifolia regions in the northern hemisphere, where the effects (Maia & Piedade 2000). The genus Eschweilera is considered of global warming have been demonstrated in numerous hyperdominant and requires specific habitat characteristics studies (IPCC 2007). (Steege et al. 2013). Its pollination is associated with large Studies associating climate changes with alterations bees, following the general pattern of the family (Prance of phenological patterns at low latitudes in the southern 1976; Potascheff et al. 2013). hemisphere are still rare (Chuine 2010). As temperature In light of the restricted distribution of E. tetrapetala in variations are generally smaller in tropical and sub- seasonal submontane forests along the eastern edge of the tropical areas, rainfall has been identified as the principal Chapada Diamantina, where different population densities phenological driver, especially in seasonal environments are known to occur along forest edges and in the forest (Chambers et al. 2013). El Niño is a major source of climatic interior (Couto-Santos et al. 2015), and where variables variation in tropical South America, mainly affecting rainfall related to precipitation are the main predictors contributing regimes, with potential effects on phenological rhythms to models of its potential distribution (Menezes 2017), we (Malhi & Wright 2004; Wright & Calderon 2006). Multiple investigated the reproductive phenology E. tetrapetala and year studies of reproductive phenology can help identifying its floral visitors to address the following questions: i) Are the the effects of El Niño and their roles as phenological drivers flowering and fruiting phenophases of E. tetrapetala associated (Wright & Calderon 2006; Chambers et al. 2013). with environmental factors? ii) Are there differences in the The reproductive phenology and pollination of plants reproductive phenologies of individuals growing in the forest in the Chapada Diamantina Mountains (the northern interior and along the forest edge? iii) If such differences exist, extension of the Espinhaço Range in central-eastern do they affect fruit set in interior and edge sites? iv) Are there variations in the species richness of floral visitors to E. Brazil) have been the subject of several studies (Funch tetrapetala plants between interior and edge environments? v) et al. 2002; Ramos et al. 2005; Souza et al. 2012; Souza & Are there reproductive phenological variations associated with Funch 2016). The mountains at the eastern edge of the El Niño, as rainfall variations associated with that phenomenon Chapada Diamantina are covered by seasonal submontane are known to have important roles in regulating phenological forests (Atlantic Forest sensu lato) growing on deep latosols. rhythms (Wright & Calderon 2006)? Our main hypothesis was These forests have experienced profound physical impacts that the reproductive phenology of E. tetrapetala would be in the last 30 years (Oliveira-Filho & Fontes 2000; Funch affected by inter-annual variations in rainfall related to the El et al. 2008; Couto et al. 2011; Couto-Santos et al. 2015), Niño phenomenon and by forest edge-interior environmental including the installation of electrical transmission lines. contexts. Additionally, we hypothesize that the edge context Clearing during these installations has created extensive would negatively affect the richness of floral visitors of E. linear edges and caused strong impacts on the local floristic tetrapetala. composition and on the abundances of arboreal species, including Eschweilera tetrapetala (Lecythidaceae), which has been found to be more abundant in the forest interior than Materials and methods along artificial edges (Couto-Santos et al. 2015). The overall distribution of E. tetrapetala is quite Study area and the target species restricted, being endemic to the