Instantaneously measured traits may detect non-plastic ecophysiological performances in response to drought, explaining
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ORIGINAL PAPER
Instantaneously measured traits may detect non-plastic ecophysiological performances in response to drought, explaining distributions of Styrax species in the Cerrado Eduardo B. da Veiga • Gustavo Habermann
Received: 4 October 2012 / Revised: 17 July 2013 / Accepted: 26 July 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract We analyzed the differences between irrigated and non-irrigated plants of three congeneric Styrax species that present distinct distribution patterns in the physiognomies of the Cerrado vegetation in Brazil. Styrax ferrugineus showed a stomatal conductance (gs) unresponsive to soil water deficit in potted plants. This may explain the high gas exchange and photochemical efficiency found in this species, which is well adapted to the Cerrado sensu stricto (s. str.), a savanna-type vegetation. S. camporum, which is widely distributed in the Cerrado sensu lato (s. l.) areas, was the only species that exhibited increased intrinsic water use efficiency on the days of maximum water deficit. This result distinguishes S. camporum from S. pohlii, which is a forest species, since the gs of both species decreased during the days of maximum water stress. In contrast to other studies, we propose that instantaneously measured traits, such as leaf gas exchange rates and chlorophyll fluorescence, may be used to detect non-plastic performances in response to environmental stress, helping explain distinct geographical distributions of congeneric species in the Cerrado vegetation. Keywords Brazilian savanna Chlorophyll fluorescence Leaf gas exchange Leaf water potential Semi-controlled conditions
Communicated by A. Braeuning. E. B. da Veiga G. Habermann (&) Departamento de Botaˆnica, Instituto de Biocieˆncias, Univ Estadual Paulista (UNESP), Av. 24-A 1515, Rio Claro, SP 13506-900, Brazil e-mail: [email protected]
Introduction The Brazilian savanna or Cerrado comprises forests, savannas and grasslands (Kanegae et al. 2000; Ferreira et al. 2003). Low sunlight and relatively high soil water concentration are observed in forests (Kissmann et al. 2012), whereas the opposite is noticed in savanna-type physiognomies (Habermann et al. 2011). Therefore, sunlight and water in the soil are believed to influence the species distribution between Cerrado physiognomies. Changes in the availability of such resources are accompanied by adjustments to the photosynthetic apparatus (Franco and Lu¨ttge 2002), the functioning of which may be influenced by stomatal conductance (gs) (Habermann et al. 2008), and biochemical and photochemical reactions (Paulilo et al. 1994; Franco et al. 2007; Feistler and Habermann 2012). The rainy (Nov–Mar) and dry (May–Sep) seasons (Ferreira et al. 2003) seem to functionally influence the Cerrado vegetation (Franco 1998), as species occurring in distinct physiognomies may show specific adaptations. Comparisons between soil (Wsoil) and leaf (Ww) water potentials (Franco 1998; Hao et al. 2008) demonstrated that woody species from the Cerrado sensu stricto (s. str.), a sav
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