Abstract
The genus Tabebuia is representative of the Cerrado biome, occurring in savanna and forest formations. These vegetation types are associated with distinct environmental conditions in terms of water availability, microclimate and soil properties. We compared morphological and physiological traits between Tabebuia aurea (Silva Manso) Benth. & Hook. f. ex S. Moore, which is typical of the savanna vegetation, and T. impetiginosa (Mart. ex DC.) Standl, which is commonly found in the gallery forests that occur along streams and rivers. Both were sampled in savanna conditions under full sun. The savanna species had higher values of leaf and petiole thickness, specific leaf mass, maximum CO2 assimilation on a leaf area basis, stomatal conductance, transpiration and in leaf concentration of carotenoids. The forest species stood out by higher values of specific leaf area, petiole length and of CO2 assimilation on a mass basis, parameters related to shade tolerance and higher growth rates. This functional distinction in a range of leaf traits that was maintained when both were naturally growing under similar environmental conditions, suggests that these are probably the result of differences in the evolutionary history of the two species in response to the contrasting environmental conditions in the typical habitats where they occur.
Highlights
The central part of Brazil is covered by a complex mosaic of grasslands, savanna and forests, known locally as the Cerrado, which originally covered an area of over 2 million km2
The most prominent vegetation types are the cerrado sensu stricto, a savanna physiognomy highly diverse in terms of herbaceous and woody species (Ribeiro & Walter 1998) and gallery forests, which form narrow strips of arboreal vegetation along river basins and contain approximately one third of the tree species that are found within the Cerrado biome (Felfili 1995, Ribeiro & Walter, 2001)
Cerrado sensu stricto and gallery forests are subjected to drastically different environmental pressures that impose strong constraints on species distributions in these two types of physiognomies
Summary
The central part of Brazil is covered by a complex mosaic of grasslands, savanna and forests, known locally as the Cerrado, which originally covered an area of over 2 million km. The most prominent vegetation types are the cerrado sensu stricto, a savanna physiognomy highly diverse in terms of herbaceous and woody species (Ribeiro & Walter 1998) and gallery forests, which form narrow strips of arboreal vegetation along river basins and contain approximately one third of the tree species that are found within the Cerrado biome (Felfili 1995, Ribeiro & Walter, 2001). Cerrado sensu stricto and gallery forests are subjected to drastically different environmental pressures that impose strong constraints on species distributions in these two types of physiognomies. The species of savanna and forest should behave as distinct functional groups due to different selective pressures imposed by these environments (Hoffmann et al 2005)
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