Ecophysiological performance of four species of Clusiaceae with different modes of photosynthesis in a mosaic of riverine, rupestrian grasslands, and cerrado vegetation in SE-Brazil

摘要

Key messageAmong four species of Clusiaceae (sensu lato) occurring in a mosaic of different types of tropical vegetation, Kielmeyera coriacea Mart. & Zucc. and Calophyllum brasiliense Camb. were C-3-species with similar performance at micro-sites of contrasting water supply, Clusia criuva Cambessalthough potentially a C-3/CAM intermediate speciesperformed C-3-photosynthesis, while Clusia arrudea Planchon & Triana ex Engl. performed C-3-photosynthesis or CAM-cycling depending on site characteristics and dry or wet season. Depending on individual species, C-3-photosynthesis proves to be a suitable option at a variety of environmental conditions, while CAM-cycling appears to be an escape under more severe stress.AbstractIn this ecophysiological field work, we investigated possible microhabitat-dependent expression of modes of photosynthesis among species of Clusiaceae (sensu lato) in a mosaic of tropical vegetation. The study site was in the Serra de SAo Jose (21 degrees 08'S, 44 degrees 17W; in the municipality of Tiradentes, state of Minas Gerais, SE-Brazil). The mosaic of tropical vegetation types was made up of rupestrian grasslands, cerrado, small rock outcrops, and riverine and gallery forest alongside a small river. Four species were measured, namely C. criuva Camb., C. arrudea Planchon & Triana ex Engl., K. coriacea Mart. & Zucc., and C. brasiliense Camb. K. coriacea and C. brasiliense performed C-3-photosynthesis with midday depressions and reversible acute photoinhibition in response to varying environmental conditions related to habitat types and wet and dry seasons, respectively. The C-3/CAM intermediate C. criuva also performed C-3-photosynthesis with midday depression and acute photoinhibition. It appeared not to be stressed enough to switch to its intrinsic CAM option. In contrast, while C. arrudea under favourable conditions in the gallery forest and the wet season also performed C-3-photosynthesis, under drier conditions, it used CAM-cycling. For particular species, realization of CAM-options is a possibility of acclimation. Other species contemporarily may rely on different alternatives such as plastic performance of C-3-photoynthesis. At the microsite level, overlapping functional diversity of species and diversity of habitats contributes to the complexity of this vegetation type.