Morphological and physiological responses of three plant species occurring in distinct altitudes in the Neotropical savannah

Abstract

Rupestrian fields are located above 900 m of altitude and have many endangered plants. They may present patches of Campo sujo (shrub savannah), which is a phytophysiognomy commonly found in Neotropical savannah at lower altitudes. Based on the atypical occurrence of the Campo sujo area were studied the morphological and physiological responses of three plant species in two altitudinal levels. Morphology parameters, stomatal conductance, and water potential were evaluated in leaves at rainy season. Environmental conditions and physiology were taken along specific days. High-altitude area presented lower temperatures and higher air relative humidity during the day than low-altitude area. Distinct and uneven responses in the production of stomata and the caliber of the sieve and tracheal elements among plants in the two areas were observed. Stomatal conductance was normally lower than high altitude. Water potential at high altitude was lower at predawn, similar at noon, and higher at the end of the daylight. We observed different strategies among the three species, without clear anatomy pattern. The lower stomatal conductance rates at high altitude that do not follow the pattern expected for the humidity levels are found, which may be the result of strong and frequent winds and low temperature. Water potential recovery may reflect higher air humidity observed on this site.