Rain exclusion effects on rock field species in phenology and ecophysiology performance: an isotopic approach

Abstract

Drought events have been increasing in the last years and the tropical and mountain regions are pointed as the most fragile regions to climate change. However, there is a lack of understanding on how species response to extreme droughts. We have manipulated the water availability in an area of rock outcrops field (campos rupestres), a biodiversity hotspot in Brazilian Cerrado Domain. To get a deeper understanding of how plants respond to drier climates, we need methods that integrate long-term ecophysiological responses such as the analysis of the isotopic composition of oxygen (´18Ocel) and carbon (´13Ccel) of the leaves cellulose. These analyses integrates carbon balance and water balance presented by the species. The aim of this project is to evaluate the functional responses of species subjected to drought in rock outcrop field using an isotopic approach (´18Ocel and ´13Ccel). The study was carried out in a rock-outcrop field at the "Serra da Canastra National Park" during 22 months with six abundant species in the area. We set eight rainfall exclusion plots (4x4m) and four control plots. The ecological performance of plants under contrasting water availabilities will be evaluated by the ´18Ocel and ´13Ccel analyzes of the leaves cellulose. These data will be essential to understand changes in the photosynthetic capacity and stomatal conductance of species growing in both natural and experimental conditions. It will make it possible to infer the processes that cause decline in these attributes and their relation to water availability in the environment. (AU)