Functional Strategies of Caatinga trees: a hydraulic approach

Abstract

The Caatinga is an ecosystem of the Brazilian semiarid that presents an expressive diversity of plants, whose species are adapted to severe droughts and adverse climatic conditions that occur seasonally in the region. It is one of the least studied and protected areas of Brazilian natural regions and has undergone an extensive process of exploitation and unsustainable use of natural resources. Furthermore, the region has a scarce and irregular precipitation regime associated with high potential evaporation. These factors influence several physiological processes in plants and increase complexity to the set of functional strategies selected to survive in these local hydro-edaphic conditions. My objective is to understand the hydraulic strategies of Caatinga tree species using functional traits data and to evaluate the species vulnerability to drought, to generate knowledge that improves the explanation of spatial distribution of species. I will develop this study at 3 forest areas located in the state of Pernambuco within the domains of the Caatinga biome. I will measure specific leaf area (SLA), stomatal conductivity, specific xylem conductivity, xylem vessel diameter and vessel density, wood density and leaf area:sapwood area ratio. I will determine the main trade-offs between the functional hydraulic traits of Caatinga tree species and will analyze inter and intra-specific variability in species belonging to the most abundant families in the region. Also, I will analyze the historical series of drought through the radial rings of growth in the stem and we will use statistical models to understand the spatial distribution of the species through the data of hydraulic functional traits. Thus, I will be able to increase the knowledge about the functional strategies of the Caatinga species, contributing to future predictions of species distribution patterns in a climate change scenario.