Water and nutrient status of oaks and their relationship with canopy defoliation

Abstract: The Andalusian Network on Forest Ecosystem Health (SEDA network) evaluates each year the status of forest health in more than 400 permanent plots. The water status is one of the most important indicators of oaks health. Water Content (WC) and Relative Water Content (RWC) are the most common indices used to evaluate the water status of tree leaves. The aim of this work was to assess the relationship between water and nutrient status of tree and canopy defoliation. WC, RWC and macronutrient concentrations of leaves were assessed through spectral indices. RWC varies positively related with K concentration of leaf. WC was negatively related with N concentration and positively with K and P concentrations. Tree canopy defoliation increased with increasing RWC and decreased when trees showed high N leaf concentration. Mean water status of tree within a plot was mainly determined by site factors and weather factors. The results suggest the knowledge of the water and nutrient status of tree will allow a better understanding and interpretation of the canopy defoliation and their relationship with changes in environmental conditions and management practices.