This research was supported by Fundo Europeu de Desenvolvimento Regional (FEDER) through Programa Operacional Fatores de Competitividade (COMPETE), and by National Funds through the Portuguese Foundation for Science and Technology (FCT) within the Project PTDC/AGR-CFL/112996/2009. FCT/MEC, through national funds, and co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020 provide financial support to Centre for Environmental and Marine Studies (CESAM – UID/AMB/50017). FCT also supported the fellowships of Barbara Correia (SFRH/BD/86448/2012) and Glória Pinto (SFRH/BPD/101669/2014). The James Hutton Institute receives support from by the Rural and Environment Science and Analytical Services Division of the Scottish Government. We thank Altri florestal for providing the plant material, and Lucinda Neves and Marta Pintó-Marijuan for technical support.