1 23 Trees Structure and Function ISSN 0931-1890 Trees DOI 10.1007/s00468-013-0869-x Ecological behavior of Quercus suber and Quercus ilex inferred by topographic wetness index (TWI) Andrea Petroselli, Federico Vessella, Lucia Cavagnuolo, Gianluca Piovesan & Bartolomeo Schirone