Estimation of chlorophyll in Quercus leaves using a portable chlorophyll meter: effects of species and leaf ageFernando Silla, Ana González-Gil, Mª Esther González-Molina, Sonia Mediavilla and Alfonso EscuderoAnn. For. Sci., 67 1 (2010) 108DOI: https://doi.org/10.1051/forest/2009093