Probability of mortality by fire damage of young Pinus hartwegii Lindl. trees in the Izta-Popo National Park - Robles-Gutiérrez, César A.; Velázquez-Martínez, Alejandro; Rodríguez-Trejo, Dante A.; Reyes-Hernández, Valentín J.; Etchevers-Barra, Jorge D.