Observations of ozone-induced foliar injury on black cherry (Prunus serotina, var. capuli) within the Desierto de Los Leones National Park, Mexico City

agentes nocivos air pollution altitud altitude arbre forestier avejentamiento color colour couleur damage facteur nuisible feuille foliage forest trees hojas injurious factors leaves mexico mexique ozone ozono prunus serotina senescence symptome symptoms urban areas zonas urbanas zone urbaine