Sensitivity of 20 provenances of pine and Sacred fir to photochemical oxidants

Abstract

The Desierto de los Leones National Park is located in the central region of the Mexican Republic, and belongs to the mountain system known as the Transverse Neovolcanic Axis; it has a total area of 1 523.95 hectares, and it is located to the south of the Mexico City atmospheric basin in the Distrito Federal. Eight Sacred fir (Abies religiosa) and 12 pine tree (Pinus hartwegii) provenances were planted inside the National Park, at three different altitudes. All the provenances were planted individually and with 3 randomized replications, in each and every one of the sites corresponding sites to each altitude (3 120, 3 245 and 3 370 m). Miller’s scale was used to assess their sensitivity to photochemical oxidants. In the first field assessment, the pine tree and Sacred fir provenances did not show any kind of ozone-induced foliar symptoms; nevertheless, after two consecutive years of assessment, most of them showed some of the characteristic ozone-induced symptoms (chlorotic mottling and banding), as well as premature defoliation. The index of leaf damage of the 20 provenances after two assessment years shows that the atmospheric ozone affected the foliage coloration and retention of all the provenances of P. hartwegii and A. religiosa, regardless of the plantation site of each species, as well as between and within the three different altitudes.