Leaf anatomical changes in Populus trichocarpa, Quercus rubra, Pseudotsuga menziesii and Pinus ponderosa exposed to enhanced ultraviolet-B radiation

agotamiento del ozono biomasa biomass biomasse coniferales feuille fotoperiodismo gene genes hojas leaf area leaves ozone depletion photoperiodicity pinus ponderosa plant anatomy plant tissues plantule populus trichocarpa pseudotsuga menziesii quercus rubra rayonnement ultraviolet seedlings superficie foliar surface foliaire tejidos vegetales ultraviolet radiation