Journal Article Research Support, Non-U.S. Gov't 00BH33GNGH Cadmium N762921K75 Nitrogen Populus deltoides 1406-65-1 66H7ZZK23N Biological toxicity Chlorophyll Comparative Study Defense pathways Metals, Heavy Ozone Ozone resistance Pestalotiopsis microspora Sex-specificity Soil biogeography carbon and nitrogen stoichiometry dioecious plants ecological function elemental defense hypothesis fine roots heavy metals leaf pathogenic fungus microbial diversity plant functional groups plant–pathogen interactions