Updated publication reference for PubMed record(s): 31907313. The use of hybrid-poplar tree plantations as a source for biofuels and biomass production in temperate regions of the Northern Hemisphere has also, unintentionally, increased forest isoprene emissions to the atmosphere. The consequences of increased isoprene emissions include higher rates of tropospheric ozone production and increases in atmospheric aerosol production. Using RNA interference (RNAi) to suppress isoprene emission in several gene insertion events of hybrid-poplars, we show that this trait, which has been assumed as a requisite for the tolerance of abiotic stress, is not required for high rates of woody biomass production, even in extremely hot and dry climates. Biomass production over four years in experimental poplar plantations in Arizona and Oregon was similar among genetic lines that emitted or did not emit significant amounts of isoprene. Lines that had substantially reduced isoprene emission rates also showed decreases in flavonol pigments, which reduce oxidative damage during extremes of abiotic stress; a pattern that would be expected to amplify metabolic dysfunction during abiotic stress. Compensatory increases in the expression of other proteomic components, however, such as those that disable superoxide and other free radicals, and the fact that most biomass is produced during the spring, prior to the hottest and driest part of the growing season, explains the apparent paradox of high biomass production with low isoprene emission. The results of this study provide optimism for designing agroforest plantations of the future that provide high rates of lignocellulose production while eliminating detrimental effects of isoprene emission on atmospheric quality.