The choice of plant materials is an important component of revegetation following disturbance. To determine the utility and effectiveness of various perennial grass species for revegetation on varied landscapes, a meta analysis was used to evaluate the stand establishment and persistence of 18 perennial cool-season grass species in 34 field studies in the Intermountain and Great Plains regions of the United States under monoculture conditions. Combined across the 34 studies, stand establishment values ranged from 79% to 43% and stand persistence values ranged from 70% to 0%. Intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D. R. Dewey), tall wheatgrass (Thinopyrum ponticum [Podp.] Z.-W. Liu & R.-C. Wang), crested wheatgrass (Agropyron spp.), Siberian wheatgrass (Agropyron fragile [Roth] P. Candargy), and meadow brome (Bromus riparius Rehmann) possessed the highest stand establishment (! 69%). There were no significant differences among the 12 species with the largest stand persistence values. Basin wildrye (Leymus cinereus (Scribn. & Merr.)Á. Löve), Altai wildrye (Leymus angustus [Trin.] Pilg.), slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners), squirreltail (Elymus spp.), and Indian ricegrass (Achnatherum hymenoides [Roem. & Schult.] Barkworth) possessed lower stand persistence ( 32%) than the majority of the other species, and Indian ricegrass (0%) possessed the lowest stand persistence of any of the species.Correlations between environmental conditions and stand establishment and persistence showed mean annual study precipitation to have the most consistent, although moderate effect (r¼~0.40) for establishment and persistence. This relationship was shown by the relatively poor stand establishment and persistence of most species at sites receiving less than 310 mm of annual precipitation. These results will be a tool for land managers to make decisions concerning the importance of stand establishment, stand persistence, and annual precipitation for revegetation projects on disturbed sites.

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The explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), a major component of munitions, is used extensively on military training ranges. As a result, widespread RDX pollution in groundwater and aquifers in the United States is now well documented. RDX is toxic, but its removal from training ranges is logistically challenging, lacking cost-effective and sustainable solutions. Previously, we have shown that thale cress (Arabidopsis thaliana) 2 engineered to express two genes, xplA and xplB, encoding RDX-degrading enzymes from the soil bacterium Rhodococcus rhodochrous 11Y can break down this xenobiotic in laboratory studies. Here, we report the results of a 3-year field trial of XplAB-expressing switchgrass (Panicum virgatum) conducted on three locations in a military site. Our data suggest that XplAB switchgrass has in situ efficacy, with potential utility for detoxifying RDX on live-fire training ranges, munitions dumps and minefields. Main textDuring World War II, RDX production peaked at 15,000 tons a month in the United States, and 7000 tons a month in Germany 1 . A major component in many munitions 1 , the demand for RDX is still high with a market size of $10.43 billion in 2018 2 . But RDX is toxic to soil organisms and humans, recalcitrant to degradation in the environment, and extremely mobile, readily moving into the groundwater [3][4][5][6][7] . These properties have resulted in the buildup of RDX in soil and groundwater to levels that have then threatened, or affected, human health, such as contamination of a sole source aquifer at Cape Cod 8 , and exposure of individuals to RDX in the Bickford Case in Utah 9 .Global RDX-contaminated areas are hard to map: historical explosives contamination is poorly recorded, and for reasons of security and political sensitivity, locations of current military sites are not openly documented. Extended Data Figure 1 maps global locations of explosives contamination, with examples of specifically RDX contamination additionally listed, and described in Supplementary Table 1. Supplementary Table 2 demonstrates the scale of RDX contamination in the United States. Contamination is not just limited to active military ranges, but includes decommissioned ranges, munitions dump sites and minefields; extensive RDX plumes emanate from manufacturing sites 8,9 .