Juniper (Juniperus spp.) encroachment into sagebrush (Artemisia spp.)-bunchgrass communities has reduced understory cover on millions of hectares of semiarid rangelands. Mechanical masticators shred trees to restore desirable vegetation and reduce the potential for catastrophic wildfire. Mechanical mastication where juniper density is high and perennial grass cover is low brings a risk of invasive weed dominance unless perennial species are established. To determine whether juniper mastication favors annual- or perennial-grass establishment, we compared seedling emergence, tillers, and aboveground biomass of cheatgrass (Bromus tectorum L.) and Anatone bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Löve). Comparisons were made among hand-planted rows between and under juniper canopies of masticated and adjacent untreated control areas at three locations in Utah. Bluebunch wheatgrass had 16% (95% CI: 11-21) and cheatgrass had 10% (95% CI: 5-15) fewer seedlings emerge per row in masticated than untreated areas (P<0.001). However, bluebunch wheatgrass had 3.2 (95% CI: 2.0-5.2) times more tillers and 1.9 (95% CI: 1.6-2.2) times more aboveground biomass per row in masticated than untreated areas (P<0.001). Similarly, cheatgrass had 2.3 (95% CI: 1.5-3.8) times more tillers, 2.0 (95% CI: 1.7-2.4) times more aboveground biomass, and 11.4 (95% CI: 6.3-20.7) times more spikelets per row in masticated than untreated areas (P<0.001). This increased seedling growth in masticated areas was associated with increased inorganic nitrogen and soil water compared to untreated areas. Because mastication improves the growth of both cheatgrass and bluebunch wheatgrass seedlings, it could support dominance by either annual- or perennial-life forms. To avoid cheatgrass dominance where perennial understory cover is limited and cheatgrass propagule pressure is high, mastication should be accompanied by seeding desirable perennial species such as Anatone bluebunch wheatgrass. The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information. Migrated from OJS platform August 2020
Scholarly peer-reviewed articles published by the Society for Range Management. Access articles on a rolling-window basis from vol. 1, 1948 up to 5 years from the current year. Formerly Journal of Range Management (JRM). More recent content is available by subscription from SRM.