Functional trait differences between native bunchgrasses and the invasive grass Bromus tectorum

Abstract

We conducted 30-and 60-d greenhouse experiments to compare functional traits of Bromus tectorum (invasive annual grass) and four perennial bunchgrasses under well-watered or drought conditions. Even under drought, B. tectorum experienced significantly less stress (i.e., higher xylem pressure potential and greater shoot water content, water use per day and water-use efficiency) and biomass production than the perennial grasses after 30 d. However, after 60 d, its superiority was reduced under infrequent watering. Differences among perennial grasses were more pronounced for physiological traits under infrequent watering and for morphological traits under frequent watering. Elymus multisetus (fastgrowing species) had a higher transpiration rate, lower leaf temperature, and lower water-use efficiency than the other grasses after 30 d. In contrast, Pseudoroegneria spicata (slow-growing) had lower xylem pressure potential and higher leaf temperature than all other grasses under infrequent watering. Under frequent watering, shoot dry mass and specific leaf area of B. tectorum was matched by Elymus wawawaiensis (moderate-growing species). Our results indicate that multiple-species plantings or seedings are necessary to foster greater weed resistance against B. tectorum. We also emphasize that when choosing plant material for restoration, performance during both pulse (resource-rich) and inter-pulse (resource-poor) periods should be considered.

Using Genomic Selection to Develop Performance-Based Restoration Plant Materials

“…The higher root surface area of downy brome seedlings may account for their greater vigor relative to those of BBWG [ 74 ]. Compared to BBWG, downy brome seedlings are better able to avoid stress when infrequently watered, as evidenced by a less-negative xylem pressure potential, higher shoot water content, lower leaf temperature, and lower stomatal conductance [ 90 ]. Crested wheatgrass seedlings increased both shoot and root dry-matter in response to increased water availability, thereby maintaining high root mass fraction (root mass/[shoot + root mass]) [ 68 ].…”