Is squirreltail growing with cheatgrass a better competitor than squirreltail growing without cheatgrass

Background/Question/Methods:

The perennial bunchgrass squirreltail (Elymus elymoides) is one of the few native species that can coexist with cheatgrass (Bromus tectorum), an exotic annual grass, in the Intermountain West.  This study examined seedling characteristics of squirreltail growing in cheatgrass invaded areas versus un-invaded areas dominated by big sagebrush (Artemisia tridentata) and other native bunchgrasses.  Have squirreltail populations that coexist with cheatgrass developed morphological differences that might become advantageous for surviving with cheatgrass?  Populations of squirreltail that have developed traits to compete with cheatgrass would be a valuable resource for restoration and rehabilitation efforts throughout the Intermountain West.

At three sites (one each near Boise, ID, Wells, NV, and Kelton, UT), seeds were collected from 8 mother plants in a cheatgrass invaded area and eight mother plants from an adjacent un-invaded area.  Seeds were cleaned, weighed and sown in slanted root viewing growth boxes in a greenhouse for 34 days to determine seedling growth characteristics.  Germination and emergence dates were recorded in the beginning of the study. Thereafter, daily measurements were taken on leaf height, number of leaves, and root growth. 

Results/Conclusions:

Preliminary results show that site effects were significant for nearly all variables measured including seed weight, root and shoot biomass, emergence date, leaf length, leaf and root growth rates, and total root length.  Invasion status was marginally significant (p = 0.0702) for emergence date, with the seedlings from the un-invaded locations emerging 1 day earlier than seedlings from invaded locations.  Site by invasion status was also significant for time until the appearance of the 4th leaf, root biomass, secondary root length, total root length, and root growth rate.  For example, for root growth rate, root biomass, and root length there were no significant differences between the seedlings from invaded and un-invaded locations at the Idaho and Utah sites.  In contrast, seedlings from the un-invaded location at the Nevada site had twice as much mass (0.008g vs. 0.004g), grew nearly twice as fast (1.91cm/day vs. 1.10cm/day), and nearly twice the length (27.87in vs. 15.99in) as the seedlings from the invaded location.  These preliminary results suggest that at some sites there are morphological differences between squirreltail populations growing in invaded sites versus un-invaded sites.  However, more research expanding the number of plants and sites is required to better tease out these differences.