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A depiction of the layout of a vegetation manipulation study Manipulation Treatments

The remarkable success of cheatgrass is attributed to its prolific seed production and high competitive ability. In response, IFAFS scientists are looking for strategies to:

  • reduce the abundance of cheatgrass seeds
  • establish species that are competitive with cheatgrass

While it may seem counterintuitive given the cheatgrass/fire relationship, scientists think fire may aide restoration…if used just right.

This treatment is designed to reduce weed seed production and deplete available soil nitrogen. The first step is to seed with a fast-growing sterile hybrid crop. This has two purposes. First, this hybrid crop will take up soil nitrogen leaving less for cheatgrass. Rangeland fire crew starting a prescribed burn Second, the fast-growing crop will dry early to carry a prescribed fire before cheatgrass seeds fall to the ground. The sterile hybrid plants don't produce viable seeds. The next step is to conduct a prescribed burn. The idea is to destroy the cheatgrass seeds as well as volatilize nitrogen into the atmosphere. The final step is planting the species found to be most competitive with cheatgrass in the ‘Competition Comparison ’ study described in this website.

IFAFS personel doing a rangeland planting

Another treatment involves herbicide application to control cheatgrass, followed by a seeding of the most competitive species from the ‘Competition Comparison ’ study. This treatment is similar to seed-burn-seed yet no nitrogen is volatilized through fire.

Control Treatments
A control treatment provides a baseline for comparison of other treatments. For example, if you apply a treatment in an exceptionally dry year, cheatgrass may grow poorly just from drought and not due to the treatment. IFAFS range technician counting plant densityControl treatments may not be ‘treated’ with anything, yet are vital for key insights into what ‘really’ happened. Two control treatments are used in the IFAFS manipulation experiments. One was simply a random selection of cheatgrass plots without any added treatment. The other involved planting the same competitive species from the ‘Competition Comparison ’ study, without any method of cheatgrass regulation.

IFAFS study biomass measurement
To collect data from this experiment, scientists will examine the seedbank to see if cheatgrass is being depleted in any treatments. They will also monitor survival of the desirable species and cheatgrass density.

-Plot layout: IFAFS photo.
-Prescribed burn: Jacob Landmesser.
-Range planting: Loren St.John.
-Cheatgrass density evaluation: Scott Shaff.
-Biomass measurement: IFAFS photo.