TITLE:
Competition of Squirreltail with Cheatgrass at Three Nitrogen Levels
AUTHORS:
Allan R. Stevens, Val Jo Anderson, Rachel Fugal
KEYWORDS:
Accession; Biomass; Bromus tectorum; Elymus elymoides; Seedling
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.7,
March
26,
2014
ABSTRACT: Squirreltail (Elymus elymoides [Raf]
Swezey) can grow in cheatgrass (Bromus tectorum L.) stands, and has reduced
the biomass production of cheatgrass in its immediate vicinity. A field experiment
was conducted to determine: 1) if competition for nitrogen resources occurs
between seedlings of squirreltail and seedlings of cheatgrass, under low,
medium, and high nitrogen levels, and; 2) if competition for nitrogen resources
in the seedling stage is a mechanism that allows squirreltail to establish in
cheatgrass stands. Five accessions of squirreltail were each seeded with a
single accession of cheatgrass in a cultivated field near Ephraim, Utah in the
fall of 1995 and again in 1996. A completely randomized strip-plot design with
3 replications was used including the 5 joint seedings as well as pure seedings
of each accession of both species. Three nitrogen levels representing high,
medium (control), and low were applied. The study was replicated over 2 years
in different areas of the same field. Harvests of above-ground biomass of
squirreltail and cheatgrass within each treatment were conducted in July of
1996 and 1997. Using biomass production as a measure of efficient nitrogen use,
cheatgrass competed for and used nitrogen resources more efficiently than
squirreltail when nitrogen was not limiting. All squirreltail accessions were
able to compete for and use nitrogen more efficiently than cheatgrass when
there was low availability of nitrogen. Some accessions of squirreltail
competed for nitrogen resources more efficiently than others both in the
control and at the reduced nitrogen level. White Rocks and Sublette
squirreltail accessions were the best competitors with cheatgrass at the low
nitrogen level reducing the cheatgrasss biomass by as much as 75% and 67%
respectively. An intermediate competitor with cheatgrass was the Gunnison
accession. The Washakie and Pueblo accessions were poor competitors with
cheatgrass at low nitrogen levels.