PENDLETON, ROSEMARY L.1*, BURTON K. PENDLETON, AND STEVEN D. WARREN2. 1USDA FS, Rocky Mountain Research Station, Shrub Sciences Laboratory, Provo, UT 84606, and, 2U.S. Army Construction Engineering Laboratory, Champaign, IL 61826. - Response of blackbrush (Coleogyne ramosissima) seedlings to inoculation with arbuscular mycorrhizal fungi.
Blackbrush, Coleogyne ramosissima, occurs as a landscape dominant in
the ecotonal region between hot and cold deserts of the western United
States. Revegetation efforts using blackbrush have met with limited
success, prompting speculation on possible interactions with soil
microorganisms, including mycorrhizal fungi. Form 1993 to 1997, we
conducted a series of experiments designed to test the effect of
inoculation with arbuscular mycorrhizal fungi on the growth of young
blackbrush seedlings under a variety of soil nutient conditions. In
all cases, growth of blackbrush sedlings was enhanced in the presence
of mycorrhizal fungi. Inoculation resulted in increased plant
biomass, decreased allocation to root systems in general and to fine
roots in particular, and increased tissue concentrations of both
phosphorus and nitrogen. Beneficial effects were most pronounced
under low nutrient conditions typical of blackbrush areas. The
addition of mycorrhizal fungi also significantly decreased the ability
of cheatgrass, Bromus tectorum, to compete with blackbrush seedlings
when grown at low soil nutrient levels. Revegetation of blackbrush
areas would likely benefit from the presence of mycorrhizal inoculum.
Soil fertilization, however, is detrimental to the establishment of
this species and is not recommended.
Key words: arbuscular mycorrhiza fungi, Coleogyne ramosissima, competition, revegetation, Rosaceae