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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Publications at this Location » Publication #197728
Title: REVEGETATING RUSSIAN KNAPWEED (ACROPTILON REPENS) INFESTATIONS USING MORPHOLOGICALLY DIVERSE SPECIES AND SEEDBED PREPARATION

Author
item Mangold, Jane
item Poulsen, Clare
item CARPINELLI, MICHAEL - GRANTS SOIL SURVEY OFFICE

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2007
Publication Date: 7/1/2007
Citation: Mangold, J.M., Poulsen, C.L., Carpinelli, M.F. 2007. Revegetating Russian knapweed (Acroptilon repens) infestations using morphologically diverse species and seedbed preparation. Rangeland Ecology and Management 60(4):378-385.

Interpretive Summary: Because highly degraded pastures and rangeland dominated by Russian knapweed are often devoid of desirable plants, establishing desirable, competitive plants is essential for enduring management of Russian knapweed-infested rangeland and pastures. At two sites in southeastern Oregon, we sprayed Russian knapweed with glyphosate; prepared a seedbed by burning, tilling, or leaving untreated; and seeded with alfalfa, Siberian wheatgrass, pubescent wheatgrass, or a combination of the three. Seeding alfalfa decreased reinvasion of Russia knapweed by about 50-60% at one site, but otherwise, seeding treatment had little influence on seeded species density or Russian knapweed density. Tilling generally reduced Russian knapweed density and resulted in the best establishment of seeded species. Variability in annual precipitation appeared to influence seeded species establishment. This study suggests shallow tilling followed by drill seeding desirable forbs and grasses may provide the best results for those revegetating Russian knapweed-infested pastures and rangeland.

Technical Abstract: Highly degraded pastures and rangeland dominated by Russian knapweed (Acroptilon repens [L.] DC) are often devoid of desirable plants. Control efforts may be ephemeral because propagules of desirable species are not available to reoccupy niches made available by control procedures. Establishing desirable, competitive plants is essential for enduring management and restoration of Russian knapweed and other weed-infested plant communities. The objective of this study was to investigate the effectiveness of revegetating Russian knapweed-infested pastures with 3 nonnative, morphologically diverse species following 1 of 3 seedbed preparation treatments. In successive years at 2 similar sites in southeastern Oregon, we sprayed Russian knapweed with glyphosate, then prepared the seedbed by burning, tilling, or leaving untreated. Following seedbed preparation, we seeded a perennial forb (alfalfa [Medicago sativa L.]), a bunchgrass (Siberian wheatgrass [Agropyron fragile {Roth} P. Candargy ssp. sibericum {Willd.} Melderis]), and a sod-forming grass (pubescent wheatgrass [Elytrigia intermedia {Host} Nevski ssp. trichophora {Link} Tvzel]) in monocultures and 2- and 3-species mixtures. We measured Russian knapweed and seeded species density 1 and 2 years following seeding. The forb seeding treatment decreased reinvasion of Russia knapweed by about 50-60% at 1 site, but otherwise, seeding treatment had little influence on total seeded species density or Russian knapweed density. Tilling generally resulted in a 35-40% reduction in Russian knapweed density compared to the control and resulted in the highest establishment of seeded species. Variability in annual precipitation appeared to influence seeded species establishment between the sites. Our results suggest shallow tilling (10-15 cm) followed by drill seeding desirable forbs and grasses may provide the best results when revegetating Russian knapweed infestations. Follow-up management should include strategies to enhance desirable species production while minimizing Russian knapweed reinvasion.