INFLUENCE OF JAPANESE BROME ON WESTERN WHEATGRASS YIELD

Japanese brome (Bromus japonicus Thunb.) has invaded many northern mix ed-prairie plant communities, Understanding interactions of population dynamics of this and associated species is critical for proper manage ment of communities infested with this annual, Objectives of this stud y were to determine the effect of Japanese brome removal on abovegroun d forage production and daily plant water relations of western wheatgr ass [Pascopyrum smithii Rydb, (Love)] and Japanese brome in a western wheatgrass dominated northern mixed grass prairie community, During ea rly spring of 1991, a wet year, and 1992, a dry year, 2 treatments, un disturbed and complete (total) removal of Japanese brome seedlings, we re applied by hand at silty clay loam and clay field sites in circular , l-mz quadrats, Vegetation in additional quadrats was left undisturbe d or Japanese brome was removed to assess plant water relations at eac h site in 1992, Total standing crop was reduced 500 kg ha(-1) with rem oval of Japanese brome, while standing crop of western wheatgrass was increased 220 kg ha(-2) with Japanese brome removal, Increased standin g crop of western wheatgrass appeared to result from increased tiller density of 153 tillers m(-2) rather than increased weight per tiller. Western wheatgrass water relations were essentially unaffected by Japa nese brome removal in 1992, Removal of Japanese brome from Northern Gr eat Plains plant communities may increase production of associated per ennial grasses, but managers should also expect a short-term decrease in total standing crop.