Authors arerangescienrist USDA-ARS, Fort Keogh Livestockand Range Research Loboratory, Miles City, Mont. 59301; research animal scientist USDA-ARS, Forage and Livestock Research Laboratory, El Reno, Okla. 73036; range ecologist USDI-BLM, Oregon State University, Corvallis, Ore. 97331; range scientist and research leader, and range scientist (retired) USDA-ARS, Fort Keogh Livestock and Range Research Laboratory, Miles City, Mont. 59301. Abstract Impacts of 7 range treatments and climate on late spring herbage standing crops (SC) were measured in rangelands near Miles City, Mont., from 1983 to 1990. Treatments, established in 8 pastures at 2 sites, were: (1) untreated control + season long grazing (SL); (2) soil tillage (ST) + SL; (3) ST + drill seeding legumes (DS) + SL; (4) brush control (BC) + ST + DS + switchback grazing (utilizing 2 pastures); (5) BC + ST + DS + SL; (6) ST + nitrogen fertilization + SL; and (7) contour furrowing (CF) + aerial seeding legumes + SL. Data were analyzed using years as a repeated measure. Treatments increased (prO.05) total SC 320 kg/ha over controls, but did not affect species/species group composition. Treated pastures produced similar (p10.10) SC of 881 kg/ha. Total SC averaged 490 kg/ha more (p10.05) in 1983,1986,1987,1989, and 1990 than in 1984,1985, and 1988. Perennial cool-season grass SC was greatest in 1986 (651 kg/ha). Peak annual grass SC (337-506 kg/ha) occurred in 1983 and 1984, the 2 years following ST or CF, and 1989 and 1990, the 2 years following severe drought. Although regression analyses showed fall, winter, and spring precipitation and temperature were closely related to spring SC, less than 50% of the variation in SC was accounted for when precipitation and temperature were summed on a l-month, 2-month, or 3-month basis. Above-average fall and spring precipitation (September and April) resulted in the greatest total SC. Species composition varied temporally with changing weather conditions and management strategies.

Prescribed burning was conducted in the fall and spring to evaluate the effects of fire on productivity of 3 forage species. Yield measurements were obtained throughout the growing season at biweekly intervals on western wheatgrass, blue grama, and tbreadleaf sedge. Supplementary measurements were made on vegetation cover and soil moisture. Herbage yield depended upon individual species, sampling date, and treatment. Spring burning of western wheatgrass and blue grama stimulated production by mid-and late-June, whereas fall burning also stimulated productivity but to a lesser degree. Production of threadleaf sedge was relatively unaffected by spring burning and reduced by fall burning. Fire can be used as a management practice to increase forage yield in the Northern Great Plains, but timing of utilization by livestock must receive careful consideration to assure maximum benefit. Fire has played an important historical role in the development of grassland communities (Daubenmire 1968; Komarek 1964, 1965). Nevertheless, negative attitudes toward burning have frequently limited application of fire as a management tool. Factors such as the threat of fire escaping the boundaries of a prescribed burn, temporary elimination of potentially usable forage, and the destructive effects of wildfires have all contributed to such attitudes. Only limited research has been conducted on the effects of burning on forage species in the Northern Great Plains. Lodge (1960) examined the effects of burning on crested wheatgrass (Agropyron desertorum), while Dix (1960) and Kirsch and Kruse (1972) reported on the effects of wildfire on mixed grass prairies in North Dakota. Prescribed burning has also been conducted in western wheatgrass (Agropyron smithii) communities in South Dakota (Gartner et al. 1978) and in the fescue grasslands of Canada (Bailey and Anderson 1978; Anderson and Bailey 1980). In general, these studies demonstrated that fire has management potential although additional research is needed to determine how individual species may respond (Bailey 1978). Our study was designed to evaluate the effects of prescribed burning on important forage species in the mixed grass prairie of eastern Montana. The primary objectives of the study were: (1) to examine post-burn herbage production of 3 species throughout the growing season, (2) to compare the effects of both fall and spring burning and (3) to determine if burning conditions could be simulated by a clipping treatment. Methods Three species were selected for investigation: western wheatgrass, blue grama (Bouteloua gracilis), and threadleaf sedge (Carex Authors are research plant physiologist and range scientist, respectively, USDA-ARS, Livestock and Range Research Station, Route I, Box 2021, Miles City, Montana 5930 I.

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Determining the percentage of ground covered by shrubby vegetation is an integral part of range inventory and of range condition and trend studies. Measurement of plant cover is used in making site descriptions and in studying brush control, seeding, and grazing management. A change in plant cover often reflects a change in management practices. No accurate method of measuring plant cover has been devised. In most instances only an estimation of plant cover is made. However, Smith (1944) showed that cover estimates vary significantly among individuals on different days and even on the same day. Many range technicians, land managers, and ecologists have recognized the need for a rapid, accurate, and easyto-use method of measuring plant cover. The loop procedure of the Parker 3-Step Method is used widely in condition and trend studies. Ash-inch loop is utilized to obtain the plant density index, a frequency measurement. Recently, Johnston (1957) employed the loop procedure to