The value of mountain rye (Secale montanum Guss.) for competitive suppression of 2 annual bromegrasses (downy brome, Bromus tectorum L. and Japanese brome, B. japonicus Thunb) was investigated in a 3-year study on reclaimed coal mined lands in southeastern Montana. Rye established rapidly and vigorously, but did not persist appreciably (either through initially established plants or new seedlings) after the second year. However, mountain rye significantly reduced growth and reproduction of annual bromes during the first 2 growing seasons. Mountain rye also inhibited growth of other concurrently seeded perennial grasses during the first 2 seasons. Annual brome soil seedbanks were not sufficiently reduced in rye-seeded plots to prevent an eventual, third year recovery of brome productivity after a massive dieback of rye between the second and third growing seasons. Mountain rye therefore proved effective for short but not for longer-term control of annual bromes. This study did not allow distinction between the known short-lived nature of mountain rye and/or local environment as causal factors for the massive dieback after the second year.

Graminoid standing crop in June 1985 on areas infested with white grubs (Phyllophaga anxia Leconte) (average density = 47 grubs m-2) was 92% less than on uninfested rangeland (average density < 2 grubs m-2). Study area was the Central Grasslands Research Center in south-central North Dakota. Infestations were noticeably associated with communities dominated by western snowberry (Symphoricarpos occidentalis Hook.) with an understory subdominance of Kentucky bluegrass (Poa pratensis L.). The objective of our study was to assess the initial impact and subsequent recovery of infestation on community standing crops and plant densities. Mid and late summer standing crops of Kentucky bluegrass and other grasses were significantly less (P < 0.05) on infested than uninfested sites between 1985 and 1987. Graminoid density was less (P < 0.05) on infested than uninfested sites during 1985 and 1986. Post-infested standing crop and density of forbs increased (P < 0.05) on infested sites. Infestation of sites subsequently provided habitat for establishment of noxious weeds such as wormwood sage (Artemisia absinthium L.). Management techniques to enhance the recovery of grasses and eliminate establishment of noxious weeds may be necessary.

Black-and-white photographs were used to estimate seasonal trends in whole plant leaf area of honey mesquite (Prosopis glandulosa var. glandulosa Torr.) trees occurring on a site with limited subsurface water. Height and canopy width of the trees ranged from 1 to 5 m and 1 to 7 m, respectively. Images consisted of profile-view angles of trees occurring on flat terrain. Four image variables, height, width, canopy profile perimeter length, and canopy profile area were obtained from the photographs and used to predict leaf area of unharvested trees. Predictive equations were based on adjacent trees which were photographed and harvested for actual leaf area determination. Canopy profile area was evaluated as the most accurate image variable for predicting leaf area. Whole plant leaf area of unharvested trees varied within and between growing seasons and was dependent on precipitation patterns. During the 1987 growing season, leaf area declined significantly by 14.6% from 17.1 m2 (1 leaf surface) in May to 14.6 m2 in August, in conjunction with a mid-summer dry period. Leaf area increased in September 1987 in response to late-summer precipitation. Leaf area was less in the spring of 1988 than the spring of 1987 because of lower precipitation during the winter prior to the 1988 than the 1987 growing season. Leaf area did not decline significantly from spring to mid-summer in 1988 as it did the previous year because of atypically high precipitation in July 1988. Leaf area did not increase in September of 1988 as it did in 1987 because of lack of late-season rains in 1988. These results suggest mesquite on this study site used partial leaf shedding to augment drought resistance.

Accumulation of wolf plants in rangeland pastures frequently results in waste or incomplete utilization of high quality forage by cattle. The objective of this research was to establish the degree of sensitivity of cattle to cured stems in crested wheatgrass (Agropyron desertorum (Fischer ex Link) Schultes) at 3 stages of phenology (late-boot, anthesis, and quiescence). This was accomplished by providing individual plants having densities of 0, 3, 6, 9, or 12 cured stems per dm2 basal area and measuring frequency and degree of utilization after exposure to cattle grazing. Project design was a split-plot in a randomized complete block with 3 replications, 3 stages of phenology as whole plots, and 5 densities of stems as treatments. A significant (P<0.01) phenology X treatment interaction occurred with cattle being equally sensitive to all treat- ments containing stems at late-boot and anthesis and oblivious to their presence at quiescence. At late-boot and anthesis stages of phenology 75% of plants with no stems were grazed while only 45% of plants with stems were grazed. Respective levels of utilization from the same treatments were 25 and 8%. A negative response was exhibited by cattle during anthesis when as little as 4% of biomass was contributed by cured stems. These results suggest that old growth stems should be removed or their presence noted as a covariate when conducting palatability studies or when observing plant-specific responses to defoliation by cattle. Cattle were not sensitive to treatments at quiescence when roughly 75% of plants in all treatments were defoliated with 25% herbage removal. This suggests that heavy grazing of a pasture with an objective of obtaining utilization of wolf plants would be most successful after all forage has cured, and cattle are less selective.

A 3-year field study was conducted near Grassrange, Montana. (Latitude 46 degrees 50'N and Longitude 108 degrees 50'W) to determine the effect of leafy spurge (Euphorbia esula L.) shoot density, control, and canopy cover on the utilization of forage by cattle. Picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) was applied at 0.28 to 2.24 kg ae/ha on leafy spurge-infested native pasture to establish different levels of leafy spurge shoot density and canopy cover. Utilization of forage was influenced by leafy spurge shoot density (r = -0.65) and canopy cover (r = 0.87) and was not related to the amount of forage (r = -0.1) produced. A leafy spurge canopy cover of 10% or more and a leafy spurge shoot control value of 90% or less resulted in a significant decrease in utilization of forage by cattle.

We censused breeding nongame birds on replicated 5- and 6-year post herbicide-treated (tebuthiuron and triclopyr) and untreated cross timbers rangeland in central Oklahoma. Twenty species of breeding birds were observed. No treatment effects were detected for total bird density, species diversity, or richness; however, species composition varied considerably among treatments. Control sites supported species associated with closed canopy woodlands, and treated sites supported species associated with brushy and prairie habitat. Generally, control sites had greater foliar cover, fewer snags, and less slash and herbaceous cover than treated sites. Densities of 6 of the 7 most abundant bird species were correlated variously with habitat variables. We concluded that changes in habitat structure resulted in differences in bird species composition among treatments.

Bur buttercup (Ranunculus testiculatus Crantz) is an alien annual species that has spread rapidly through range and croplands in the western United States. This species is potentially poisonous and is currently a weed in cereal grain fields. We investigated the germination of the achenes (seeds). About 30% of the seeds of bur buttercup germinated without pretreatment, but only at cool to cold temperatures (maximum germination 28% at 5 degrees C). Germination was not enhanced by light, washing, or prechilling of seeds. Acid scarification for 25 minutes increased germination. Enrichment of the germination substrate with 0.289 mmol L-1 gibberellic acid (GA3) and 0.01 mol L-1 potassium nitrate (KNO3) synergistically enhanced the germination of acid scarified seeds. Incubation of seeds pretreated in this manner at 55 constant or alternating temperatures resulted in maximum germination of 70%. All temperature regimes with optimum germination (defined as not lower than the maximum observed and one-half its confidence interval at 0.01 level of probability) occurred at relatively cool temperatures. Temperatures above 30 degrees C greatly suppressed or inhibited germination. Embryonic plants dissected from the achene costs had 60% germination without additional pretreatment, but only at cool to cold incubation temperatures. The germination-dormancy requirements of bur buttercup seeds are obviously complex, but about 30% of the seeds appear adapted for germination at cold seedbed temperatures, which fits with the extreme ephemeral growth habit of the species.

Two simulated pasture studies were carried out at Swift Current, Sask., to determine the effects of date and height of first harvest in the year following establishment on the yield of 4 species in subsequent years. Altai wild ryegrass [Leymus angustus (Trin.) Pilger], Russian wild ryegrass [Psathyrostachys junceus (Fisch.) Nevski] and crested wheatgrass [Agropyron desertorum (Fisch.) Schult.] were used in both studies; alfalfa [Medicago sativa L. ssp. X varia (Martyn) Arcangelil] was included in the second study only. In both studies plots were first cut at 1 of 6 dates, approximately 2 weeks apart, during the period from mid-May to late July in the year following establishment. Cuts were made either at a 5 cm or at a 10 cm height to simulate medium grazing and light grazing, respectively. After the first cut, forage was harvested in that year whenever 10 cm of regrowth was present. In the next 5 years in the first study and 3 years in the second, all forage was harvested at 5 cm height on 15 May and thereafter whenever 10 cm of regrowth was present. Treatment effects were greatest in the year treatments were imposed and in the first post-treatment year. In the treatment year, highest forage yields were obtained from plots cut at 5 cm, but in subsequent years, forage yields were higher from plots cut at 10 cm in the treatment year. Moisture conditions in the seeding and establishment years affected the response to treatments. Date of first cut in the treatment year affected yields in subsequent years in both experiments although differences declined with time. Crested wheatgrass was more affected by date of first cut than were the other species. The cutting dates for highest yields in each case correlated with flowering date and indicate that seedings of these grasses should not be harvested until they have flowered. The results of this study also indicate that to ensure continued high forage yields, the first harvest of these grasses should be less intense than subsequent harvests.

Effects of prescribed fire and roller chopping applied in 2 seasons on woody vegetation and the associated avian community of a southwestern Florida former dry prairie were studied. There were 5 vegetation treatments with 2 replications of each; treatments were control, winter burn, winter chop, summer burn, and summer chop. Percent shrub cover was sampled with line intercept transects. Birds were censused 25 times using the variable circular plot method. Burning in either season reduced shrub cover temporarily; chopping in either season reduced shrub cover significantly and it remained reduced throughout the 15 months of this study. Bird species richness and abundance were similar in control and burn plots. Birds were not seen in summer chop plots up to 5 months posttreatment. Bird species richness and abundance remained low in both winter and summer chop plots. Bird species that were observed in chop plots were mostly open country, grassland inhabitants, indicating a trend toward prairie restoration.