This study was designed to provide information on cover, botanical composition, and frequency of major plant species in a brood-rearing area used by migratory geese south of Howe Island on the Sagavanirktok River Delta near Prudhoe Bay, Alaska. The area is split by the Endicott road and the information was also used to gain preliminary information concerning the effect of the road on goose and caribou activity. Transects on the east and west sides of the access road at the base of the Endicott causeway were established to evaluate occurrences of vegetation, goose fecal pellets, caribou tracks, and coastal debris. The point intercept method characterized plant cover, species frequency, and botanical composition. The recorded occurrence of fecal pellets and tracks on the transects were used as estimates of the presence of geese and caribou. Vegetative cover was 21% west and 38% east of the road near the Endicott causeway base in 1991. The 3 species most prominent west of the road were Carex sub-spathacea Wormsk., Salix spp., and Puccinellia phryganodes (Trin.) Scribn. & Merr. (botanical composition of 26, 23, and 21%, respectively). East of the road, Salix spp. (43%) dominated botanical composition followed by Carex aquatilis Wahlenb. (13%) and Dryas integrifolia M. Vahl (11%). The west and east sides differed botanically. Caribou tracks were observed in 60% of the transects on both sides of the road and goose fecal pellets were more prevalent on the west side (86%) than on the east side (48%). Geese pellets and caribou tracks occurred in different locations in the study area. Goose fecal pellets were from all goose species and may have included more than 1 year.

This study was conducted for 2 consecutive growing seasons in a temperate region of Pakistan to determine a residual phytomass level necessary to adequately protect the soil against accelerated interill erosion A rainfall simulator was used to apply rainfall to 48 (1 m square) circular plots arranged in a completely randomized experimental design, with 4 residual phytomass levels and 2 replications. The residual treatment with 3,024 kg ha-l phytomass resulted in the lowest erosion rates, and the treatment with 624 kg ha-l phytomass produced the highest erosion. Standing phytomass was the most important variable affecting erosion with foliar cover and basal cover also highly correlated to erosion.

The acquisition of water and regulation of its loss are important to plant 'success' in arid environments. Species existing over a range of environmental conditions should respond physiologically to varying conditions to maximize water use efficiency and avoid low tissue water potentials. Seasonal and diurnal ecophysiological responses of singleleaf pinyon (Pinus monophylla Torr. and Frem.) were investigated along an environmental gradient involving elevation, moisture and temperature in Nevada. The gradient was represented by study sites in black sagebrush (Artemisia nova A. Nels), mountain big sagebrush (Artemisia tridentata ssp. vaseyana Nutt.), and mountain mahogany (Cercocarpus ledifolius Nutt.) communities. Xylem pressure potential, conductance, and transpiration were measured over 2 growing seasons. Xylem pressure potential and leaf conductance ranged from -3.0 to -0.7 MPa and 0.01 to 0.43 cm s-l, respectively, during the study. Carbon isotope discrimination (delta) of needles was determined in August 1990. Differences in delta values were not significant between sites at the lowest and highest elevations but were significant between the driest site (black sage) and the relatively wetter site (mountain mahogany). Leaf conductance was influenced by but not strongly correlated with predawn xylem pressure potentials, relative humidity, and temperature. Generally, there was little difference in water use characteristics of singleleaf pinyon along the environmental gradient in this study. Thus, it appears that singleleaf pinyon's ability to exist over a range of environmental conditions is not a function of variable ecophysiological responses but an opportunistic response to the availability of resources and conditions suitabie for erowth to occur.

An observed increase in winterfat (Ceratoides lanata (Pursh) J.T. Howell) on ungrazed rangeland suggests that this shrub may potentially be an important forage resource in the Northern Mixed Prairie under improved grazing management. The objectives of this study were to: 1) compare density, frequency, and cover of winterfat in a grazed pasture and site that had been protected from grazing for about 30 years; and 2) evaluate regrowth of winterfat following defoliation during the growing season on a clayey range site in Saskatchewan. Density, frequency, canopy cover, and basal cover were significantly greater in the protected range than the grazed pasture. Density (1.1 SE +/- 0.01 plants m-2) and frequency (70% SE +/- 3.6) were about 2-fold greater, while canopy cover (7.0% SE +/- 1.4) and basal cover (1.7% SE +/- 1.5) were 7- to 8-fold greater, in the protected versus grazed range. When defoliated to a 5-cm stubble in May, June, or July plants produced significant amounts of regrowth but not when herbage was removed in August. When defoliated in late July or August current year production the following year was significantly lower than control and earlier defoliations. Current year production peaked in late July and August. Total standing crop was 2- to 4-fold greater in the control than the defoliation treatments because the biomass produced in previous years was removed from clipped plants. Because winterfat produces substantial amounts of new growth following defoliation in May, June, or July it is recommended that this shrub be grazed only once during the growing season to prevent grazing of this regrowth. Plants defoliated in May can potentially produce biomass equal to control the following year whereas plants defoliated in June, July, or August will likely require more than 1 year of rest to recover their annual productivity.

A 4-year study was conducted on Kansas Flint Hills bluestem range to monitor animal gain, grass, and forb standing biomass following grazing, plant population dynamics, and in 2 years, subsequent feedlot performance of steers under intensive-early stocking supplemented with increasing levels of sorghum grain. Each year from 1988 through 1991, crossbred beef steers were stocked at 0.24 ha/100 kg of initial steer weight from 5 May to 1; July. Steers in twice-replicated pastures were given no supplementation, 0.91 kg rolled sorghum grain per head daily, or 1.82 kg rolled sorghum grain per head daily, which corresponded to approximately 0, 0.3, and 0.6% of body weight-1. All steers were implanted with estradiol 17 beta in 1988 and zeranol in 1989-91 during initial processing and had unlimited access to a lasalocid/mineral mixture during the entire trial. In 1989 and 1990, representative groups of steers selected from all treatment/pasture combinations were subjected to a feedlot finishing phase and carcass data were obtained. Grass and forb standing crops were estimated each year at livestock removal in mid-July and again in early October. Pretreatment species composition and basal cover were determined in 1988 and compared to those at the end of the study. In mid-July, when cattle were removed, residual standing biomass of grass increased in direct proportion to increasing level of supplement. Standing biomass of grass at the end of the growing season did not differ among pastures with different supplement levels. Forb standing biomass did not differ among pastures with different supplement levels in July or October. Changes in plant populations among treatments during the course of the study were minimal. During the early portion of the grazing period, sorghum grain supplementation did not significantly influence steer gains, but average daily gain during the latter part of the grazing period increased in direct proportion to increasing level of sorghum grain supplement. Daily gain. feed intake, carcass characteristics, and gain:feed ratio were not different among treatments during the feedlot phase. Although conversion efficiencies may be economically marginal, low-level grain supplementation has the potential to increase the daily gain of cattle grazing early-season tallgrass prairie under an intensive-early stocking program.

Crested wheatgrass and Russian wildrye are used estensively as seeded pastures in the prairie region of western Canada. Their long-term impact on soil quality was studied at 4 sites, each including plant communities of native mixed prairie rangeland and 17- to 27-year-old monocultures of crested wheatgrass and Russian wildrye, in southern Alberta, Canada. Root mass and soil chemical properties mere determined on the soil samples collected. Native rangeland had about 7.6 times more root mass than the seeded species from the 0- to 7.5cm depth and about equivalent mass from the 7.5 to 40-cm depth. For the seeded species, root mass was significantly less between rows than within rows. Soils in the native rangeland community had significantly greater soil organic matter and lower NOs-N, chemical index, urease activity, and available phosphorus than those in the seeded pastures. Altering the plant community from native mixed prairie to either a sequence of cropping followed by an introduced grass monoculture, or directly to an introduced grass monoculture, resulted in decreased root mass and organic matter, and monosaccharide content of dry aggregates. The seeded grasses could neither return nor maintain the chemical quality of the soils in relation to that of the native rangeland.

Fecal output of range cows was determined during 2 periods of summer (period I) and late summer (period II) grazing using a constant release intraruminal Cr2O3 bolus. Chromic oxide contamination was determined by analyzing forage for Cr2O3 and by obtaining fecal samples from cows prior to bolusing. Control cows were also monitored along with the experimental cows during grazing periods. The overall herd least squares mean for fecal output during period I was lower than the expected value by 48%. Forage during period I contained an average of 55.7 microgram Cr2O3 g-1 of forage or about 45% of the daily dose of the bolus. Forage during period II contained an average of 38.3 microgram Cr2O3 g-1 of forage or about 29% of the daily dose of the bolus. Our results indicate that comparisons of fecal output least squares means by period of the year can be biased by Cr2O3 contamination of forage in pastures which have been previously used for marker studies.