When crested wheatgrass (Agropyron desertorum) grows in mixture with sagebrush (Artemisia tridentata), its production declines. Its production increases when grown in mixture with fourwing saltbush (Atriplex canescens), according to previous reports. This study investigated soil water extraction and potassium (K) nutrition of the two shrubs to identify possible causes of the differential responses of crested wheatgrass. Crested wheatgrass had reduced, rather than increased, nitrogen (N) and K yield in mixture with fourwing saltbush. No differences in N and phosphorous (P) concentrations were observed between sagebrush and fourwing saltbush, but fourwing saltbush had a much higher K concentration and returned nearly twice as much K to the soil as sagebrush by throughfall and litterfall. Throughfall additions were much greater than those from litterfall. AK-fertilization/water-stress, two-factor greenhouse experiment was conducted with crested wheatgrass. High- and medium-K-fertilization treatments had highest tissue K concentration, but biomass yield was reduced in waterstressed plants with high K-fertilization. A difference of 1.56 MPa in osmotic adjustment was observed between waterstressed plants with high K-fertilization and irrigated, low-K-fertilization plants. These results suggest that K accumulation in fourwing saltbush may be a factor for enhanced crested wheatgrass productivity. Crested wheatgrass grown in mixture with fourwing saltbush had lowered predawn and mid-day xylem water potentials compared with monoculture and sagebrush mixture plots, but no other treatment differences were observed for any species. Fourwing saltbush monoculture plots had the most uniform water extraction rates and may compete less for water than sagebrush when crested wheatgrass extraction rates are highest.

This research was conducted on three study areas on elk winter ranges in Northeast Oregon. One was on the Starkey Experimental Forest and Range and the others were in the same vicinity. Plant appendages, spring and fall defoliation and fall growth of bluebunch wheatgrass were evaluated in terms of quality of nutrient content during September through April of 1986-87 and 1987-88. Four treatments were applied. Plants were clipped to a 2.5 cm and 7.6 cm stubble height in the spring before the boot stage of phenological development; plants were clipped to a 7.6 cm stubble height in the fall after plant maturity in September; plants were not clipped during the year. Percent crude protein, dry matter digestibility (DMD), acid detergent fiber (ADF), and lignin were evaluated monthly. Samples from the four treatments were also analyzed from October to April to determine monthly changes in nutrient contents. Production of growth from all treatments was measured in October and March each year. Leaf material had higher percent crude protein and DMD, with lower percent ADF and lignin than the inflorescence and culm. The third leaf (the youngest plant material) had the highest nutrient value of all appendages. The culm and inflorescence values were not statistically different. Growth following spring defoliation treatments produced higher percent crude protein and DMD (P<.05), with a lower percent ADF and lignin than non-treated plants in both years. This was particularly pronounced during 1986 when precipitation in late summer initiated fall growth. Growth following spring defoliation and bluebunch wheatgrass not defoliated did not produce crude protein or DMD values sufficient to meet minimum dietary maintenance requirements for elk. Fall precipitation adequate to promote fall growth occurred only in 1986. Growth after fall defoliation had the highest percent crude protein and DMD with the lowest ADF and lignin values of all vegetation sampled. However, without 3-5 cm of late summer/early fall rains, fall growth does not occur. This happened in 1987. When growth does occur in fall the quality of the growth exceeds the minimum dietary maintenance requirements for elk. Freezing and thawing of fall growth plant material had minimal effect on forage quality. There were differences (P<.05) between the monthly values for percent crude protein and ADF starting in October and ending in April. However, the percent DMD and lignin from October to April were not different (P<.05). / Graduation date: 1993

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 22, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Ecology, Department of Biological Sciences, University of Alberta. Includes bibliographical references.

Thesis (Ph.D.)--University of Western Australia, 2007.

Rehabilitation of deteriorated and abused range lands is being accomplished with greater success each year by the aid of better methods of seeding which include seedbed preparation, intensities of seeding, implements for planting and improvised methods of eliminating competition. Much more information is needed however in order to recommend suitable methods and species for seeding various vegetation types and genes with reasonable reliability. Throughout the arid and semi-arid range lands, moisture is the principal factor limiting satisfactory seedling establishment. Special attention should therefore be given to more efficient utilization of the moisture supply. Closely related species of species with similar growth characteristics are said to compete for more water, for space and for nutrients; therefore, studies dealing with the effect of spacing and intensity of seeding upon seedling establishment are of paramount importance.

Alkali land occurs adjacent to nearly every extensively irrigated area. Much of this land is too alkaline to produce profitable crops. Each year thousands of acres or land are going out of production because or increasing alkalinity. This presents one or the most acute problem which confronts irrigation agriculture today.

Screening populations for development into released plant materials can be done inexpensively and in a timely manner. A common approach has been to quantify the amount of shoot dry mass produced as a surrogate for competitiveness. Besides dry mass production , other morphological characteristics have been employed , but physiological parameters have received less emphasis. Dry mass production may be an important characteristic, but identifying the traits responsible can be just as imperative . Populations with greater drought tolerance may be less impacted by competition for water from weeds, which could lead to greater establishment of desirable grasses on disturbed landscapes. The objective for chapter 2 was to evaluate the effects of cheatgrass competition on the growth and water relations of three Snake River wheatgrass (Elymus wawawaiensis) populations and two bluebunch wheatgrass (Pseudoroegneria spicata) populations in the seedling stage in a greenhouse setting. The treatments were 1) containers with a single wheatgrass plant or 2) containers with one wheatgrass and one cheatgrass plant. Containers were watered gravimetrically to 11.5% soil-water content, regard less of treatment, every few days until harvested on day 35. Cheatgrass competition reduced root dry mass, shoot dry mass, leaf area, leaf number, tiller number, xylem pressure potential, and stomata} conductance. The bluebunch wheatgrass populations generally had more negative xylem pressure potential, higher stomata! conductance, and higher shoot dry mass, while the Snake River populations had higher specific leaf area and less negative xylem pressure potentials . The objective for chapter 3 was to evaluate the effects of planting density on the growth and water relations over a 2-year period among five Snake River wheatgrass populations, one thickspike wheatgrass (Elymus lanceolatus) population , and three interspecific hybrids. High (25 plants/m 2 ) and low-density (7.8 plants/m2) plots of each grass were transplanted to Millville, Utah in the spring of 2005 and 2006 intended to generate low and high resource availability environments, respectively. Thickspike wheatgrass had the highest shoot dry mass and least negative xylem pressure potential , the hybrids were intermediate, and the Snake River wheatgrasses were least productive and more water stressed. The primary benefit of this thesis will be through identifying the potential for developing these populations into improved plant materials and releasing them for commercial use in degraded rangelands across the Intermountain West. These new plant materials may also help transition damaged rangelands towards more desirable stable states composed of lower abundances of invasive annual grasses.

Pseudoroegneria spicata and Elymus wawawaiensis are two native perennial bunchgrasses of North America's Intermountain West. Frequent drought, past overgrazing practices, subsequent weed invasions, and increased wildfire frequency have combined to severely degrade natural landscapes in the region, leading to a decline in the abundance of native vegetation. Being formerly widespread throughout the region, P. spicata is a favorite for restoration purposes in the Intermountain West. Elymus wawawaiensis, which occupies a more restricted distribution in the Intermountain West, is often used as a restoration surrogate for P. spicata. However, since most restoration sites are outside the native range of E. wawawaiensis and as the use of native plant material may be more desirable than a surrogate, the use of E. wawawaiensis as a restoration plant material has been somewhat controversial. The main goal of my research was to identify plant materials of these species with superior seedling growth, drought tolerance, and defoliation tolerance, traits that may contribute to enhanced ecological function in restored rangeland plant communities. I conducted a growth-chamber study to evaluate morphological and growth-related traits of germinating seedlings of these two species. My study suggested that, while the two bunchgrasses are similar in many ways, they display fundamentally different strategies at the very-young seedling stage. While P. spicata exhibited greater shoot and root biomass to enhance establishment, E. wawawaiensis displayed high specific leaf area (SLA) and specific root length (SRL), two traits commonly associated with faster growth. According to the eco-physiology literature, plants with greater stress tolerance display lesser growth potential. However, my greenhouse study showed that E. wawawaiensis was relatively more drought tolerant than P. spicata, despite higher expression of growth-related traits, e.g., SLA and SRL. While the two species displayed similar water use efficiency when water was abundant, E. wawawaiensis was also more efficient in its water use when drought stress was imposed. In a field study, I found E. wawawaiensis to be twice as defoliation tolerant as P. spicata. This study showed that P. spicata is typically more productive in the absence of defoliation, but E. wawawaiensis was more productive after defoliation due to its superior ability to recover and hence is a better candidate for rangelands that will be grazed. Hence, my study showed that E. wawawaiensis, despite being regarded as a surrogate for P. spicata, exhibits superior seedling establishment, drought tolerance, and defoliation tolerance. Therefore, E. wawawaiensis has advantages as a restoration species for the Intermountain West.

Cheatgrass is an invasive weed that has come to dominate large areas of the western United States. Once an ecosystem has been converted to a cheatgrass monoculture, it is extremely difficult to restore native vegetation. Cheatgrass negatively impacts wildlife and increases wildfire frequency and intensity. Understanding how cheatgrass so effectively invades western ecosystems is essential to turning the tide of invasion. One possible key to cheatgrass’ success is alteration of soil nutrient cycling. The goal of this study is to explore how nitrogen (N) may accumulate in cheatgrass soils via redistribution of N within soil N pools. To accomplish this we investigated soil N cycling in soils underneath cheatgrass and crested wheatgrass. We used a 15N isotope tracer to determine the contribution of root exudates to soil N pools. During the 1-week 15N tracer experiment, cheatgrass roots exuded more than twice as much N (0.11 mg N kg-1 soil d-1) as crested wheatgrass roots (0.05 mg N kg-1 soil d-1). We propose that exudation of high N content root exudates leads to the changes in soil N pool size and transformation rates commonly observed in soils under cheatgrass. This research uses a simple and relatively inexpensive isotope tracer to shed light on mechanisms by which invasive plants may alter soil processes. By understanding these mechanisms we may be able to develop strategies for better managing cheatgrass invasion.

The free-roaming ruminant requires energy for the demands of vii grazing, traveling and thermoregulation that are not required by its confined counterpart. Literature estimates of these additional costs range from 10 to 170 percent above maintenance. The uncertain magnitude of this increased demand and the factors that contribute to it impede the ability of the rangeland ruminant nutritionist to establish guidelines for the energy requirements of the free-roaming herbivore. This study was designed to estimate the energy expenditure of yearling Angus heifers while grazing a declining supply of available crested wheatgrass forage (Agropyron cristatum) on rangeland in west-central Utah. Free-ranging energy expenditure was estimated twice for four heifers during each of five ten-day periods during June, July August and early September, 1979. These estimates were obtained using the carbon dioxide entry rate technique. In addition, total fecal output, dietary crude protein and dietary in vitro organic matter digestibility were estimated for animals grazing the 20- hectare crested wheatgrass pasture. From these data, daily forage intake was calculated. The level of available forage during each period was estimated using the ocular weight-estimate technique applied on forty 1 m2 circular plots. Energy expenditure was estimated as 161 (with a confidence interval of ±43) kcal·kg body weight-.75.d-1 (n=10), and was independent of the decline in available forage from 880 to 284 kg dry matter·hectare-1 that occurred over the course of the grazing season. Daily intake was 54.5 grams (organic matter basis) per unit body weight.75 for the 305 kg heifers. Daily intake was independent of the supply of available forage. During early July, 1980, crested wheatgrass was harvested as hay and fed to 260 kg yearling Angus heifers in metabolism stalls in a thermoneutral and constantly illuminated laboratory. Daily feeding levels were set at 54.5 grams (organic matter basis) per unit body weight.75. Energy expenditure under these conditions was estimated as 111 (±12) kcal·kg body weight-.75·day-1 , 6 kcal per unit body weight.75 greater than the mean estimate of the fasting metabolism rate. The latter estimate was obtained following a 48-hour fast. These estimates of maintenance and fasting metabolism were combined to provide a mean estimate of 110 (±10) kcal·kg body weight-.75·day-1 (n=14). Of the 45 percent (51 kcal·kg body weight-.75·day-1) increase in the estimated energy expenditures by heifers under free-roaming conditions, 50 percent was attributed to the energetic cost of grazing. A daily average 9.2 hours were spent in this activity. The energetic cost of grazing was assumed as 0.82 kcal·kg body weight-1·hour-1 spent grazing. Daily travel was estimated as 3.9 km at an assumed energetic cost of 0.58 kcal·kg body weight-1·km-1. This accounted for a 20 percent estimated increase in energy expenditure. Average daily temperatures were generally between 12°C and 30°C and thermoregulatory demands were not considered as a substantial energetic expense. The remaining 30 percent (12 kcal) of the additional increment due to free-roaming conditions could not be explained.