There was a period during the early history of Utah when grasses in some areas grew so tall that it hid grazing cattle and sheep from view. However, mismanagement caused this to change and depleted grassland was invaded by noxious weeds, sagebrush, and pinyon-juniper. This deterioration of choice grassland to less desirable range cover was aided by the attitude of stockmen that pasture was available on a first come first serve basis. As a result of such an attitude and the unsatisfactory condition of ranges. the era of free, uncontrolled use of grazing lands came to a close with the introduction of the Taylor Grazing Act in 1934. This act provided for classification of all unappropriated and unreserved lands. Grazing districts were organized and regulations were established for the distribution of grazing permits and the setting of fees to be charged for the use of public lands (9, p.14).1

The objectives of this study were to 1) determine the effects of livestock grazing and periods of rest from grazing on infiltration and erosion rates of unchained woodland; chained, debris-in-place; and chained, debris-windrowed pinyon-juniper sites; and 2) utilize these measurements in developing guidelines for grazing management of pinyonjuniper rangelands that protect or improve the hydrologic condition of the watershed. The study was conducted on sandy loam soils in southeastern Utah during the summers of 1971 and 1972. Runoff and erosion were artificially induced from small plots by simulating rainfall with the Rocky Mountain infiltrometer. Infiltration rates, erosion rates, and selected vegetative and edaphic parameters were measured on each plot. Forage removal by clipping and soil compaction subtreatments were applied to randomly selected plots in an effort to simulate the forage removal and trampling activities of livestock. Analysis of variance techniques were used to determine the effect on infiltration and erosion rates of forage removal and soil compaction subtreatment, grazing and varying periods of rest from grazing, and chaining treatments with similar grazing histories. Multiple regression techniques were used to evaluate the influence of vegetative and edaphic factors on infiltration and erosion. Forage removal and soil compaction subtreatments had no consistent effect on infiltration rates. However, the clipping and compaction subtreatments were an instantaneous application of forage removal and soil pressure and thus may not adequately represent long term, accumulative conditions imposed by actual grazing. Areas rested from livestock grazing since 1967 had significantly higher infiltration rates than grazed areas on unchained woodland and chained, debris-in-place sites. Grazed plots consistently had the lowest infiltration rates although this lower rate was not significantly different from infiltration rates measured on areas protected from grazing since 1969 or 1971. Grazing did not consistently affect infiltration measured on chained, debris-windrowed sites. Infiltration rates increased on all three vegetative conditions as the period of rest from grazing increased. None of the 21 soil and vegetative variables included in this study were identified by multiple regression models as consistently explaining significant amounts of variation in infiltration rates. Results of this study indicate that the primary value of multiple regression models is not to predict changes that will occur in infiltration because one management alternative is selected over another, but to help explain significant differences measured between treatments. Erosion rates were not significantly affected by forage removal subtreatments, but a trend indicates that erosion increases on plots when above ground vegetation is removed by clipping. No consistent relationship between -erosion rates and soil compaction subtreatments was found. A trend toward increased erosion rates on grazed areas was found. No consistent relationship between erosion rates and the various periods of rest from grazing was recorded. Thus, any rest from grazing appears to reduce the erosion potential from pinyonjuniper sites. In summary, pinyon-juniper rangelands can be improved for livestock by chaining and seeding without causing a deterioration in watershed condition. However, to achieve these objectives, the sites to be treated must be carefully evaluated and the appropriate chaining, plant debris disposal, and seeding techniques identified. And following vegetative conversion, the areas must be properly grazed.

I assessed the paleoclimatic significance of SD values of pition pine (Pinus edulis and P. monophylla) cellulose nitrate (cn) by developing, testing and applying deterministic and empirical models, in the context of the soil-plant-atmosphere continuum. Stable isotope values of precipitation, soil water, xylem sap, leaf water, atmospheric vapor, annual and sub-annual samples of tree-ring and needle cellulose, and climatic parameters, were measured along a gradient of decreasing summer rain in the southwestern U.S. Stable isotope composition of sap indicated depth of moisture extraction. Over the growing season in New Mexico and Arizona, where monsoon rains are important, trees shifted their water use to shallower depths. In Nevada, where summer rain is scarce, trees shifted to deeper moisture late in the growing season. Evaporation altered δD and δ¹⁸O values of precipitation inputs to soil. Only after heavy monsoons did soil water and sap isotopically resemble recent precipitation. Average precipitation δD values set the baseline for δD(cn). values at each site, but interannual variations in relative humidity and precipitation amount altered wood and leaf δD(cn) values, via leaf water effects. Leaf water (1w) was evaporatively enriched by seasonal moisture stress. δD(1w). and δ¹⁸O(1w) values were strongly correlated with relative humidity on a seasonal basis, but not on a diurnal basis. Measured δ¹⁸O(1w) values fit a steady-state model, with an offset attributable to relative humidity. Measured δD(1w) values were more depleted than predicted by the model, suggesting leaf water - organic matter isotopic exchange. Biochemical fractionation (ε(B)) of hydrogen isotopes between leaf water and cellulose was inversely correlated with relative humidity. Empirical models based on linear regressions demostrated significant correlations between δD(en) values and precipitation seasonality. An El Nirio-Southern Oscillation signal (wood δD(en) values inversely related to winter precipitation amount) was found in New Mexico and Arizona. A summer rain signal (leaf δD(en) values inversely related to summer humidity) was found at all sites. δD(en) values of pirion needles in packrat middens from Sevilleta LTER, New Mexico, suggest that late Pleistocene summers were as wet as today's, and/or that storm tracks could have shifted, bringing in more tropical moisture than currently.

Thesis (M.S.)--University of Nevada, Reno, 2006. / "May 2006." Includes bibliographical references (leaves 72-76). Online version available on the World Wide Web.

Thesis (M.S.)--University of Nevada, Reno, 2005. / "May 2005." Includes bibliographical references (leaves 26-29). Online version available on the World Wide Web.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "December 2007." Includes bibliographical references. Online version available on the World Wide Web.

Thesis (M.S.)--University of Nevada, Reno, 2006. / "December, 2006." Includes bibliographical references (leaves 80-85). Online version available on the World Wide Web.

Thesis (M.S.)--University of Nevada, Reno, 2008. / "August, 2008." Includes bibliographical references (leaves 23-26). Online version available on the World Wide Web.

Objectives were (1) to evaluate the seasonal and daily use by mule deer (Odocoileus hemionus) of adjoining converted and natural pinyon pine-Utah juniper woodland (P-J) winter range, and (2) to determine the major factors influencing mule deer use of converted P-J range to provide criteria for deer management. The study was conducted on 3 sites in central, eastern, ar.d southeastern Utah between 1969-72. Data for 1969-72 on physiographic, climatic, and vegetational attributes of the three Utah study areas were related to data from approximately 10,000 deer observations, 5,000 0.01-acre pellet-group count plots, feeding observations of 1,100 deer, 220 miles of track counts on trails, and 450 radio locations of nine adult female deer. Conclusions were: (1) In the initial 12 years post-treatment, no increase in deer numbers X was correlated with P-J conversion. (2) Increasing deer use during the study was concentrated on natural P-J. (3) The bulk of the use on chainings occurred in March and April. (4) Radio telemetry indicated that, from November to May, about 55 percent of the deer within 0.5-mile of the chaining edge used the chainings at night, and 5 percent in the day. (5) Deer fed and bedded in alternate 2-hour periods. Thus, the Mayfield chainings contributed 25 to 30 percent of the deer forage, but comprised over 50 percent of the land area. (6) The greatest overwinter deer use occurred in shallow valleys and on slopes of 10-20°. Least preferred by deer were flats and hilltops. Chaining decreased the relative deer use on hilltops, increased it on hillsides, and had no effect on the use of valleys. (7) Deer use was greatest on north exposures in the natural P-J and on south exposures on chainings. (8) No edge effect existed in the initial mile of P-J away from the chaining edge, whereas, deer use of chainings declined 50 percent in the initial 0.2-mile. (9) Radio telemetry showed a mean home range radius of 0.6- mile between November and May for nine adult female deer. (10) Moon phase effected deer use on the chainings but with reversed influence between November and May. (11) Snow cover over 10 inches and wind velocity greater than 20 miles-per-hour each decreased considerably deer use of chainings. (12) An increase in shrub density increased deer use of chainings more than any other variables measured. (13) Chaining of P-J apparently decreased Cercocarpus montanus, Quercus gambelii, and Pinus edulis shrub density but increased Juni£eru~ osteosperma and Artemisia spp. Forb cover did not markedly change post-chaining, while grass cover increased by 400 percent. (14) Total forage crown cover increased 25 percent 3-12 years post-treatment. However, total palatable browse cover was less on treated than untreated range. (15) Juniperus spp., Artemisia spp. and green grasses comprised 60 to 75 percent of the over-winter diet; the remainder was composed largely of Quercus gambelii and Cercocarpus montanus. (16) Optimum tree density for deer use of P-J appears to be 50 to 100 per acre, depending upon maturity of the stand. Management recommendations are that P-J chainings should: (1) be less than 0.4-mile wide, compose no more than 20 percent of the winter range 1n a 25 year period, (2) be single chained only, (3) be confined to small valleys and gentle slopes, (4) have 20 percent slash cover, 5-10 percent grass cover, and many of the pushed-over tree tops ~eft alive, (5) be confined largely to south and west exposures, (6) be grazed in a spring- fall rotation by cattle.

Pinyon and juniper are invasive woody species which has occupied more than 47 million acres of land in Western United States. Pinyon juniper woodlands domination decreases the herbaceous vegetation, increase bare lands which in turn increases soil erosion and nutrition loss. Thus, The US Bureau of Land Management (BLM) has focused on harvesting these woody species to make room for herbaceous vegetation. The major application of harvested pinyon-juniper (PJ) is low value firewood. Thus, there is a need to develop new high value products from this woody biomass to reduce the cost of harvesting. In this study pyrolysis was carried out to investigate the feasibility of converting pinyon juniper biomass to value added products. The first part of the study was focused on biomass characterization, and effect of biomass type on product yields. The second part focuses on optimization of process parameters on product yields. The third part focuses on catalytic pyrolysis for improving the quality of bio-oil. In this study it has been shown that pinyon juniper biomass could be effectively used as biomass in fast pyrolysis and red mud, an industrial waste could be used as catalyst in catalytic pyrolysis to improve the quality of the bio-oil.