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All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

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Articles 1171 - 1200 of 1427

Full-Text Articles in Physical Sciences and Mathematics

Structural Geology Of The Southern Part Of Clarkston Mountain, Malad Range, Utah, Wayland E. Gray May 1975

Structural Geology Of The Southern Part Of Clarkston Mountain, Malad Range, Utah, Wayland E. Gray

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The mapped area, in north-central Utah, is located west of Clarkston, Utah. It includes the southern part of Clarkston Mountain and part of the Junction Hills, which extend southward from Clarkston Mountain. The area is represented on the southeastern part of the Portage quadrangle, Utah-Idaho, and the southwestern part of the Clarkston quadrangle, Utah-Idaho. It measures about 8.3 miles in the east-west direction and 4.0 miles in the north-south direction.

The southern part of Clarkston Mountain consists of stratigraphic units that range in age from Cambrian to Silurian. The Nounan Formation of Cambrian age is the oldest. The St. Charles …


Evaluating The Availability Of Organic Nitrogen In Soils, Saleh M. Romaih May 1975

Evaluating The Availability Of Organic Nitrogen In Soils, Saleh M. Romaih

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The main objective of this study was to evaluate the organic N in silty clay loam soil as an indicator of soil fertility. The incubation method was used in this study. The NO3 -N, the total N percent, and the organic matter were determined. The soil which was used in this study came from Evans Research Farm. The samples were taken from two different N experiments which were adjacent to each other. The soil samples were taken in October-November, 1973, after the crop had been harvested. These two experiments had different cropping histories.

The results of the first experiment …


Petrology Of The Upper Nounan - Worm Creek Sequence, Upper Cambrian Nounan And St. Charles Formations, Southeast Idaho, Lillian Donley Wakeley May 1975

Petrology Of The Upper Nounan - Worm Creek Sequence, Upper Cambrian Nounan And St. Charles Formations, Southeast Idaho, Lillian Donley Wakeley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The upper member of the Nounan Formation and the Worm Creek Member of the St. Charles Formation, both late Cambrian in age, were studied in the Bear River Range and the Fish Creek Range in southeast Idaho. Lithology and sedimentary structures of these units were compared with characteristics of similar modern sediments and ancient rocks, to determine the environments of deposition and effects of diagenesis for the interval studied.

On the basis of widely traced marker horizons, the two-member interval is divided into three parts, with parts 1 and 2 comprising the upper member of the Nounan Formation, and part …


Geology Of Southern Part Of The James Peak Quadrangle, Utah, Jan G. Blau May 1975

Geology Of Southern Part Of The James Peak Quadrangle, Utah, Jan G. Blau

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The mapped area, in north-central Utah, is centered about 22.6 miles south of Logan, Utah. It measures about 3.8 miles in the north-south direction and 6.6 miles in the east-west direction. Stratigraphic units of Precambrian and Cambrian age underline most of the area. The Precambrian units are as follows: (1) Maple Canyon Formation, (2) Kelley Canyon Formation, (3) Orthoquartzite unit, (4) Argillite unit, (5) Mutual Formation, and (6) Volcanic unit. The Brigham Formation, which overlies the Precambrian volcanic unit, is probably of Cambrian age; however, the lower part may be Precambrian. The overlying Cambrian carbonate unit is not differentiated. The …


Residual Nitrogen As It Affects Soil Fertility Under Irrigated Agriculture In A Tropical Wet-Dry Climate, Don Carlos Kidman May 1975

Residual Nitrogen As It Affects Soil Fertility Under Irrigated Agriculture In A Tropical Wet-Dry Climate, Don Carlos Kidman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the Zapotitan Valley near San Andres, El Salvador, Central America, an experiment was conducted to determine the availability of residual soil N to corn grown during the rainy season. This was an extension of an experiment conducted during the preceding dry season. The variables of the dry season experiment were irrigation method, crop, and rate of fertilizer N application. Soil NO3-N and NH4-N were determined by soil sample analysis to a soil depth of 120 cm by 30 cm depth increments. The samples were taken at the end of the dry season experiment and again …


Distribution Of Available Phosphorus In The Subsoil Of Selected Pedons Of The Warm Springs Series, Duane Altman Lammers May 1975

Distribution Of Available Phosphorus In The Subsoil Of Selected Pedons Of The Warm Springs Series, Duane Altman Lammers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Warm Springs soil series which contained variable amounts of subsoil available (sodium bicarbonate extractable) phosphorus was studied to explain the variability and distribution of the NaHCO3-P in the subsoil. Four pedons ranging in subsoil NaHCO3-P from less than 10 ppm to greater than 30 ppm were selected in an area of less than 200 ha located on a nearly level, low lake terrace east of the Great Salt Lake in Weber County, Utah.

The morphology of each pedon was described in the field and samples collected from each genetic horizon or contrasting layer. Each soil …


A Model To Predict The Effect Of Salinity On Crop Growth, Stuart W. Childs May 1975

A Model To Predict The Effect Of Salinity On Crop Growth, Stuart W. Childs

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A model is developed to predict the effects of soil salinity on crop growth. As an outgrowth and extension of the modelling efforts of Nimah and Hanks (1973a) and Gupta (1972), this model makes these principal assumptions in order to arrive at a quantitative relationship: 1) relative yield for a growing season is directly related to the ratio of actual and potential transpiration. 2) Water uptake by plants is in response to the water potential gradient between the plant at the soil surface and the soil surrounding the plant roots. 3) the effect of salinity on crop growth is solely …


The Influence Of Roots On The Accuracy Of Soil-Moisture Measurements Taken With A Neutron Moisture Meter, Terry L. Andreessen May 1975

The Influence Of Roots On The Accuracy Of Soil-Moisture Measurements Taken With A Neutron Moisture Meter, Terry L. Andreessen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The effects of roots on soil-moisture measurements taken with a neutron probe were studied. These effects were observed under three different soil-moisture conditions, with different sized roots, and with varying distances between the access tube and root. The moisture conditions used were air dry, field capacity, and saturated.

Large roots can greatly affect neutron soil-moisture measurements when the access hole is drilled through the root. Positive errors as large as 52 percent were found when the soil moisture was at field capacity. With dry and saturated conditions positive errors of 43 percent and 38 percent respectively, were found.

In most …


Characteristics And Genesis Of The Parleys And Mendon Soils Series In Northern Utah, Khalid I. Al-Amin May 1974

Characteristics And Genesis Of The Parleys And Mendon Soils Series In Northern Utah, Khalid I. Al-Amin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The study was designed to test the genetic theory of soil development of two soils derived from different geological material, but developed under conditions of similar climate, topography, biological activity, and age. An attempt was made to relate the soils characteristics to their present classification. Parleys and Mendon series which developed from Bonneville and Salt Lake Formation, respectively, were selected for that purpose. Along the east side of Cache valley, two pedons representing each of the studied series were selected to have similar soil formers except for their parent material.

Evidently, these studied soils have been developed from different heterogenous …


Nutrition Of Sheep Grazing Foothill Big Game Range In Spring, Kurt J. Kotter May 1974

Nutrition Of Sheep Grazing Foothill Big Game Range In Spring, Kurt J. Kotter

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Sheep with esophageal fistulas were used to determine the daily intake, nutritive content and digestibility of forage at three periods and two stocking intensities during the spring of 1972 on a typical foothill range in northern Utah.

Heavy grazing under a season-long regime did not influence the concentrations of dietary chemical components when compared to moderate grazing; however, it did depress the digestibility of cellulose and organic matter. There was a significant decline in the dietary chemical components due to forage maturation. Digestibility of organic matter and cellulose were significantly higher in the early spring as compared to late spring. …


Environmental Analysis Of The Upper Cambrian Nounan Formation, Bear River Range And Wellsville Mountain, North-Central Utah, Larry L. Gardiner May 1974

Environmental Analysis Of The Upper Cambrian Nounan Formation, Bear River Range And Wellsville Mountain, North-Central Utah, Larry L. Gardiner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Nounan Formation in north-central Utah thickens northward from 696 feet near Causey Dam to 1147 feet at High Creek in the Bear River Range, and northwestward to 1149 feet at Dry Canyon in Wellsville Mountain. The basal contact of the Nounan Formation is sharp, but dolomite extends irregularly downward into limestones of the Bloomington Formation as much as 6 feet.

The Nounan Formation is divided into three members based on lithologic characters: (1) a lower member composed of dark, medium-crystalline dolomite; (2) a middle member composed of white, coarse-crystalline dolomite with tongues of dark dolomite; and (3) an upper …


Determination Of Crop Production Functions As Related To Soil Moisture And Nitrogen, James W. Bauder May 1974

Determination Of Crop Production Functions As Related To Soil Moisture And Nitrogen, James W. Bauder

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Soil moisture and nitrogen are often the primary controlling factors of crop production. Production functions are valuable in describing crop responses to such controlling factors. Such functions are also needed for determining the economic reliability of crop production.

Soil moisture and nitrogen fertilizer were maintained at various levels to determine the response of field corn to these controlling factors. A conventional split plot design, a continuous function experimental design, and a confined barrel plot design were used to obtain data for determining production functions.

The complete factorial, conventional split plot data was successfully used to generate reliable production functions in …


Phosphate Exploration And Property Evaluation In Southeastern Idaho, Illustrated By The Dry Valley Area, James Simon Spalding May 1974

Phosphate Exploration And Property Evaluation In Southeastern Idaho, Illustrated By The Dry Valley Area, James Simon Spalding

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The western phosphate field produced about 15 percent, in 1970, of the nation's domestically consumed phosphate rock and contains an estimated 58 percent of the nation's indicated phosphate reserves. The central portion of the western phosphate field, which contains the Dry Valley area of southeastern Idaho, encompasses the greatest amount of mineable phosphate reserves in the smallest geographic area within the western field.

Exploration of properties in the area should follow an orderly sequence of literature search, area reconnaissance, detailed target appraisal, and detailed three-dimensional sampling to effectively evaluate each property. Present exploration techniques include topographic analysis, vegetative investigation, profile …


A Study Of The Radiation Quality Under Plant Canopies In The Wave Range 0.4 To 2.5 Microns, Nolasco G. Baldazo May 1974

A Study Of The Radiation Quality Under Plant Canopies In The Wave Range 0.4 To 2.5 Microns, Nolasco G. Baldazo

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The spectral distribution of the global radiation from 0.4 to 2.5 microns penetrating deciduous and coniferous canopies were measured during clear days between 10 a.m. and 2 p.m. using a double-quartz monochromator.

In the visible region (0.4 to 0.7 micron) the average relative spectral transmissions under both canopies are about one percent beginning at 0.4 micron and decreasing to about half a percent at 0.67 micron. There is only a small peak in the green (0.55 micron) transmission under deciduous stands while there is none under coniferous canopies. The slightly higher transmission in the blue (0.4 micron) is attributed to …


A Theoretical Proton-Proton Pair Production Cross-Section Calculation, Jay W. Phippen May 1974

A Theoretical Proton-Proton Pair Production Cross-Section Calculation, Jay W. Phippen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The calculation of both electron-pair and muon-pair production cross-sections was made using Feynman's quantum electrodynamics. Pseudo-scaler coupling was used between the nucleons and vector coupling was used between the photon and the Fermions. The protons were considered as Dirac particles and radiative corrections were omitted.

Eight fourth-order Feynman-Dyson diagrams were used. The subsequent sixty-four TRACES were reduced to seven basic topologically different TRACES. From the seven basic TRACES, it was possible to generate the sixty-four TRACES by the proper permutations of the variables.

With the mathematics and the corresponding computer programs written down, data (energies and momenta which represent the …


A Comparative Analysis Of The Use Of A Markov Chain Versus A Binomial Probability Model In Estimating The Probability Of Consecutive Rainless Days, Jack Wilfred Homeyer May 1974

A Comparative Analysis Of The Use Of A Markov Chain Versus A Binomial Probability Model In Estimating The Probability Of Consecutive Rainless Days, Jack Wilfred Homeyer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Markov chain process for predicting the occurence of a sequence of rainless days, a standard technique, is critically examined in light of the basic underlying assumptions that must be made each time it is used. This is then compared to a simple binomial model wherein an event is defined to be a series of rainless days of desired length. Computer programs to perform the required calculations are then presented and compared as to complexity and operating characteristics. Finally, an example of applying both programs to real data is presented and further comparisons are drawn between the two techniques.


The Dynamics Of Root Growth And The Partitioning Of Photosynthates In Cool Desert Shrubs, Osvaldo Alberto Fernandez May 1974

The Dynamics Of Root Growth And The Partitioning Of Photosynthates In Cool Desert Shrubs, Osvaldo Alberto Fernandez

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study addresses the nature of physiological and phenological evolutionary strategies of root growth dynamics and energy allocation followed by Atriplex confertifolia, Ceratoides lanata, and Artemisia tridentata growing in their natural cool desert environment.

Root observation chambers with inclined Plexiglass windows were installed in monospecific desert communities of Atriplex confertifolia, Ceratoides lanata and Artemisia tridentata. Soil temperature and water potential measurements taken immediately adjacent to the observation windows indicated a minimal disturbance was caused by the presence of these chambers. For the three species initiation of root growth was observed before initiation of shoot activity, furthermore, active root growth extended …


An Evaluation Of In-Stream Structures Designed To Provide Fish Habitat, Charles H. Call Jr. May 1974

An Evaluation Of In-Stream Structures Designed To Provide Fish Habitat, Charles H. Call Jr.

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In-stream concrete structures were studied through model tests and river tests. The model studies indicated that four designs provided good habitat in the model stream. These structures were the inverted weir, the "V" structure, the slab with legs and the cylinder. Through the river studies it was determined that these structures did not influence enough of the total river area to be effective in providing good fish habitat. Also an appreciable amount of yearly maintenance would be required to free the structures from silting in, debris, and vandalism. The slab with legs was the only promising structure.


Comparison Of Transition Matrices Between Metropolitan And Non-Metropolitan Areas In The State Of Utah Using Juvenile Court Data, Sung-Ik Song May 1974

Comparison Of Transition Matrices Between Metropolitan And Non-Metropolitan Areas In The State Of Utah Using Juvenile Court Data, Sung-Ik Song

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this paper is to use Markov Chains for the study of youths referred to the juvenile court in the metropolitan and non-metropolitan areas of the state of Utah.

Two computer programs were written for creating case histories for each person referred to the court and for testing for the significance of the difference among several transition matrices.

Another computer program, which was written by Soo Hong Uh, was used for analyzing realizations of a Markov chains up to the 4th order; a third computer program, originally written by David White, was used for interpreting Markov chains.

The …


An Intensive Edaphological Characterization Of The Soils Of Malambito Experimental Station And Its Implications In Future Agricultural Research, William L. Rubink May 1973

An Intensive Edaphological Characterization Of The Soils Of Malambito Experimental Station And Its Implications In Future Agricultural Research, William L. Rubink

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Malambito Experiment Station, in the Atlántico III project area, Department of Atlántico, Colombia, had almost no quantitative edaphological data on which to base agricultural research. Unexplainably low general yields as well as problem areas of deficient plant growth only confounded the results of field plot experiments. Intensive soil sampling and subsequent measurements of pH, ECe of the saturation extract, and the four major cations disproved the previous suggestions that the crop growth problems were related to saline, sodic, or degraded soil conditions. The Ca/Mg+K+Na ratio, although significant when correlated with plant height, was sufficient explanation for only a small …


Structural Geology Of The Northern Part Of Clarkston Mountain, Malad Range, Utah-Idaho, Steven Mark Burton May 1973

Structural Geology Of The Northern Part Of Clarkston Mountain, Malad Range, Utah-Idaho, Steven Mark Burton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The northern part of Clarkston Mountain, in northern Utah and southern Idaho, is located about 23 miles northwest of Logan, Utah. It extends across the Malad Range from Malad Valley on the west to Cache Valley on the east. The mapped area measures 4.8 miles in the north-south direction and 6.8 miles in the east-west direction.

The Brigham Formation of Cambrian age is the oldest exposed stratigraphic unit. It consists mainly of quartzite. Younger Cambrian units include the Langston, Ute, Blacksmith, Bloomington, Nounan, and St. Charles Formations. The Garden City Formation of Ordovician age is the youngest Paleozoic unit. The …


Mesoscale Atmospheric Circulation And Diffusion Characteristics, Ronan I. Ellis May 1973

Mesoscale Atmospheric Circulation And Diffusion Characteristics, Ronan I. Ellis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Constant volume superpressure pillow balloons were flown over a mountain valley downwind from a sharp ridge line. Balloon trajectories revealed and atmospheric soundings confirmed a persistent turbulently mixed adiabatic layer over the valley at approximately ridge top height except in the immediate lee of the ridge where strong vertical motions were observed. Temporary stationarity of the relative mesoscale turbulence was found to exist on a time scale exceeding 4 hours. Power spectrum analysis of component relative velocities showed greater variance in lower wave numbers and anisotropy in mesoscale turbulence. Eddy diffusivity coefficients for turbulence above the ridge height were K …


Trout Movements In A Small Mountain Stream, Thomas Mark Twedt May 1973

Trout Movements In A Small Mountain Stream, Thomas Mark Twedt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Five groups of 400 hatchery rainbow trout, (Salmo gairdneri), were stocked in a small, mountain stream at 3-week intervals from June to September, 1972. A fish trap captured any fish moving out of a 500 m study section.

Fish began moving at high levels during the first day of each stocking and continued at high rates for 5-8 days (Early Phase), after which movement decreased to low levels for 6-9 days (Late Phase). Early Phase fish moved primarily at night, possibly due to their disoriented state and high subjectivity to stream conditions. Fish moving during Late Phase did …


Effects Of Exercise On Serum Lactate Dehydrogenase Activity Of Catchable-Size Hatchery Rainbow Trout, Salmo Gairdneri, Gerlad T. Klar May 1973

Effects Of Exercise On Serum Lactate Dehydrogenase Activity Of Catchable-Size Hatchery Rainbow Trout, Salmo Gairdneri, Gerlad T. Klar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Effects of exercise and the relative condition of exercised fish were viii evaluated for two strains of rainbow trout. Circular tanks fitted with a paddle were used to continuously exercise the fish and a stamina tunnel was used to evaluate the condition of exercised trout. Trout were exercised continuously at one fish-length per second and one-half fish length per second. Serum LDH activity in Shephard-of-the-Hills (Missouri) rainbow trout acclimated to 10 C increased two fold during the first four days of exercise. Serum LDH activity returned to control levels by the tenth day of exercise. Serum LDH activity in Shephard-of-the-Hills …


Internal Water Potential Of An Engelmann Spruce Stand In Relation To Soil And Atmospheric Factors, Richard L. Meyn May 1973

Internal Water Potential Of An Engelmann Spruce Stand In Relation To Soil And Atmospheric Factors, Richard L. Meyn

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The primary objective of this study was to determine the degree of correlation between internal water potential of Engelmann spruce trees and selected environmental factors. The secondary objective of the study was to determine the effect of summer precipitation, both in meadow and forested sites, on the soil drying cycle.

Four study plots (each roughly 154 square meters) under spruce cover and two study plots (100 square meters) in a small meadow were established. At each spruce plot, a thermocouple psychrometer was installed at one meter above the ground on the north side of three selected, mature Engelmann spruce trees. …


Autecological Life History Studies Of Two Geraniums, Geranium Richardsonii And Geranium Nervosum, Becky Lee Green May 1973

Autecological Life History Studies Of Two Geraniums, Geranium Richardsonii And Geranium Nervosum, Becky Lee Green

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Two perennial species of wild geranium (Geranium nervosum Rydb. and G. richardsonii Fisch, and Trautv, [Geraniaceae]) which grow throughout the mountainous regions of western North America were studied to determine the factors influencing the life stage development and distribution of these plants. Attempts were also made to provide some information to assist in the taxonomy of this genus.

Geranium richardsonii is found in wet meadows and along streambanks throughout its distribution. Geranium nervosum frequents rocky hillsides and drier meadows throughout its range.

Seeds of G. nervosum had 65%, germination in the stratification pretreatment. Geranium richardsonii seeds required scarification to …


An Investigation Of Cluster Analysis, John C. Klingel May 1973

An Investigation Of Cluster Analysis, John C. Klingel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Three cluster analysis programs were used to group the same 64 individuals, generated so as to represent eight populations of eight individuals each. Each individual had quantitative values for seven attributes. All eight populations shared a common attribute variance-covariance matrix.

The first program, from F. J. Rohlf's MINT package, implemented single linkage. Correlation was used as the basis for similarity. The results were not satisfactory, and the further use of correlation is in question.

The second program, MDISP, bases similarity on Euclidean distance. It was found to give excellent results, in that it clustered individuals into the exact populations from …


Petrology And Geochemistry Of The Morrison Formation, Dinosaur Quarry Quadrangle, Utah, Sue Ann Bilbey May 1973

Petrology And Geochemistry Of The Morrison Formation, Dinosaur Quarry Quadrangle, Utah, Sue Ann Bilbey

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Mineralogical and petrographic analyses of the upper Jurassic - lower Cretaceous units in the vicinity of the Dinosaur National Monument quarry near Jensen, Utah, have elucidated their characteristics and the locations of formational boundaries. The lower part of the Morrison Formation is distinguished by a decreased amount of illite and an increased amount of kaolinite. In contrast, the underlying Curtis Formation contains an approximately equal mixture of illite and kaolinite. The lower Salt Wash Member and the upper Brushy Basin Member of the Morrison are both lithologically and mineralogically identifiable in this area. Above the boundary between the two, kaolinite …


A Measure Of The Amount Of Phosphate Adsorption And The Rate Of Release Of Indigenous Phosphate From A Desert Soil, Robert Lindsey Evans May 1973

A Measure Of The Amount Of Phosphate Adsorption And The Rate Of Release Of Indigenous Phosphate From A Desert Soil, Robert Lindsey Evans

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The capacity of a calcareous desert soil, Thiokol silt loam, to retain natural, as well as added, orthophosphate-P was measured by equilibrium adsorption employing a batch technique and evaluated using the two-slope Langmuir adsorption isotherm. From these data, corrected to account for indigenous soil P, a hypothesis was formulated as to the nature of retention of P by the soil, including the identification of two interfacial reactions involving P, and a value calculated for the adsorption maximum as defined by the Langmuir isotherm equation for P with soil at each of two soil depths and three constant temperatures within the …


Bromegrass Productivity In Relation To Precipitation, Shrub Canopy Cover And Soil Nitrogen Content, Lawrence G. Kline May 1973

Bromegrass Productivity In Relation To Precipitation, Shrub Canopy Cover And Soil Nitrogen Content, Lawrence G. Kline

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In seasons of above normal precipitation, populations of annual weedy species increase in great abundance in semi-arid desert plant communities. These increases in biomass tie up a considerable portion of the available nitrogen of such ecosystems and may depress subsequent annual grass germination.

A big sagebrush-annual bromegrass plant community was irrigated to simulate a spring growth period of abundant precipitation amenable to annual bromegras s productivity. Productivity and nitrogen content parameters were monitored throughout the spring and summer to evaluate the short and potential long term effects of this seasonal increase in "precipitation".

Irrigation increased annual bromegrass productivity almost 50 …