Ecology and Evolutionary Biology Commons^™

Competitive Interaction In Plant Populations Exposed To Enhanced Uv-B Radiation, Fred M. Fox

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Competitive balance and changes in individual plant growth parameters of eight pairs of plant species exposed to enhanced UV-B irradiation were determined under field conditions simulating ozone reductions of about 0.08 atm·cm. The levels of irradiance represented ozone decreases of about 25-30 percent from approximate ambient ozone concentrations for high solar altitudes on clear days during the study. A method for calculating and statistically analyzing relative crowding coefficients was developed and used to evaluate the competitive status of the species pairs sown in a modified replacement series. The effect of UV-B irradiance was generally detrimental to plant growth, and was …

Aspects Of The Life History Of Three Catostomids Native To The Upper Colorado River Basin, Charles W. Mcada

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The distribution, abundance and life history were studied for three catostomids -- the razorback sucker (Xyrauchen texanus), the flannel-mouth sucker (Catostomus latipinnis), and the bluehead sucker (Catostomus discobolus) -- all native to the upper Colorado River basin. The razorback sucker has declined in abundance due to man's impact upon the system and it has been recommended that this species be listed as ''threatened" on the U. S. Department of the Interior's list of Threatened or Endangered species [Personal corrmunication, G. C. Kobetich, U. S. Fish and Wildlife Service, Las Vegas, Nevada]. During this investigation, …

Relationships Of Vegetation To Environment In Canyonlands National Park, Walter Lee Loope

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The vegetation of Canyonlands National Park, Utah, has been described from 157 samples located throughout the Park. Species frequency, density and cover were recorded along with measurements of soil thickness, slope, aspect, elevation and geologic substrate at each site. Measurements of soil texture, pH, and electrical conductivity were taken for a representative subsample. A map of the vegetation of the Park was made by relating the sample points to their corresponding spectral signatures on vertical aerial photographs and locating boundaries between vegetation units by means of changes in photo signatures.

Vegetation in these arid to semi-arid environments appears to be …

Rodent Density And Species Composition In The Snake River Birds Of Prey Natural Area, Idaho, Jon R. Montan Jr.

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rodent densities were estimated in the major vegetation types of the Snake River Birds of Prey Natural Area in 1975 and 1976 by a combination of live-trapping and kill-trapping. Only deer mice (Peromyscus maniculatus) were numerous enough to permit reliable density estimates. Relative densities of other rodent species were indicated by kill-trap capture rates. Densities of deer mice correlated well (r = 0.99) with kill-trap capture rates. The use of kill-trapping in place of live-trapping in 1976 permitted extensive sampling throughout the 1930 km² study area. Differences were found among the major vegetation and land-use types in …

The Effect Of Four Mine Spoil Treatments On The Seedling Water Relations Of Two Plant Species, Lorraine K. Van Kekerix

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Surface mines in mountainous areas cause environmental deterioration at lower elevations in the watershed. The most successful long term solution to the downstream problem is revegetation. However, mine spoils are low in essential plant nutrients, have low water holding capacity, and are often acidic. These factors limit plant colonization. Plants must also be adapted to the environmental conditions of high elevations.

At the McLaren Mine, }1ontana, at 2800 m, it was observed that seedlings on revegetation plots were desiccated, indicating possible water deficits. Field and growth chamber studies were carried out to determine the effects of some spoil ameliorating treatments …

Biological Manipulation Of Blackbrush (Coleogyne Ramosissima Torr.) By Browsing With Goats, Frederick D. Provenza

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this study was to provide data on responses of Angora goats and blackbrush (Coleogyne ramosissima) to a biological manipulation program. Blackbrush utilization levels averaged 30, 16, and 6 percent (545, 367, and 147 kg per hectare) for the heavily, moderately, and lightly browsed pastures, respectively; removal rates of 77, 38, and 19 percent (1164, 582, and 291 kg per hectare) were projected.

Statistically significant differences in body weight loss (P=0.052) were noted for goats browsing in different replications. Goats lost an average of 14 and 19 percent of body weight in replications one and two, …

Sheep Behavior And Vulnerability To Coyote Predation, Ernest Albert Gluesing

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study examined the activity patterns and social relation ships between individuals in a large herd of domestic sheep (Ovis aries) in an effort to determine if behavioral characteristics predisposed certain individuals to coyote (Canis latrans) predation.

The research was conducted on the Cook Ranch near Florence, Montana, from March through September of 1975. Data were collected from a herd of 627 ewes and 1082 lambs, each individually identifiable. A random sample of 44 ewes and their 75 lambs were intensively studied over a 16-wk period to establish activity budgets and the relationships between sheep activity …