• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 248
  • 56
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 1657
  • 436
  • 293
  • 242
  • 218
  • 192
  • 177
  • 147
  • 143
  • 138
  • 112
  • 98
  • 98
  • 96
  • 95
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
541

A reconnaissance of upper cretaceous plants from the Blackhawk formation in Central Utah, and their paleoecological significance

Parker, Lee Ross 26 April 1968 (has links)
A well-preserved flora has been collected from the Upper Cretaceous Blackhawk Formation near Salina, Utah. This formation is part of the Mesaverde Group and consists mostly of deltaic sediments deposited along the western margin of a Cretaceous sea. The Blackhawk Flora is comprised of the following species: Eguisetum sp., Osmunda hollickii, Allantodiopsis erosa, Saccoloma gardneri, Araucaria longifolia, Ginkgo laramiensis, Protophyllocladus polymorphus, Sequoia affinis, Geonomites imperialis, Sabalites montanus, Dryophyllum subfalcatum, Juglans similis, Cinnamomum sezannense, Magnolia ampifolia, Menispermum dauricumoides, Ficus glasconea, Ficus planicostata, Ficus puryearensis var. elongata, Myrtophyllum torreyi, Nymphaeites dawsonii, Dalbergia (?) prewilcoxiana, Salix lesquereuxii, and Trapa paulula. Two independent studies were used to determine the climatic conditions that existed when the Blackhawk Flora was living. The first study was an analysis of the fossil leaf features compared with features of modern leaves whose climatic requirements are known. It was determined that the fossil leaves of the woody dicotyledonous species exhibit a high percentage of entire margins, pinnate venation, simple organization, thick texture, large size, and dripping points. These are characters possessed by modern floras living in warm, humid climates. The second study was of the distribution of the nearest living relatives of the fossil plants. This investigation indicated that the modern correlatives of the Blackhawk Flora prefers climates that are warm-temperate to subtropical. Both paleoclimatic studies indicate that the Blackhawk Flora lived in a humid, warm-temperate to subtropical climate.
542

Field observations and laboratory studies on growth and tillering in seedlings of oryzopsis hymenoides as affected by selected environmental factors of the sand dunes of Lynndyl, Utah

Smigelski, Leopold B. 01 August 1968 (has links)
Seedlings of Indian rice grass Oryzopsis hvmenoides (Roem. & Shult.) Ricker. were studied to determine the effect of soil moisture, photoperiod, depth of burial of germinated grains, temperature, and the rate of soil accumulation on seedling growth and tillering. The study was performed in two phases: Field observations and laboratory studies. Field observations were made on a system of sand dunes located northwest of Lynndyl, Utah. General observations were made from January, 1966 to May, 1968.
543

Algal response to a thermal effluent : study of a power station on the Provo River, Utah, USA

Squires, Lorin E. 01 December 1977 (has links)
The effect of a thermal effluent on the attached algae of the Provo River, Utah, USA, was studied from 1975 to 1977. Data for macroscopic and microscopic algae were collected and analyzed. Diatoms, Cladophora glomerata, and Hydrurus foetidus dominated the flora. The thermal effluent significantly affected the algal flora in a section of river 100 to 135 meters long immediately below the discharge point. Cladophora growth was increased and Hydrurus was absent in this area. In addition, diatom production was often higher and diversity lower than in the rest of the river. Community structure was unique from all other adjacent areas. Small temperature increases which occurred as effluent and river waters mixed farther downstream were apparently not as important to the algal flora as other environmental factors.
544

The succession of vegetation on a southern Utah sand dune

Castle, Elias S. 01 August 1954 (has links)
The sand dunes lying ten miles northwest of Kanab in Kane County, Utah, support a sparse plant cover with four species dominating the vegetation: Psoralea stenostachys, Sophora stenophylla, Oryzopsis hymenoides, and Wyethia scabra var. attenuata. Of these Psoralea and Wyethia are endemic to the dunes or to a limited area which includes the dunes. The pineer species gain a start in the valleys between dunes and occupy the area only until sand covers them or until sand is blown away from their roots. Stabilization of the soils is not permanently in the interdune valleys and the dunes continue to wander. The low fertility of the soils, the low moisture content, the extremes of temperature, light, and other environmental factors limits the number of individual plants which can occupy the dunes. The region will continue to have actively moving dunes until major climatic changes occur permittimg a denser plant cover which would tend to stabilize the sands.
545

Vegetational changes in a mountain brush community of Utah during eighteen years

Eastmond, Robert J. 01 August 1968 (has links)
This vegetational analysis is concerned with changes which have cocurred since 1949 in a mountain brush community within an exclosure in the central Wasatch Mountains. The exclosure, established in 1949, is located in Pole Canyon on lower Provo Canyon. Two major studies have been conducted previously, but it has been nine years since the last intensive work was done. Several major changes occurring during the eighteen year period are evident and are described.
546

A study of conifer invasion into meadows surrounding small lakes and ponds in the Trial Lake region of the western Uinta Mountains

Firmage, David Harvey 01 August 1969 (has links)
The object of this study was to determine whether or not Lodgepole pine is successfully invading meadows near ponds in the western Uinta Mountains as a preliminary step to the invasion of the Spruce-Fir climax forest. Line transects were established at three sites near Trial Lake extending from forest to wet meadow. Along these transects the soil was studied to determine percent organic matter, pH, depth to mineral soil, and texture. Also the depth of the water table was measured and the topography plotted. The age and size of the trees along the transect was determined, and the extent of some root systems was noted. Conifers found growing in the dry meadow were stunted and no conifers were found growing on peat deposits over 17 inches. The water table was found within about 8 inches of the surface and the soil conditions suggested poor aeration. The combination of peat and high water level accounted for the stunting of the trees. The trees were apparently unable to convert the dry meadow to forest and thus, the climax for hydrarch succession in this area is a meadow vegetation of grasses and sedges instead of the conifer forest.
547

An ecological study of Timpanogos creek from Aspen Grove to Wildwood

Harris, Marion L. 01 January 1926 (has links)
Ecology may be oonsidered as one of the vital parts of botany, since there are two ultimate facts in this science; namely, the plant and its habitat . The habitat is made up of the physical factors that control function. At Timpanogos there are so many different habitats, that the chief problem is not that of finding a problem to study, but rather that of selecting one from the many. The purpose of this paper is to point out some of the interesting features that are found in a study of Timpanogos Creek from Aspen Grove to Wildwood.
548

The distribution of plant types in the Escalante Desert of Utah with relation to soil conditions

Lambert, Carlyle B. 17 May 1940 (has links)
This problem was a study of plant species in the Escalante Desert, Utah, in relation to soil conditions. The plants were surveyed by the transect-plot method. The plants and soils were analyzed by percentage-frequency techniques. There is no measurable correlation between soil series and the dominant plants which occur on the soils. There is no correlation between soil types and the plants that are dominant on the soil types. There is a definite correlation between textural classes of the soil and the plants that are dominant on these classes.
549

An ecological study of an exclosure in the mountain brush vegetation of the Wasatch Mountains, Utah

Nixon, Elray S. 01 August 1961 (has links)
This is a comparative study of the vegetation and soils of an exclosure in the mountain brush vegetation of the Wasatch Mountains, Utah. The exclosure was fenced and initially analyzed during the summers of 1949-1950. The study area is located in Pole Canyon in the Uinta National Forest, a few miles northeast of Provo, Utah. The dominant woody species of the vegetation in the exclosure are big toothed maple (Acer grandidentatum) and Gambel oak (Quercus gambelii). After settlement of the area in and around Provo, Pole Canyon became overgrazed by livestock. Since 1949 the area has been protected from grazing. The purpose of this study was to analyze the vegetative and environmental relationships in the exclosure and to determine any changes occurring since the initial study by comparison with the results of the preliminary study.
550

Correlations between plant species diversity and flower characteristics in the Wasatch Mountains of Utah and Idaho

Ostler, William Kent 01 April 1976 (has links)
An analysis of the relative abundance of the prevalent species in 25 major plant communities of the Wasatch Mountains demonstrates that variation in species diversity is significantly correlated with many floral characteristics. Wind pollinated flowers decrease in abundance while animal pollinated flowers increase along the diversity gradient. Both relationships are highly significant statistically. Color diversity and species diversity are significantly and positively correlated in open communities but are not correlated in forest communities. The percent sum frequency of yellow and pink-magenta flowers decreased with increasing species diversity while blue and whitish flowers increased. Also, zygomorphic flowers and flowers in which access to the nectar supply is restricted by morphological barriers are positively correlated with species diversity. It is shown that wind pollinated flowers and entomophilous open flowers are significantly more abundant than animal pollinated flowers whose nectaries are morphologically restricted, Theoretical explanations are offered for these relationships.

Page generated in 0.0341 seconds