Biology Commons^™

Gender Variation In Croton Californicus (Euphorbiaceae), James Lynwood Smith Ii

Loma Linda University Electronic Theses, Dissertations & Projects

Croton californicus Muell. Arg. (Euphorbiaceae) is a subshrub suspected of being dimorphic with phase choices. Gender variation in C. californicus was studied in natural populations of southern California for three years (1994-96) to observe patterns of gender !ability. Some sites exhibited significantly male-biased sex ratios, and these sites often had the greatest number of monoecious morphs, cosexual plants with unisexual flowers. Gender variation was quantified for cosexual plants by calculating the Estimated Floral Gender (EFG) which varied from 1.00 (female) to 0.00 (male). The distribution of the EFG was highly skewed towards maleness. Monoecious individuals were then categorized by …

The Effect Of Light Intensity On The Incorporation Of Calcium Into The Carbonate Skeleton In Bossiella Orbigniania, Carol D. Logan

Loma Linda University Electronic Theses, Dissertations & Projects

The effect of light intensity on the incorporation of calcium carbonate into the algal skeleton inBossiala orbigniana (Descaisne) Silva (1957) (Corallinaceae) was studied. Calcium-45 labeling of terminal segments under experimental laboratory conditions was used to estimate calcification rate. Plant sections were tested under each of six light intensities ranging between zero (darkness) and 1960 pW^-2cm Calcium incorporation was found to be enhanced in light treatments as compared with dark treatment. Light of intensities ranging from 285 pW cm^-2 to 1960 pW cm^-2gave enhancement effects which were not significantly different from each other. Three alternate …

A Comparative Analysis Of Plant Response Parameters : To The Los Angeles Aqueduct Systems In The Mojave Desert, California, Edwin F. Archbold

Loma Linda University Electronic Theses, Dissertations & Projects

A comparative study of the two Los Angeles aqueduct systems was appropriate and feasible because of the 57 year span between construction dates. Although, dealing with complex interactive relationships of a variety of parameters and some unmeasurable aspects, this project attempted to get a closer look at the impacts of man-made constructions in the Mojave Desert.

Land managers and ecologists are particularly interested in answering the questions, how did the Mojave Desert perennial vegetation respond to a utility construction, such as the Los Angeles aqueduct, and what is the intensity of damage to plant cover. The recovery rates for vegetation …

Plant Response To The Barstow To Las Vegas Motorcycle Race Of November, 1974, Candace E. Horsley

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of this study was to determine the disturbance spectrum of the perennial plant vegetation by the Barstow to Las Vegas motorcycle race. Transects were taken at the pit area, starting line, and at various locations along the race course. Measurements were also taken in undisturbed control sites near the test areas, the topographic and bio tic features being judged as equal. Methods employed consisted of aerial photograph analysis just before and after the race. On site ground measurements were taken four years after the 1974 motorocycle event. Measurements of diversity, stability, productivity, and community quality were calculated. The …

The Effect Of Carbon Dioxide Concentration On Calcification In The Red Coralline Alga Bossiella Orbigniana, A. Dwight Smith

Loma Linda University Electronic Theses, Dissertations & Projects

The relationship between various experimental concentrations of CO2 and calcification was studied by measuring Ca-45 incorporation into the crystalline matrix. Air containing CO2 at partial pressures (Pc02) of 0.04% to 5.5% was bubbled through synthetic sea water in incubation vessels. The resultant pH values ranged from 8.7 to 6.5. The relative concentrations ofCO2, HCO3 , and CO2— 3 were calculated from the measured ' pH—PCO2 combinations. Calcification was correlated positively with HCO expressed as percent of total carbon. Maximum calcification of about one—third above normal occurred between 0.1% and 1.0% P CCOO22 At 0.26% P calcification increased as increments of …

The Distribution Of Orcuttia Californica (Poaceae) In The Vernal Pools Of The Santa Rosa Plateau, Riverside County, California, Cluney M. Stagg

Loma Linda University Electronic Theses, Dissertations & Projects

Ecological studies were conducted on the rare annual grass Orcuttia californica (Vasey), an endemic to California, from April to September, 1976 in 11 vernal pools located on the Santa Rosa Plateau in Riverside County. To help determine why Orcutt grass occurs in only 6 of the 11 pools and more specifically why it only occurs in patches within a given pool, biweekly measurements of frequency, density and phenology were taken within each of a total of 28 circular plots (r = 10 meters) in 5 pools. This data was related to concurrent biweekly measurements of soil moisture, soil texture and …