Abstract

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 microrelief of each plot, area and order of desiccation of each pool. Frequency and density show no correlation to soil moisture, soil texture, and area. There is, however, a positive correlation between occurrence of the study species and the (1) order in which the pools become desiccated; and (2) average depth of plot. This is probably related to the germination requirement of the seeds having to be submerged for a minimum amount of time. Also under different soil moisture conditions there seem to be differences in the time sequences of the phenological events.

LLU Discipline

Biology

Department

Biology

School

Graduate School

First Advisor

Earl W. Lathrop

Second Advisor

Raymond E. Ryckman

Third Advisor

Donald D. Rafuse

Degree Name

Master of Arts (MA)

Degree Level

M.A.

Year Degree Awarded

1977

Date (Title Page)

5-1977

Language

English

Library of Congress/MESH Subject Headings

Grasses -- California -- Riverside County; Grasses -- Research

Type

Thesis

Page Count

vi; 76

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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