Master's Theses

Date of Award

Fall 1985

Degree Name

Master of Science (MS)

Department

Biology

Advisor

G. K. Hulett

Abstract

A four-year study from 1980 through 1983 assessed the population dynamics, flowering dynamics, and biomass allocation in a population of Yucca glauca. The number of plants that flowered during the four-year period ranged from 57 in 1983 to 282 in 1982, with several plants flowering in each of three consecutive years. The plants were grouped into twelve size classes and it was found that most flowering occurred in the size classes 5-7. The number of stalks, buds, flowers, and pods produced by a plant depended on the size of the plant and probably was related to stored energy reserves. From bud initiation to mature pod, there was a 91.9% average mortality rate; most mortality occurred between the flower stage and the first pod census (taken shortly after the flowers wilted). The number of flowers maturing to fruits averaged 4.5 to 11.2%. The total reproductive effort for the population, using calculations of biomass allocations to different morphological structures, was estimated to be 16%. If belowground biomass were included in the estimate, then reproductive effort deceased to 8.0%. Average reproductive effort per individual for Yucca glauca was 44.6% (aboveground biomass only) and 22.3% (aboveground + belowground biomass). Because Yucca glauca usually flowers every 2 or 3 years, the amount of energy used for sexual reproduction over the life span of the plant is further reduced.

Rights

Copyright 1985 Colleen M. Hampton

Comments

Notice: This material may be protected by copyright law (Title 17 U.S. Code).

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