Encroachment of woody plants has occurred in many of the world's grasslands within the past 3 centuries. Mechanisms underlying these physiognomic shifts have not been adequately described. My objectives were to elucidate the roles of interference, herbivory, acorn maturation date and timing of precipitation on emergence and survival of Emory oak (Quercus emoryi Torr.) at lower treeline; and to evaluate how different frequencies of monitoring influence the results of demographic studies with woody plants. Seedling emergence was negatively affected by delays in precipitation and decreased soil moisture content. Seedling survival was negatively affected by overstory and understory interference and vertebrate herbivory. Most seedling mortality was attributed to desiccation. Woody plants should be monitored at least monthly to evaluate emergence and survival after one year. These results indicate that abiotic constraints are the primary factors structuring southwestern oak woodlands and savannas.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/278609 |
| Date | January 1997 |
| Creators | Germaine, Heather Lynn, 1972- |
| Contributors | McPherson, Guy R. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Thesis-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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