The stability of lower treeline in the southwestern United States has been the subject of recent debate. An understanding of seed predation and dispersal is required to evaluate these predictions. Experimental plots were established along the oak woodland/semi-desert grassland boundary to investigate seed predation and dispersal of emory oak, a common lower treeline species. An aviary experiment investigated acorn selection by grey-breasted jays, important emory oak seed dispersers. I found sufficient acorn dispersal for emory oak recruitment in adjacent grassland, and that seed predation does not limit oak recruitment in adjacent grasslands; in fact, acorns dispersed into adjacent grasslands are more likely to escape predation. I determined that grey-breasted jays select and cache acorns in a manner favorable to oak recruitment. Taken collectively, these studies and other research into emory oak life history stages illustrate mechanisms by which rapid downslope shifts in lower treeline can occur.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/278530 |
| Date | January 1995 |
| Creators | Hubbard, John Andrew, 1969- |
| 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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