HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by del Moral, R. Articles by Eckert, A. J. Search for Related Content PubMed Articles by del Moral, R. Articles by Eckert, A. J. Agricola Articles by del Moral, R. Articles by Eckert, A. J.

Colonization of volcanic deserts from productive patches¹

Department of Biology, Box 355325, University of Washington, Seattle, Washington 98195-5325 USA

Dense vegetation can augment landscape biodiversity, promote recovery of surrounding ecosystems, and facilitate colonization. However, dispersal limits affect vegetation structure early in succession to a degree that is not widely appreciated. We studied two contrasting densely vegetated habitats located on Mount St. Helens to explore their effects on surrounding vegetation. We sampled refugia and adjacent barrens and compared them to a study conducted 5 yr earlier. We sampled isolated wetlands and their surroundings. Species richness, total cover, cover of most dispersal types, the information statistic (H'), and the complement of Simpson's Index (D) were negatively correlated with distance from the refugia up to 32 m. Compared to 1997, the 2002 transects had higher cover, and adjacent samples were more similar to one another. Dominance had shifted from wind-dispersed species to more persistent species with less effective dispersal mechanisms. The pattern of these results demonstrated that refugia were a major, but indirect source of recruitment for many species. The influence of wetlands on surrounding vegetation recovery was even more spatially localized. This study demonstrates that dispersal from surviving and rapidly recovered vegetation has been overemphasized as a mechanism for vegetation recovery. The effects of dense vegetation did not extend beyond 32 m in our studies, and local effects appear to diminish over time.

Key Words: community assembly • dispersal • Mount St. Helens • primary succession • refugia • vegetation dynamics • volcano

This article has been cited by other articles:

				R. del Moral and I. L. Lacher Vegetation patterns 25 years after the eruption of Mount St. Helens, Washington, USA Am. J. Botany, December 1, 2005; 92(12): 1948 - 1956. [Abstract] [Full Text] [PDF]