Dispersal, not Understory Light Competition, Limits Restoration of Iowa Woodland Understory Herbs

Mabry McMullen, Catherine
Mabry, Catherine M.
Mottl, Larissa M.
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© 2010 Society for Ecological Restoration International
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Natural Resource Ecology and Management
Plant community restoration may be limited by the inability of target species to disperse to a restoration site (i.e. dispersal limitation) or by the failure of species to establish once seeds do arrive (i.e. establishment limitation). Seed additions attempt to overcome dispersal limitations; however, seed additions may fail due to establishment limitations resulting from competition with pre-existing vegetation. We tested whether dispersal and/or competition with the pre-existing understory limited restoration of 22 native deciduous woodland herbs in Iowa, United States. We employed an experiment that varied seed mix composition to contain either high densities of forbs or graminoids, coupled with clipping of pre-existing understory vegetation to reduce competition for light during establishment. We found strong support for dispersal limitations, as seed additions increased understory richness by 4 – 8 species/m2 . This was due to the addition of species from the seed mix, not modification to the naturally occurring plant community, which suggests the existence of an open (unsaturated) plant community. Most species in our seed mix established at high rates and there was no effect of seed mix (high vs. low density of graminoid vs. forb seeds) on the richness or persistence of species added by seed. Light competition with the pre-existing understory vegetation did not limit establishment. We recommend simple seed sowing to restore the majority of species in our study; 19/22 species readily established. Our results support the use of less expensive seed mixes containing high density of gramoids, relative to forbs.
This is the peer reviewed version of the following article: Brudvig, Lars A., Catherine M. Mabry, and Larissa M. Mottl. "Dispersal, not understory light competition, limits restoration of Iowa woodland understory herbs." Restoration Ecology 19, no. 101 (2011): 24-31, which has been published in final form at DOI:10.1111/j.1526-100X.2010.00675.x. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
deciduous forest, dispersal limitation, establishment limitation, oak/hickory woodland, seed addition, species diversity, understory control