|Jordan, N - UNIVERSITY OF MINNESOTA|
|Svenson, E - UNIVERSITY OF MINNESOTA|
Submitted to: Ecological Society of America Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 22, 2003
Publication Date: August 6, 2003
Citation: BLUMENTHAL, D.M., JORDAN, N.R., SVENSON, E.L. TALLGRASS PRAIRIE RESTORATION CONTROLS WEEDS. ECOLOGICAL SOCIETY OF AMERICA PROCEEDINGS. 2003. Technical Abstract: Weed control in non-cropland often precludes management for biological diversity. It may be possible, however, to use native late-successional plant communities to exclude weeds, thereby managing simultaneously for diversity and weed control. We studied a limited form of this generalization, considering the invasibility of a particular native community, tallgrass prairie, by a class of invader, early-successional weeds. We measured invasion of extant and added weeds within randomized, 6-year-old plots of restored prairie and unrestored, old field vegetation. This experimental approach enabled us to separate the effects of late successional vegetation per se from factors that commonly covary with late successional vegetation, such as propagule pressure and time since disturbance. Restoration reduced extant weed biomass by 94%, extant weed stem number by 76%, and stem numbers of four individual extant weed species, relative to no restoration. Similarly, restoration reduced added weed biomass by 85% and reduced biomass of 4 individual added weed species, each by greater than 92%. To examine potential mechanisms underlying weed responses, we treated subplots with burning (to reduce establishment limitation), and N addition (to reduce competition). The role of establishment limitation in reducing weed invasion is suggested by increased litter mass and reduced weed density with restoration, and by stronger weed responses to burning in restored than unrestored plots. The role of competition in reducing weed invasion is suggested by increased biomass of extant vegetation, decreased light levels and decreased weed size with restoration.