Abstract
Decline of leafy spurge (Euphorbia esula) in the northern Great Plains of the US is generally viewed as a success story for biological control, but quality of the vegetation that survived the infestation is key to recovery of ecosystem function. In addition, effects of other invasive species, notably cool-season exotic grasses, must be taken into account. Objectives of this study were (1) to evaluate direction and significance of changes in biomass of native and exotic grasses, forbs, and leafy spurge and in plant species composition following control of leafy spurge by flea beetles and (2) to evaluate the relative effects of leafy spurge and exotic grasses on biomass of native grasses, biomass of forbs, and richness of native species. We monitored species composition (1998-2003 and 2008) and biomass (2000, 2002, 2003 and 2008) of these groups on spurge-infested and noninfested permanent plots at three sites with unbroken prairie sod in North Dakota, USA. We found little evidence, in terms of species richness or biomass of native grasses or forbs, that leafy spurge was being replaced by desirable native species, although desirable as well as weedy and exotic species were characteristic of 2008 vegetation at all three sites. Structural equation models revealed that leafy spurge had temporally intermittent negative effects on forb biomass and species richness, but no effects on native grasses. In contrast, exotic grass had consistently strong, negative effects on native grass biomass, as well as stronger negative effects than leafy spurge on native species richness. Although substantial native plant diversity remains at these sites, exotic grasses pose an important threat to these crucial building blocks of native prairie ecosystems.
Original language | English (US) |
---|---|
Pages (from-to) | 1901-1910 |
Number of pages | 10 |
Journal | Biological Conservation |
Volume | 143 |
Issue number | 8 |
DOIs | |
State | Published - Aug 2010 |
Bibliographical note
Funding Information:Funding for this study was provided by US Geological Survey Quick Response Program and Northern Prairie Wildlife Research Center. The US Fish and Wildlife Service, especially P. Scherr and K. Askerooth, provided important logistical support and cooperation. R. Finocchiaro, J.B. Grace, and three anonymous reviewers provided valuable comments on an earlier version of this manuscript. We thank the seasonal technicians whose hard work in the field made this study possible.
Keywords
- Agropyron repens
- Bromus inermis
- Euphorbia esula
- Mixed-grass prairie
- Poa pratensis
- Tallgrass prairie