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Individual study: Biocontrol of invasive leafy spurge Euphorbia esula by flea beetles Apthona allows exotic grasses to become dominant in northern Great Plains prairies, North Dakota, USA

Published source details

Larson D.L. & Larson J.L. (2010) Control of one invasive plant species allows exotic grasses to become dominant in northern Great Plains grasslands. Biological Conservation, 143, 1901-1910

Summary

Leafy spurge Euphorbia esula (native to Europe) has becoming invasive over large areas of prairie and pasture in the northern Great Plains of USA. Successful control (via release of flea beetles Apthona)has been achieved in many areas but quality of surviving native vegetation is considered key to prairie recovery. A study in North Dakota was undertaken to evaluate floristic changes (composition and biomass) of native and non-native grasses, forbs, and leafy spurge following control by flea beetles, and the relative effects of leafy spurge and non-native grasses on native species recovery.

Monitoring of plant composition (1998-2003 and 2008) and biomass measurements (2000, 2002, 2003 and 2008) on spurge-infested and non-infested permanent plots was undertaken at three prairie sites.

Desirable native grasses and forbs (as assessed by species richness and biomass) showed little evidence of replacing leafy spurge, although desirable, weedy and non-native species were present at all sites in 2008.

Leafy spurge had intermittent negative effects on forb biomass and species richness, but did not impact native grasses. Non-native grasses (e.g. quackgrass Agropyron repens, smooth brome Bromus inermis and smooth meadow-grass Poa pratensis) had consistent strong, negative effects on native grass biomass, with stronger negative effects than leafy spurge on native species richness.
 
Substantial native plant diversity remains at the sites, but exotic grasses pose a major threat to re-establishment of native prairie plant communities.