Can We Control Leafy Spurge? Adaptive Management and the Recovery of Native Vegetation

摘要

Land managers in North America have battled leafy spurge (Euphorbia esuki), an invasive-exotic plant introduced from Eurasia, for more than half a century. We chronicle a ten-year adaptive management project by The Nature Conservancy to control leafy spurge on a prairie preserve in the Prairie Coteau region of South Oakota. We documented the effectiveness of three biological control agents- domestic goats (Capra hircus), domestic sheep (Ovis arics), and flea beetles (Apthona czwali-nac, A. hicertosa, and A. nigriscutis)-in the control of this noxious plant. In addition, we measured the response of the native plant community to control treatments and to competition with leafy spurge in untreated areas. Vertebrate grazers failed to reduce the cover of leafy spurge after five years, although goats prevented its expansion. In contrast, flea beetles dramatically reduced the cover and expansion of leafy spurge. Species richness declined in untreated plots during the first five years of the study in comparison with actively managed plots. The decline in native species richness in unmanaged plots demonstrated the consequences of leaving invasive species populations unchecked, even for relatively short periods of time.