Does Leafy spurge (Euphorbia esula) Leave a Soil-Borne Legacy as Populations Decline?

Although the invasive rangeland weed leafy spurge has begun to decline in the northern Great Plains, recruitment of native plants, especially forbs, is often quite limited in sites formerly occupied by the plant. Without replacement by desirable native plants, these sites are vulnerable to subsequent invasion by other weedy species or reinvasion by leafy spurge.

The goal of this research is to identify the reasons why native recruitment is limited in soils that previously supported leafy spurge populations. Ultimately, our aim is to develop sustainable restoration techniques for belowground processes as well as aboveground vegetation characteristics.

Preliminary data indicate substantial differences in microbial function between rhizosphere samples from native plants in increasing versus declining spurge stands. In addition, bacterial species composition varied between spurge rhizosphere samples from increasing and declining spurge populations.

Experimental restoration plots will be established to test the ability of various species to survive in and re-condition soils previously occupied by leafy spurge.

	Contact: Diane L. Larson USGS, Northern Prairie Wildlife Research Center 100 Ecology Building, 1987 Upper Buford Circle St. Paul, MN 55108 dlarson@usgs.gov