Evaluating site preparation techniques for wetland prairie restoration

The method of site preparation is among the most important factors for determining the ultimate success of a restoration project. In collaboration with the West Eugene Wetland Partnership, we established a large, replicated study to examine the effectiveness of site preparation techniques for wetland prairie restoration. The objective of this research is to examine common wet prairie restoration techniques in a replicated design to assess (1) the response of plant community structure, diversity, and productivity, (2) seasonal measurements of functional soil ecosystem attributes related to carbon and nutrient cycling, (3) changes in physical and chemical attributes of the soil, and (4) the extent to which plant and soil responses are interactive and mutually dependent. This experiment was implemented on a 4.5-ha site (previously in Lolium multiflorum production) west of Eugene, Oregon in 2004. Site preparation techniques were chosen to (1) kill the existing vegetation (tilling, spring herbicide application) and (2) decrease viable seeds in the seed bank (solarization, thermal weed control, fall herbicide application). These techniques were implemented in 10 different combinations with 5 replicates of each treatment. Additionally, three high-quality wetland reference sites and five plots from the adjacent Lolium field were monitored for comparison. None of the treatments resulted in a significant change of belowground responses after two years, but aboveground plant communities were distinctly different from one another, with solarization and a fall herbicide application being the most effective at decreasing exotic cover and richness.