The Effectiveness of Cover Crops for Invasive Weed Control.

We completed three separate experiments to examine the effects of cover crops on invasive species abundance and on native species establishment.  In each experiment we added individual species of a cover crop, either at the same time or before the establishment of other species.  We always included one treatment where no cover crops were added.  This allowed us to examine the effects of cover crops.  We found that no species of cover crop was able to effectively control invasive species for multiple years.  Interestingly, there was a strong negative relationship between the biomass of cover crops and the biomass of invasive species during the first year in one experiment.  However, there was also a negative relationship between the biomass of cover crops and the biomass of other native species during the first year of this same experiment.  Annual and biennial cover crops had the greatest biomass at the beginning of the experiment, but when they died back in the second or third year, few native species were present and invasive species quickly filled in.  In conclusion, cover crops appear to compete equally with native species and invasive species, and prevention of invasive plant dominance may require the establishment of native species that can persist and compete strongly with invasive species.