| Invading plants may cause biochemical changes to native plants by altering resource availability, thereby also changing the forage quality of native plants for native browsers. I measured plant growth, carbon and nitrogen content, and tannin and total phenolic production, which generally lower forage quality, in the boreal native Salix alaxensis under differing scenarios of invasion by nitrogen-fixing Melilotus alba. Additionally, I evaluated whether different populations of M. alba in Alaska suspected of having different introduction histories varied in competitive ability. I found that in this common garden experiment shading and soil nitrogen levels consistent with those found in M. alba populations did not significantly negatively affect S. alaxensis forage quality. Increase in soil nitrogen was associated with overall greater available protein levels in the willows. Last, I found no differences in competitive abilities among populations from different regions around the state, indicating all populations should be treated as equally invasive. |
