Comment by adolph

See also earthworms facilitating spread of invasives:

  Invasive species of earthworms from the suborder Lumbricina have been 
  expanding their range in North America. . . . Their introduction to North 
  America has had marked effects on the nutrient cycles and soil profiles in 
  temperate forests. . . . Some species of trees and other plants may be 
  incapable of surviving such changes in available nutrients. This change in 
  the plant diversity in turn affects other organisms and often leads to 
  increased invasions of other exotic species as well as overall forest 
  decline. They are considered one of the most invasive animals in the 
  Midwestern United States along with feral swine.

https://en.wikipedia.org/wiki/Invasive_earthworms_of_North_A...