frith vs ground cover

frith

noun
  • Land with mostly undergrowth and few trees; also, land in between forests or woods; pastureland which is not in use. 

  • Brushwood or undergrowth, sometimes in the form of a hedge. 

  • A forest or wood; woodland generally. 

  • A hedge, especially one made from brushwood which has been wattled; also, a movable frame made from wattled branches, a hurdle. 

ground cover

noun
  • Something, particularly plants, which overlays an area of land. May refer to plants specifically grown to prevent erosion of an area. 

How often have the words frith and ground cover occurred in a corpus of books? (source: Google Ngram Viewer )