Woody plant encroachment
Woody plant encroachment (also called woody encroachment, bush encroachment, shrub encroachment, shrubification, woody plant proliferation, or bush thickening) is a natural phenomenon characterised by the area expansion and density increase of woody plants, bushes and shrubs, at the expense of the herbaceous layer, grasses and forbs. It refers to the expansion of native plants and not the spread of alien invasive species.