How can introduced shrubs create unnatural scrublands in former grasslands?

Introduced shrubs can create unnatural scrublands in former grasslands when an alien, vigorous shrub species is introduced into a region where woody plants are otherwise rare or absent. Once established, these species can multiply and dominate the landscape, effectively converting the area into dense, unnatural scrubland.12

This process is exemplified by the introduction of the giant sensitive plant (Mimosa pigra) from Mexico into the seasonally flooded, grass-dominated areas of northern Australia, where it has formed extensive thickets. Similarly, the African shrub Acacia nilotica is currently invading the Mitchell grasslands in northeastern Australia, demonstrating how the arrival of non-native woody plants can fundamentally alter ecosystems that were previously dominated by grasses.2