An area that's mostly wild and covered with small trees or shrubs is called a scrub. This can be a place like a forest but not as thick.
When we talk about a scrub in everyday life, it usually means a bit of land that's not very big or formal, often near the ocean or on an island. Think of a scrub as being similar to a forest but smaller and with more open spaces between the trees. Some people might use scrub to describe a specific type of tree or bush, like a scrub oak or a desert scrub plant. In these cases, they're pointing out that it's not a big, fancy tree but something more low-key and wild-looking.
How common is "scrub"?
Word scrub is considered uncommon in modern English. It appears most frequently in fiction texts and less often in other writings.
Definitions
noun
One who labors hard and lives meanly; a mean fellow.
One who is incompetent or unable to complete easy tasks.
Example: What a scrub! Instead of washing the dishes she put the used food on her face!
A thicket or jungle, often specified by the name of the prevailing plant
Example: oak scrub
(stock breeding) One of the common livestock of a region of no particular breed or not of pure breed, especially when inferior in size, etc. Often used to refer to male animals unsuited for breeding.
Vegetation of inferior quality, though sometimes thick and impenetrable, growing in poor soil or in sand; also, brush.
One not on the first team of players; a substitute.