Savanna
In North America, the word savanna is also used to describe the tall grass prairies that have scattered trees, typically oaks.  This is a temperate climate (colder than the tropics).  It is called an oak savanna since the oak tree is the main tree.  At least half of the view of the sky must be open.  If there are more trees, then it is called a grove or a woodland.  If there are fewer trees, it is a prairie. If there are many kinds of trees and brush and very little grass, then it is a forest.