It is called a forest.
Forest
Thicket
calumpo
A small group of trees is called a "Grove".
I would call that a "stand of trees"
grove
yes but they are very small trees so the call them dwarf trees.
There are many synonyms for a collection of trees:groveorchardcopsestandforestbushhedgeclumpwindbreak
A flotilla
Banana Grass
controlled experiment
a bundel of bamboo
you call them a fleet but if they are wardhips you call them armada
A small group of stars that appear to be close together are often known a cluster. Technically its an asterism.
You would probably call this area a stand or thicket.