Answer:
independent ecosystem
Explanation:
A tree can be called an independent ecosystem.
That’s because the tree can sustain a life on its own, and can also provide support to other forms of organisms.
Birds can make nest in the tree. Creepers and crawlers can take shade in its trunk and branches.
The tree can have bee hives and ants etc on it. It may produce fruits etc for animals to eat.
And in this way it can act as an independent ecosystem without help of any other living organism.
