How are niche, community and ecosystem related?

They are all related because they all involve habitat. Its the place where the organism lives. Its a group of organisms in a specific place. A niche is the facts describing what the organisms need to survive, ecosystem is a community of interacting organisms and a community is the is the place where the organisms are.

Niche is the role of each living thing in the ecosystem which it lives, the ecosystem is an environment which living organisms live and work in, every organism plus their niche, role in the ecosystem, form a community. A community is like a family where everyone depend on each other through relationships.