What are the principal causes for the loss of ecosystems and biodiversity?

Are humans responsible for this?
How does this affect nature and the different animals in their habitats?
Does this problem affect humans too? Why?

Dear Guty. As we all know the humans are always searching for their own benefit. In this search they pass over anything that could stop them on making money. Humans are totally responsable for the loss of the ecosystem and biodiversity in their non-stop carrer on getting benefits. For example the deforestation is something that quit animals their habitat, and the opportunity to live in harmony with the world. And at last it really affect us, the humans. Seldom do I know a man who wants to affect the ecosystem, but as I tell you at the beginning the search of money and interest kill whatever good thinking humans have.