Simplify the following text for a Grade 12 native English-speaking person.
Original: More complex arguments in ecosystem valuation regard nature 's services and the assignment of values in a service economy to all that nature does `` for humans '' .
Simplified: More complex arguments in ecosystem valuation regard environmental ethics and deep ecology . Economists and some ecologists concentrate upon nature 's services and the assignment of values in a service economy to all that Nature does `` for humans '' .