How could you explain this statement "An ecosystem is constantly changing ,yet it remains the same."

Answer 1

That means that the system is not stagnant; i.e., all of the parts of the system are changing from one form to another but the overall percentages don't change with time. Let me give you an example in chemistry (since I'm a chemist). It's similar to equilibrium. In a chemical reaction of

A + B <==> C + D when the system reaches equilibrium, A and B are reacting to form C and D but C and D are reacting to form A and B. As a result, the overall concentrations of A, B, C, and D don't change with time although they are constantly changing from one to another.