DPESTICIDESSWEwhat is a man-made ecosystem but you get the idea

Ecosystem Definition
The simplest definition of an ecosystem is that it is a community or group of living organisms that live in and interact with each other in a specific environment.
For instance, tropical forests are ecosystems made up of living beings such as trees, plants, animals, insects and micro-organisms that are in constant interaction between themselves and that are affected by other physical (sun, temperature) or chemical (oxygen or nutrients) components.

You should never redesign your experiment. try and see what in your experiment you made a mistake on or try and test your experimemt with somebody else. see if they get the right results.