You can't really construct it here, but you can always start thinking about making a food chain:
grass --> rabbit -->coyotes
then connect this to another food chain
The decay product is Radon-222 gas
Nothing really big... It floats because of density not surface tension.
But You can try and discover what will happen. :)
( P.S if you'll drop soapstone it will probably create nice waves... )
Ecosystems can be large and are made of biomes. Some examples of ecosystems are deserts and forests.
