Regarding the garden area;
You could try adding some 'tufts' or small balls of 'underbrush' in neat little rows, that would do the trick!
Tufts would probably stand up to the rigours of gaming a little better, though.
How about an axe embedded in the tree trunk by the log pile?
If you want to add a little more depth to the otherwise flat areas of the base, dolls house plants and flowers work pretty well, just make sure that you use the smaller varieties.