I used to chop roots when removing shrubs/trees (in fact I had a special "rough" axe and a mattock with an adze blade that I used). These days I just cut them with my 18V Ryobi reciprocating saw (using a carbide blade so it doesn't get blunt too quickly from running in the dirt)
babola: "Enjoy your tools and don't be afraid to air your opinion and feelings here, but do it in courteous and respectable way toward others, of course."