Cutting a trees root?

[Blinkz]

Hey folks,

I'm the middle of redoing my garden. I've got to the point where I need to decide on where my beds/lawn are going to be before I rotavate and get the turf in.

The issue I'm having is that there is a rather large tree root on the surface at 90 degrees to where I want to have a bed. If I leave it then the root will be sticking up through the lawn and look crap!

How much of an issue is it to cut off this offending root? Will it kill the tree?

Thanks!

 

[Blinkz]

Not sure what tree it is! Here's some pics:

Tree:

The root thats causing the issue:

Its not the root running down the left hand side of the picture, its the one coming out to the right into the garden.

 

[Blinkz]

Thanks for the tips guys. Sadly it would take a huge bed to go around the root, and it would be quite a bit higher then the lawn to fully cover it. Doh! Running out of options