turning an ornamental bed into small food forest

hi,
I have an area in my garden that was planted with heather and shrubs when we moved in 10 years ago, we haven't touched it so far.
I want to 'replace' this stuff with food cropping plants in a fruit tree guild (probably 2-3 trees). I have some perennial plants ready that would be happy in this guild.
Do I grub up everything in the ornamental bed and start from bare earth? that doesn't seem right, but what should I do instead? slash it all down and use for mulch?
I want to put apple and pear trees in, with rhubarb X2, cardoon X3, jerusalem artichoke (loads), lovage- I have all these plants on the property, they are well established already but poorly sited.

any suggestions on a dramatic reworking versus gentle guiding ?

Dave, do you have a complete list of everything in the bed? There might be some of those plants with other value than ornamental? How about a picture.

I hope my images show up here.
not sure what any of this stuff is- obviously there are a few nettles, there is a conifer tree, and a big evergreen bush. I am surprised to see some ground cover in there under the bushes- didn't think anything would survive with such limited light.

okay, well, the first post here: http://djsc18.tumblr.com/ shows some pics of the plants in the bed.