Earthworms and wilderness areas

I am planning to do some permaculture gardening in a native forest setting. I would be tempted to use earthworms for composting and castings but after reading "Suburban Safari" am concerned about what the available composting worms might do to the native flora and fauna in my forest area. I don't think sterilization is a practical solution. Do you know of a good source for the native earthworms and if so, do they do a good job with worm composting?
Thanks!

could you just gather native worms and put them in the area that you want to put them in..generally after a really hard rain in the early evening or after dark you can go out with a flashlight and find night crawlers that are just laying on the ground..also..you can stick a fork into the soil and wiggle it, and it will sometimes cause worms to come to the surface..

Thanks Brenda - I did not know about the fork trick. Basically I am concerned about worms from composting getting into the wild and decimating the forest floor flora. I've seen photos of what the red wigglers can do to kill the native forest wildflowers, etc. (and even the night crawlers, which are not native either)