I'm originally from Vancouver and I'm also a trailbuilder. Years ago people were just cutting trails and creating stunts that were very unsafe. When the local land managers started removing stunts and closing some trails the mountainbike community (mostly trailbuilders) got together and started the NSMBA www.nsmba.com to organize the builders. They now have a big voice with the local governments and land managers. I would suggest contacting them, talk to Sharon or Lee, they are an incredible wealth of knowledge and may have some ideas.

The trails on the shore don't have the same issues as you can't ride up them but I hate to hear that someone is cutting down live trees. In all of the trailbuilding that I've done I've never cut live trees.

I now live in Colorado and most of the land here is national forest or protected land or private. People still build trails here but if you get caught building you can go to jail. I think that's a bit harsh but it stops the illegal cutting of live trees.

I would suggest building a network of like minded cyclists and win the battle with information not action. Many mountain bikers just don't know about forests and the effect that trails have on erosion. If we didn't have trees and grasses on the mountains, holding all the soil there, we would just have big hunks of rock.