Mountain biking a destructive activity?

From the Pittsburgh Tribune-Review:

I thought the media were supposed to present a complete picture, not a biased one.

In its Sept. 16 edition, the Tribune-Review, in a story titled “Pittsburgh becoming destination city for outdoors enthusiasts,” presents mountain biking as if it were a harmless activity.

Mountain biking is one of the most destructive activities ever allowed in natural areas and not something we should be promoting. It is especially inappropriate for city and local parks, which usually are small and have to serve a large population.

Mountain biking accelerates erosion, creates V-shaped ruts, kills small animals and plants on and next to the trail, drives wildlife and trail users out of the area and, worst of all, teaches kids that rough treatment of nature is OK. It’s not.

Quick google search turned up his website.

A little more digging found this site which spends time refuting the claims made by the author.