Staff writer Louis Sahagun's article (April 12) on the dangers of driving and the frequent fatal accidents by riders of all-terrain vehicles (the three-wheel variety) didn't say it all. The use and misuse of this type of vehicle is a major contributor to damaging and destroying any fragile terrain, especially that of our desert areas. All-terrain vehicles are supposed only to be used in designated off-road areas. Instead, ever so many are driven off-road indiscriminately. People don't realize that a two-wheel motorcycle racing across the open desert churns up and damages or destroys about an acre of fragile and slow-growing terrain per mile of driving. Just think about what the three-wheeler, with those nubby wide tires is doing to the terrain!