[Jeff Higgins]

Originally Posted by RWebb

they no longer spike trees

AND no one has ever been injured from one

old wives' tale

I didn't even have to look that hard.

http://en.wikipedia.org/wiki/Tree_spiking

In 1987, California mill worker George Alexander was seriously injured when the bandsaw he was operating was shattered by a tree spike.
Tree spiking was declared a federal felony in the United States in 1988. (18 U.S. Code 1864).
In 1990, Earth First! leader Judi Bari led activists in Northern California and Southern Oregon to renounce tree-spiking as a tactic on the eve of Redwood Summer, a 1990 campaign of nonviolent protests against logging of the redwood forest.[5]

http://www.wisegeek.com/what-is-tree-spiking.htm

As tree spiking became more widespread in the late 1980s, especially in Northern California and Southern Oregon, some activists became concerned about the practice. Several documented injuries indicated that tree spiking had the potential to be deadly, and many environmentalists were concerned that tree spiking was giving their movement a bad name. As a result, many groups condemned the practice, arguing that there were safe and more effective ways to put a stop to logging. Within Earth First!, members were split on the issue, and continue to be to this day.

http://www.nytimes.com/1990/11/04/magazine/if-a-tree-falls-in-the-forest-they-hear-it.html?pagewanted=all

Many Earth Firsters make a moral distinction between their actions and terrorist ones because they target only inanimate objects. They say they draw the line at causing harm to people. Yet the potential for injury does exist, as demonstrated by a 1987 tree spiking that seriously injured a California timber worker when his saw shattered. The episode was never officially linked to Earth First, which advocates that spikers mark their trees with a spray-painted "S." But not every spiker complies. The very need to promote a warning proves the possibility of injury.

There are plenty more for anyone interested enough to look.