This activity is carried out with the intention to inflict damage on logging tools such as chain saws, though logging companies allege that serious injury to loggers can result. Treespiking is illegal but was widely used by Earth First, a radical fringe of the environmental movement, in the 1980s. It is usually carried out by deep ecology groups.
Tree spiking was more recently described in Earth First! co-founder Dave Foreman's book Ecodefense as a way that environmental activists could thwart logging operations. It involves driving large metal nails (16d or larger) or spikes deep into trees scheduled to be logged, then warning the logging company or public officials that the area's trees had been spiked. The theory is that companies would then not log because the spikes could damage sawmill equipment. To avoid this, some sawmill operators check trees with metal detectors prior to milling, and in turn Foreman advocates the use of ceramic spikes which quickly become impossible to detect.
There has been far more rhetoric about tree spiking than actual cases of it being done in recent decades. Timber company public relations spokespersons have seized on it as a divisive issue to turn timber workers and dependent communities against environmental activists, particularly Earth First!
Recognizing this fact, Earth First! leader Judi Bari in 1990 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 non-violent protests against too-rapid corporate logging of the redwood forest.