Tree spiking is a form of sabotage which involves hammering a metal rod or other material (commonly ceramic) into a tree trunk in order to discourage logging. A metal saw blade hitting an embedded spike could break or shatter, making it uneconomic to fell those trees. Spikes could possibly injure or kill loggers. It is often referred to by critics as a form of Eco-terrorism, because its tactics are to intentionally harm, or coerce log workers by fear of physical harm, from sawing at the tree.
It is believed that tree spiking originated in timber logging labor disputes in the Pacific Northwest of the United States in the late 1800s. It came to prominence as a contentious tactic within unconventional environmentalist circles during the 1980s, after it was advocated by Earth First! co-founder Dave Foreman in his book Ecodefense.
Some tree spikers tend to mark the spiked trees, ostensibly to deter the harvesting of the spiked trees. This practice along with directly informing milling companies is a key practice when tree spiking, since the objective is to stop the cutting of the tree, not damaging the chainsaw. Some sawmill operators check trees with metal detectors prior to milling. Also, chainsaws are equipped with chain guards that are designed to prevent a broken chain from injuring the operator. Due to the intentional informing of sawmills to the presence of tree spikes and logging company safety practices the likelihood of human injury is considered negligible by activists.
While Foreman claimed that injury to humans was an unlikely consequence of tree-spiking if the spiking was made known to authorities or logging companies, the tactic was condemned not only by the companies themselves, but by labor interests and, eventually, other members of Earth First.
Pat O'Dea, while he was the mayor for the Buller District, suggested in 2000 that Native Forest Action (NFA) had spiked trees during a direct action campaign against native forest logging on the West Coast.  This was denied by NFA spokesperson Dean Bagient-Mercer.  In 1998 Kevin Smith from Forest and Bird had said that tree spiking was proposed by some individuals involved in the NFA campaign. 
In 1987, California mill worker George Alexander was seriously injured when the bandsaw he was operating was shattered by a tree spike.
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.
Tree spiking in fictionEdit
Severed (2005 film) Anti-logging activists sabotage a tree by spiking it, breaking the blade on a logger’s chainsaw and cutting him. The genetically enhanced tree sap mixes with the logger’s blood, starting a chain reaction of zombie mayhem.
Darkness Falls (The X-Files) Two environmentalist "monkey wrenchers" are accused of spiking trees in a Washington state forest.
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