In forestry, high grading is a selective type of timber harvesting that removes the highest grade of timber (i.e. the most merchantable stems ) in an area of forest. The stunted, slow growing or poorly formed trees that are left as residuals will, if ecological conditions permit, reseed the space that has been created. Over time the practise of high grading can therefore give rise to forest stands containing stems of less value in terms of timber quality.
The opposite of this practice is low grading, where the lower quality trees are periodically harvested, making the genetic stock faster growing and of better timber quality.
High grading is a practice of selectively harvesting fish so that only the best quality fish are brought ashore. The practice is popular in situations under individual fishing quotas where only a limited number of fish are allowed to be harvested. Following the letter, but not the spirit of the law, fish are caught, and if not considered optimal, thrown back into the ocean. The practice of high grading allows anglers to get high prices for their limited catch but is environmentally destructive because many of the fish returned to the water die.
In mining, high grading refers to mining out the portions of the orebody that has the highest grade of material to be mined, however it may also refer to the concealment and theft of valuable gold or silver ore by miners for personal profit. Common in the United States in the late 19th century and early 20th century, high graders would usually conceal gold ore in a pocket or lunch pail, or within the body, and later attempt to fence it on the black market.
As mining companies became more aware of the growing problem, they built changing stations where they forced the miners to shower after their shift in the mines, making it easier to foil attempts at theft.
“HIGH GRADING AT TONOPAH.” The arrest of four men for high grading took place at Tonopah last Friday morning as the men were coming off shift at the McNamara mine. The men arrested are William Turner, vice president of the Tonopah miners' union; Tom Conifrey, Tom Cunningham and Patrick Flanigan. They were caught with the rich ore concealed upon their persons, and is it said that nearly a wagonload of ore was recovered from the residences of the high graders. These men have been suspected for a long time, and Friday morning the entire shift was held up and searched. All were lodged in the county jail, and two of them have since given bail. It is announced that they will be prosecuted to the full extent of the law. -Rhyolite Herald, October 28, 1908
- History of highgrading in California (mining)