Overgrazing is a phenomenon that occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or overpopulations of native or non-native wild animals. Overgrazing reduces the usefulness, productivity, and biodiversity of the land and is one cause of desertification and erosion. It is also seen as a cause of the spread of invasive species of non-native plants and of weeds. Overgrazing can lead to soil erosion, making it much harder to grow anything on the land, and can cause a food shortage for both grazing animals and human beings.

One indication of overgrazing is that the animals run short of pasture. In some areas of the United States under continuous grazing, overgrazed pastures are predominated by short-grass species and will be less than 2 to 3 inches tall in the grazed areas. In other parts of the world, overgrazed pasture is usually taller than sustainably grazed pasture, with grass heights usually over 1 meter and dominated by unpleasant species. In such cases of overgrazing, the soil might be visible between the plants, enabling erosion to occur.

Overgrazing is used as an example in the economic concept now known as the Tragedy of the Commons, which was devised in a 1968 paper by Garrett Hardin. The concept refers to the unregulated use of land regarded as a common resource.

Responsible farming is the best way to prevent overgrazing. It’s important for farmers to manage where their animals graze, and others can help by supporting farmers in their efforts to stop overgrazing. Buying food from farms with responsible practices is the best way to do so.