Pyric herbivory

Pyric herbivory is the term for the interactions of fire with grazing on a grassland.^[1] These interactions can promote biodiversity and function of grasslands.^[1] Fire will increase the amount of grazing in a certain area, as grazing herbivores prefer the nutritious forage available in recently burned areas.^[1][2] Since herbivores do not prefer areas that have not been recently burned, fuel will accumulate in unburned areas.^[2] This causes those areas to burn more easily in the future.^[2] These interactions between fire and grazing across space and time are referred to as positive and negative feedbacks.^[1] These interactions create heterogeneity across the landscape.^[1][2][3] Pyric herbivory is important to ecosystems that have evolved with fire and grazing, such as grasslands.^[4]

Pyric herbivory occurs because burning produces early successional plants that are more palatable and nutritious than late successional plants.^[1] Because of this, herbivores prefer the forage that grows in recently burned areas.^[1] Herbivores will graze more in the recently burned areas, causing leaf litter to build up in unburned areas.^[1] This makes the unburned areas more prone to fire in the future.^[1] Once fire occurs in a new area, herbivores will start grazing in that area.^[1][2] This creates shifting patterns of grazing and fire across the landscape.^[2]

The shifting patterns of heterogeneity that are created by pyric herbivory changes the number and type of plant species present in the area.^[2] This supports biodiversity of plants and wildlife in the area, restores and maintains ecosystem function, and aids in nutrient cycling.^[1][2][3] It especially increases the availability of nitrogen and phosphorus by converting litter into ash.^[3] A lack of disturbances such as fire and grazing can decrease biodiversity and soil function quality, as well as allow for woody encroachment.^[3][5]

There is a concern that agricultural livestock production will not be maintained when using conservation management strategies because of a need to lower stocking rates.^[6] Pyric herbivory is a strategy that allows landowners to maintain stocking rates without losing livestock productivity and also improve the health of the grassland.^[6]

There are social factors involved in whether a landowner chooses to implement pyric herbivory.^[5] These factors include previous experience of the landowner, the landowner's perception of woody encroachment on the land, proximity to neighbors, and risk orientation.^[5] Previous experience applying pyric herbivory will increase the landowner's likelihood to apply it as a management strategy.^[5]

• Controlled burn
• Socio-ecological system
• Livestock grazing comparison
• Rangeland management
• Grassland degradation
• Ecological restoration
• Conservation grazing