Grazing Response Index: How Healthy Are your Grazing Lands?
Agriculture and Agri-Food Canada
The Grazing Response Index (GRI) is a rangeland assessment tool developed in the United States and adapted to western Canadian rangeland conditions. The Index is a simple method to evaluate whether the current grazing management impacts have beneficial, neutral or harmful effects on plant health and establishes whether or not ranchers might need to adjust their grazing management techniques.
GRI uses three factors to evaluate grazing management impacts on plant health: frequency, intensity of grazing and opportunity for plant recovery. The combination of these factors measures plant responses to defoliation as positive, negative or neutral.
"This short term monitoring tool helps producers and land managers evaluate the effects of their current grazing management on plants and decide how to manage their rangeland the following year."– Kerry LaForge, Senior Range and Forage Biologist at Agriculture and Agri-Food Canada
How the GRI is Calculated
- Grazing frequency refers to the number of times forage plants are defoliated during a grazing/growing period. This helps land managers estimate how many times plants can be grazed, and takes into consideration slower growth times of the year, such as in late summer heat and drought.
- Grazing intensity is a measure of how much leaf material has been removed or grazed, that is, the percent utilized. The more leaf area left behind, the more quickly plants can regrow or recover.
- Opportunity for recovery is the amount of time plants have to grow prior to grazing or for regrowth after grazing. The opportunity for plants to grow or regrow is dependent on soil moisture, air temperature and leaf area. Therefore, it is also important to consider the quality of the recovery period, as it is a strong indicator of the long-term health and vigour of pasture growth.
Find Your GRI
The GRI tool provides a basis to assess the potential impacts of grazing. In combination with other comprehensive rangeland assessment tools, GRI can help ranchers make range management decisions to maintain or improve plant health, structure and vigour.
- Agriculture and Agri-Food Canada (AAFC) helps bring Canadian ranchers a new method of assessing the long-term health of their grazing lands.
- This short term monitoring tool helps producers and land managers evaluate the effects of their current grazing management.
- GRI uses three factors to evaluate grazing management impacts on plant health: frequency, intensity of grazing and opportunity for plant recovery.
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