Calculating Carrying Capacity

Rangelands May 11, 2011|Print

Carrying capacity is the number of grazing animals a piece of land can support long term without causing harm to rangeland resources (vegetation, soils, and water). The characteristics of the land, vegetation, and soil determine the carrying capacity, not the land manager. Proper carrying capacity attempts to balance between long-term forage supply and forage consumption by all grazing animals, both livestock and wildlife. Determining carrying capacity is an important goal of any rangeland inventory or monitoring program and forms the basis of stocking rate decisions. Furthermore, an assessment of carrying capacity can provide information on potential economic returns from ranch developments and forms one basis of ranch value on the real estate market.

How do you determine carrying capacity?

The simplest and most reliable way to determine carrying capacity is to obtain past stocking rates and grazing management information for a piece of land and then assess the ecological status or condition of the rangeland. If the condition is good or improving, the current stocking rates are below carrying capacity. If the condition of the rangeland is declining, carrying capacity has been exceeded, and grazing management practices or stocking rate may have to be adjusted.

What if there are no historical stocking rate data available?

One can estimate carrying capacity for a parcel of land in several other ways, even without historical stocking rate information. The first way is to measure annual forage production on the land and calculate an estimate of carrying capacity.

This method is useful but is based on a series of estimates for annual forage supply and animal demand. Continued monitoring of range condition and adjustments may be necessary to determine a final carrying capacity. Your local Cooperative Extension Service or Natural Resources Conservation Service office can assist you in this process.

Another way to estimate carrying capacity is to compare the land to similar rangeland with a successful history of setting stocking rates. Find out the carrying capacity estimates of the area and use those as a guideline to begin the process of determining an appropriate carrying capacity for your particular piece of land.

Trial and error is an inherent part of estimating carrying capacity. Additionally, carrying capacity is complicated by the fact that both forage production and animal intake are dynamic factors that vary with ecological site, topography, time of sampling, and plant species composition. The diets of grazing animals also vary according to animal nutritive requirements and the unique dietary preferences of species, breeds, and individuals. Therefore, carrying capacity estimates should be treated as an initial starting point for the management unit that will almost certainly be revised with continued monitoring and current environmental conditions.

Adapted from: Sanders, K., Determining Carrying Capacity

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