Knowing how to estimate loss of livestock production due to redcedar encroachment can be a major benefit for cattlemen.
By: Carol Blocksome, Range Specialist, K-State Research and Extension
Eastern redcedar encroachment is an increasing problem in rangelands in the eastern two-thirds of Kansas. The Kansas Forest Service estimates that there was a 23,000 percent increase in redcedar volume in Kansas between 1965 and 2005. Increased redcedar cover in rangelands results in undesirable conversion of rangeland to forest, negatively impacting prairie wildlife habitat and decreasing the amount of available forage for livestock.
Controlling redcedar, and thereby increasing forage production, can have a positive economic impact for producers by allowing them to stock more livestock in the same paddock. A redcedar calculator has been developed that allows a producer to roughly determine the amount of forage lost to red-cedar encroachment and the related reduction in carrying capacity of a paddock. The calculator was based on measurements taken in the tallgrass prairie and has not been evaluated for mid-grass or short-grass rangelands. The calculator can be found on the "Education" page of the ksfire.org web site (under the "Reasons for Burning" subhead). You will need to enable macros to use the calculator.
To use the calculator, the percent canopy cover of the paddock, by size class, must be determined, along with an overall estimate of the total number of redcedar plants in the paddock. In addition, the estimated biomass production, either from measurement or from soil survey information, along with the number of acres, must be input into the calculator. Producers frequently work with the Natural Resources Conservation Service (NRCS) to gather the input information.
The calculator output estimates the amount and percent of biomass (forage) and the Animal Unit Months (AUMs) (based on a 6-month grazing season) that are lost due to redcedar encroachment for the analyzed paddock. The calculator also estimates the additional number of cow-calf pairs (increased stocking rate) that could be supported if redcedar were eliminated.
For example, if 50% of the trees are 10-15 ft. in diameter, and 20% of the trees are 15-20 ft. in diameter, with a total of 80 trees and an estimated production of 2500 lbs./acre, you will have reduced your carrying capacity by 1.5 cow/calf pair in a 160 acre pasture.
Because redcedar invasion occurs gradually over a period of years, it can be difficult to perceive the accumulated loss of forage due to this invasion. Very small trees (<2 ft.tall) have little impact on grass productivity, with grass frequently growing right up to the tree stem. However, as the tree increases in diameter, the forage loss becomes more pronounced. As the amount of forage decreases, grazing intensity needs to be adjusted downward (fewer animals, shorter grazing period, or both). Failure to decrease stocking rate as tree cover increases leads to overgrazing. Overgrazed rangelands often suffer from an increase in undesirable plants (from both a livestock and ecological viewpoint), decrease in ecosystem functioning (including less water infiltration, thus reducing forage growth even more), increased soil compaction, increased soil erosion by wind and water, and an absence of wildlife habitat. In addition, livestock gains are reduced on a per-head basis.
Control of redcedar is primarily carried out with burning for small trees (less than 3 feet in height) and by mechanical means for areas with either larger trees, dense stands without a grass understory, or where fire poses a safety hazard. By allowing producers to calculate forage losses, the costs of redcedar control can be considered in conjunction with the potential for positive financial returns due to increased livestock production.
Complacency and procrastination concerning redcedar invasion can lead to loss of income not only through decreased stocking rates, but by also increasing the eventual cost of tree removal.