Cedar trees and other woody plants can significantly reduce forage production for livestock (Figure 2. These trees compete for and steal precious water and soil nutrients away from our desirable pasture forage. By letting trees fester into grasslands, forage production can be exponentially reduced over time (Figure 3). As a result, stocking rate will be severely compromised over time.
In 2022 alone, South Dakota experienced a loss of 209,671 tons of forage (419,342,000 pounds) due to woody plant encroachment. Additionally, the amount of tree cover increased by 3% (South Dakota Rangeland Production Losses). Among many other wildlife and natural resource concerns, the more trees in a pasture, the less forage livestock will have to graze.
How much is that loss of forage worth to you?
Assume the loss of forage production was equal in value to current grass hay prices. Recent prices in the area estimate large round bales of grass hay around $100 – 125 per ton (USDA AMS Direct Hay Report – South Dakota). The loss of forage to trees in 2022 was worth nearly $21 million of large round grass hay bales.
209,671 tons of forage loss X $100 per ton = $20,967,100 of forage value lost
Alternatively, assume the loss of forage production reduced the value of the grazing season. One animal unit (AU) requires about 26 pounds of forage per day, or about 790 pounds per month (AUM). The average 1,200 pound cow with a three month old calf at her side is equivalent to 1.5 animal units and requires about 39 pounds of forage per day or 1,200 pounds per month (UNL Extension). The loss of forage to trees in 2022 could have supported 353,875 pairs for another month of grazing. Additionally, the loss of grazing days on pasture leads to an increase in the need for the livestock owner to feed and/or purchase more hay.
419,342,000 pounds of forage loss / 790 pounds per AUM = 530,812 AUMs lost
530,812 AUMs of forage loss / 1.5 AUM per pair = a month of grazing lost for 353,875 pairs
Lastly, assume the loss of forage production was equivalent to pasture rental values. The latest surveyed monthly rental rates in South Dakota ranged from $42 – 76 per pair or an average of about $55 statewide (South Dakota 2024 Land Survey). The loss of forage to trees in 2022 was worth nearly $19.5 million of potential rental revenue for landowners.
A month of grazing for 353,875 pairs X $55 rent per pair = $19,463,131 of rental rates lost
What do I do if I notice trees growing in my pasture?
Don’t wait. Removing trees when they are young has proven time and time again to be the most cost-effective course of treatment (Figure 4). Very young trees can sometimes be pulled straight from the ground, especially when the soil is soft and moist. Consider keeping a pair of loppers or a chainsaw in your rig with the rest of your tools. When you spend time repairing fences, checking water, or putting out salt and mineral, think about cutting some of those little trees along the way. Although care should be taken to cut the tree below the lowest branch to prevent resprouting.
Prescribed fire is an excellent tool for healthy grassland management. These controlled burns are brought forth with meticulous planning and team collaboration. Not only will prescribed fire kill seeds and trees in contaminated grasslands, but they are meant to mimic natural wildfire which stimulates native plant production. Prescribed fire is the best option for killing seeds before trees even have a chance sprout.
Seed dispersal and young trees can go unnoticed for several years before the problem even becomes apparent. Grasslands can go from contaminated to infested very quickly if nothing is done to combat the encroachment (Figure 4). Consequently, the impacts of woody encroachment can become overwhelming quickly. For that reason, collaboration and proactive management are key components in protecting pastures from woody encroachment. Connect with your neighbors, local groups, and state organizations for assistance. Some communities are even banding together to create prescribed burn associations that share resources and volunteers for controlling the spread of woody plants.
