Effectiveness and Cost of Shrub Removal Methods in Degraded Woodlands Being Converted to Silvopasture

Transforming degraded woodlands to silvopasture is of interest in the Midwestern USA as it increases profitability of farms and benefits animal health. Invasive shrubs within woodlands, however, are a major obstacle to silvopasture establishment. Research was undertaken to evaluate the effectiveness, cost and resulting herbaceous canopy light interception of common brush-control methods when used alone or integrated over a two-year timeframe. Five treatments were established in a randomized complete block design. In the first year, treatments were either forestry mowed (mow) or rotationally grazed by goats (goats) at a stocking density of 5700 to 6000 kg per hectare. In the second year, mow and goat treatments were either grazed by goats again or shrubs were treated with a herbicide (herb). These were compared to a non-treated control. Costs of each treatment were calculated based on labor, equipment/supplies, and contracts. Vegetation composition and herbaceous canopy light interception were evaluated the summer after treatments were implemented. Forestry mowing followed by herbicide was the least expensive treatment at $1833/ha, while goats were 72% higher. Light interception by the herbaceous canopy was not reduced by goats, but mowing followed by goats increased light interception such that it was greater than repeated goat grazing (p\u3c0.05). While shrubs were initially impacted by treatments, resprouting resulted in no differences in abundance compared with non-treated controls. Grass abundance was similar in control plots and treatments (p\u3e0.05). Forb abundance remained similar in control and goat-grazed treatments but increased in mowed areas. Costs and effectiveness of multi-year treatments will continue to be evaluated through 2024