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Individual Highlight

Sprouts as Rapid Bioassays of Browse Impact

Photo of Maple stump with browsed sprouts outside fence and unbrowsed, tall sprouts within fence. Alejandro A. Royo, U.S. Department of Agriculture Forest Service.Maple stump with browsed sprouts outside fence and unbrowsed, tall sprouts within fence. Alejandro A. Royo, U.S. Department of Agriculture Forest Service.Snapshot : Effective browse pressure indicators are necessary to adaptively manage forest landscapes with resident deer. Hardwood tree stump sprouts are a reliable and easily measured phytoindicator in disturbed forests. Deer browsing reduced sprout height by 39 percent when averaged across tree species. Browse impacts on sprout height at local (2.5 acre) scales is a valuable indicator of estimated deer densities at larger (1 square mile) scale.

Principal Investigators(s) :
Royo, Alejandro A. 
Research Location : Northern hardwood forests of Northwestern Pennsylvania
Research Station : Northern Research Station (NRS)
Year : 2016
Highlight ID : 985

Summary

Effective browse pressure indicators are necessary to adaptively manage forest landscapes with deer. In a large-scale experiment distributed across a 2,500-square-mile region, Forest Service scientists at the agency’s Northern Research Station found deer browsing on hardwood tree stump sprouts varied among species and reliably tracked browse pressure throughout a range of deer densities. Specifically, maples (Acer rubrum and Acer saccharum) were preferred over beech (Fagus grandifolia) and black cherry (Prunus serotina). Under ambient browsing, black cherry was 60 to 100 percent taller than other species. When protected from browsing, maples doubled in size, relative to browsed individuals, and were as tall as black cherry. Browse impact on sprout height measured at local (2.5 acre) scales was correlated with deer densities estimated at larger (1 square mile) scales and suggest sprout surveys can track deer browse impact throughout larger areas. Our results demonstrate that sprouts, particularly maple sprouts, offer an abundant, easily measured, and reliable indicator of browse pressure. Moreover, negative browsing impacts on sprouts appeared before impacts were detected on seedlings. Thus, these results suggest sprouts can warn of imminent browse risk to regeneration, allowing managers to take actions to mitigate or avert losses to the regenerating seedling cohort.

Forest Service Partners

External Partners

 
  • University of Georgia

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