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Individual Highlight

How not to kill mountain laurel

Photo of Photo 1.  A typical mountain laurel thicket in a mixed-oak forest in central Pennsylvania.  Such thickets prevent oak seedlings from becoming established and developing into competitive reproduction.  Note the 8-foot range pole in the center of the photo to appreciate the density and height of the shrubs. 
Photo 2.  A fall prescribed fire being conducted by Pennsylvania Bureau of Forestry personnel in a mountain laurel thicket that had been cut approximately 2 years earlier.  Initially, this combination of treatments showed the most promise of controlling mountain laurel, but after 5 years the shrubs had sprouted and the thicket was quickly reforming. 
Photo 1. A typical mountain laurel thicket in a mixed-oak forest in central Pennsylvania. Such thickets prevent oak seedlings from becoming established and developing into competitive reproduction. Note the 8-foot range pole in the center of the photo to appreciate the density and height of the shrubs. Photo 2. A fall prescribed fire being conducted by Pennsylvania Bureau of Forestry personnel in a mountain laurel thicket that had been cut approximately 2 years earlier. Initially, this combination of treatments showed the most promise of controlling mountain laurel, but after 5 years the shrubs had sprouted and the thicket was quickly reforming. Snapshot : Sometimes failure can be as important as success when it comes to developing appropriate silvicultural treatments for controlling interfering understory vegetation. A Forest Service scientist succeeded in establishing that seven common treatments do not work when it comes to controlling mountain laurel, a pervasive problem in eastern forests.

Principal Investigators(s) :
Brose, Patrick 
Research Location : Several Pennsylvania State Forests
Research Station : Northern Research Station (NRS)
Year : 2017
Highlight ID : 1258

Summary

Generally, interfering understory vegetation is not a major hindrance to regenerating mixed-oak forests on less productive sites unless mountain laurel dominates the understory. When this evergreen shrub becomes so plentiful that is forms thickets, then the oak regeneration process stops. Forest managers need to know which of several silvicultural treatments is the most efficient means of controlling mountain laurel so oak seedlings can be established and developed into competitive reproduction. To address this problem, a Forest Service scientist began a comparative study of seven common treatments for controlling mountain laurel: cutting, burning, cutting followed by burning, crushing, two herbicide application methods, and no management (control). Five years after applying the treatments, the mountain laurel had sprouted, and the thickets were quickly reforming in all treatments. Furthermore, several treatments caused black birch, blackgum, and sassafras to regenerate en masse. Relative to doing nothing, three treatments actually made the situation worse for oak seedlings and three only slightly improved conditions, but those benefits appear to be fading rapidly and will be gone in a few more years. Clearly, controlling mountain laurel thickets will require different approaches than what the scientist tried in this project.

Forest Service Partners

External Partners

 
  • Pennsylvania Bureau of Forestry

Strategic
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