Regeneration responses of oak-dominated stands to thinning and clearcutting in northwestern Pennsylvania

Regenerating mature oak stands on better sites is difficult on the Allegheny Plateau because of abundant advance regeneration of faster growing competitors. We have observed that oak stands on the Allegheny National Forest (ANF) in northwestern Pennsylvania almost always regenerate to cherry-maple rather than to oak-hickory stands. Such conversion greatly concerns land managers and the general public. We surveyed 30 stands, varying in size from 8 to 42 acres, in a 786 acre compartment on the Sheffield Ranger District to document typical responses of oak-hickory stands on good sites to partial and complete overstory removal. These stands were 90 to 110 years-old when cut. Five stands were clearcuts that originated from previously uncut stands; 18 stands had been partially cut; and 7 stands remained uncut. The five clearcuts were 4 years old (1 stand), 7 years-old (1), and 15 years old (3) when examined. The 7 year old stand was fertilized 2 years after clearcutting. The 18 thinned stands were treated 6 years before we examined them. Trees to be cut were individually marked by ANF staff and commercially harvested. Advance reproduction in thinned stands varied from 0% to 75% of regeneration plots stocked with preferred species. Black cherry was more abundant in the advance reproduction than in the overstory. Advance reproduction of sapling size was present in 15 stands, occurring in up to 40% of plots in a stand. Most saplings were black cherry or red maple. Black cherry was the most numerous species in the clearcut stands and the only species consistently in the dominant position of the new age class. Isolated patches of dominant and co-dominant oak saplings were in the main canopy of the new age class on dry microsites and along skid trails. Oak seedlings were present in the new age class, but all were less than 1 ft tall. The unfertilized clearcut stands grew at essentially the same rate, or considerably faster than previously sampled cherry-maple stands. Response to fertilizer was of a magnitude similar to that in previously sampled cherry-maple stands.