Root development of acorn-origin oak seedlings in shelterwood stands on the Appalachian Plateau of northern Pennsylvania: 4-year results

Post-fire sprouting of oak seedlings in prescribe-burned shelterwood stands hinges on their root collar diameters exceeding 6.4 mm and root size depends on the type of partial cut and the time since harvest. To better understand this shelterwood stage/time/oak root size relationship, a study was begun in northern Pennsylvania in 2001. Acorns of black, chestnut, northern red, and white oak (Quercus velutina, Q. montana, Q. rubra, and Q. alba, respectively) were planted in mixed-oak stands treated with one of the cuts of a three-step shelterwood sequence (uncut, preparatory cut, first removal cut, and final cut) and the root development of the resultant seedlings was followed for 4 years. Root development of all four oak species was the least in the uncut treatment and changed little after the first year. Only northern red oak showed an increase in root size in the preparatory cut by the fourth year. All oak species had significantly larger roots in the first removal cut and final cut treatments by the fourth year with black and northern red oak having their most root development in the final cut and chestnut and white oak having their most root growth in the first removal cut. All species in the first removal cut and final cut treatments were nearing or had surpassed the 6.4 mm root collar diameter threshold by the third or fourth year indicating that at least 4 or 5 years should pass between the harvest and the prescribed fire.