Crop Tree Release Improves Competitiveness of Northern Red Oak Growing in Association with Black Cherry

Abstract

Abstract In 1993, a crop tree study was established in a pole-sized stand consisting of black cherry (Prunus serotina Ehrh.) and northern red oak (Quercus rubra L.). Black cherry was the predominant species in the stand and appeared to be on the verge of virtually eliminating northern red oak based on its greater height growth potential. To assess crop tree management for maintaining the competitiveness of oak in this situation, the stand was compartmentalized into treated and untreated areas and crop trees were selected. In the treated areas, crop trees received a three- or four-sided crown-touching release. Individual tree characteristics were measured following the growing seasons of 1993 and 10 years later. Crop tree release resulted in slowing the height growth of codominant black cherry, but not northern red oak. Ten-year mean height growth of northern red oak exceeded that of released black cherry, but not that of unreleased black cherry crop trees. Crown expansion and diameter at breast height (dbh) growth also increased as a result of crop tree release for both species, but black cherry clear stem development was suppressed. Based on increment core analysis, dbh growth of released northern red oak crop trees in 2003 was about twice that of unreleased northern red oak, although black cherry treatment related differences in radial growth were no longer present. Ten years after crop tree release, northern red oak crown class distribution improved and black cherry crown class distribution was unchanged. These results suggest crop tree management will improve northern red oak competitiveness in pole-sized stands when growing in association with black cherry and, perhaps, other fast growing species.