Crop-Tree Release Increases Growth of Black Birch (Betula lenta L.) in Southern New England

Abstract

Abstract Black birch (Betula lenta L.) has become an increasingly important component of northeastern forests in recent decades. In 1996ߝ97, plots were established in five stands to examine diameter and volume growth response of black birch to crop-tree release. The stands were from 20 to 99 years old, and mean crop-tree diameters ranged from 4.8 to 13.8 in. Growth of crop trees was monitored for 8 years. Over the 8-year period, diameter and volume growth of completely released poles (4.6ߝ10.5 in. in diameter) were twice that of unreleased poles. Increased growth was noted the 1st year after release and showed no indication of decreasing after 8 years. Release did not affect diameter growth of small sawtimber crop trees (10.6ߝ13.5 in. in diameter) until the 3rd year after release. However, after 8 years, diameter and volume growth were nearly 40% greater than for unreleased trees. Release had negligible effect on diameter and volume growth of medium sawtimber crop trees (more than 13.5 in. in diameter). If crop-tree management was initiated in young stands of black birch poles (mean diameter of upper canopy trees was 4.5 in.), then the time required to grow those trees to diameters of 13.5 in. could be reduced by nearly 50%.