Patch cutting in temperate mixedwood stands: What happens in the between-patch matrix?

Abstract

Over the last two decades, patch cutting systems have been applied in Eastern Canada to regenerate uneven-aged yellow birch (Betula alleghaniensis Britton)-conifer stands. Yet, we still know very little about how the trees located in the between-patch matrix respond to treatments. This study compares growth, recruitment, and tree mortality of yellow birch, red maple (Acer rubrum L.), balsam fir (Abies balsamea [L.] Mill.), and red spruce (Picea rubens Sarg.) in three 50% patch cutting treatments with 20-, 30-, and 40-m diameter circular gaps combined with 33% single-tree cutting in the matrix between patches and an uncut control. After 10 years, the positive effects of cutting treatments on recruitment and growth were nullified by mortality, resulting in nonsignificant changes in stand net merchantable basal area. The mortality rate modeled at the tree level was highest for trees with larger diameters, defects, and high crown ratios. Trees with small diameters and those located along the border of harvest gaps had the largest increments in basal area. This study questions the use of patch cutting in mixed uneven-aged stands comprising an important component of short-lived balsam fir. Silvicultural systems utilizing nonsystematic placement of variably sized gaps may prove more beneficial for managing wood production and complexity in yellow birch-conifer stands.