Paper Birch Spacing Trials (UMN-CFC)

Combining analyses of measured short-term effects of early release with long-term growth simulations provided us with an opportunity to put our management strategies in a long-term perspective. Results clearly indicate that ELO and EHI treatments sacrificed short-term stand volume production. However, for most birch management scenarios, this is less important than ensuring that paper birch remains the dominant species and will not be threatened by fast-growing species in the near future. Although none of the tested release strategies had clear advantages over others in the short term, early release led to significantly improved birch growth and reduced birch mortality compared with controls. For mixed stands in which only a single treatment will be applied throughout the rotation, long-term projection results indicate that the EHI approach appears to provide adequate merchantable timber and may allow for increased paper birch sawtimber production, although perhaps at some risk of reduced stem quality. Long-term monitoring of growth and quality development will be necessary to evaluate whether and when stemwood production in EHI treatments surpasses that observed in the ELO treatment.