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Protecting understory white spruce during removal of overstory aspen will ensure the utilization and release of advanced spruce growth, which will result in a shortened rotation, reduction of reforestation cost, and eventually an increase of timber production per unit of land.  While the strip-cut understory protection harvest is being increasingly adopted across Alberta, there is a lack of information on how residual spruce in removal strips respond to release and how successful aspen regeneration occurs on the extraction trails, which leaves uncertainty on the development of mixedwood stands treated through strip cut harvest.

The Strip Cut Understory Protection Trial (SCUP) project aims to fill the information gap required for growth and yield projection of aspen-dominated mixedwood stands treated with strip cut understory protection harvest.

The objectives are to provide:  

  1. A measurement protocol to collect statistically valid data for describing the Block1-level stand performance following Strip Cut Understory Protection harvesting; 
  2. A protocol that is sufficiently flexible in order to be used by numerous companies, and to account for operational differences in the application of Strip Cut Understory Protection systems; 
  3. Re-measured data to quantitatively describe the post-harvest development of stands after Strip Cut Understory Protection harvest treatments; 
  4. Information required for growth model development and/or model calibration, with the potential for future use in process-based modelling; and
  5. A monitoring protocol that is acceptable to the Alberta government, for use in monitoring and yield curve validation.

A total of 18 understory protection PSP installations were established: 5 in 2005 and 13 in 2007. Plots are being measured on a five-year cycle and data is being made available for development of the Mixedwood Growth Model (MGM).