Respacing of Sitka spruce natural regeneration under continuous cover forestry

An area of respaced Sitka spruce regeneration beneath a Sitka spruce canopy

The respacing experiment was set-up to establish the effects on growth and survival different respacing treatments would have on Sitka spruce natural regeneration. Two one hectare plots were established, with each of these being split further into 0.25 ha plots where each of the four respacing treatments would occur. During 2006 the following respacing treatments were carried out:

  • Control (no respacing)
  • Seedlings respaced to 1.6 m (to retain 4000 trees ha-1)
  • Seedlings respaced to 2.0 m (to retain 2500 trees ha-1)
  • Seedlings respaced to 3.2 m (to retain 1000 trees ha-1)
  • Seedlings respaced to 5.0 m (in which good quality individuals were selected at 5 m spacing and regeneration within a 2 m wide radius of these trees was cleared).

In all respacing treatments tree selection was based on both position and quality of the stem.

Plots have been sampled in each of the respacing treatments and have been sampled annually since 2009. Within each of these plots height, diameter, leader and lateral length were recorded. In addition whether a tree is missing or has died has been assessed.

Results from this study will help inform the management of natural regeneration occurring in coninuous cover forestry (CCF) areas.