Persistence of suppression effects on peatland black spruce advance regeneration after overstory removal

The persistence of suppression effects on peatland black spruce (Picea mari ana (Mill.) BSP) advance regeneration following overstory removal was exami ned (i) by analyzing post-harvest growth patterns and (ii) by comparing obs erved post-harvest growth with predictions from an individual-tree growth m odel. Analysis of growth patterns revealed critical points (inflections or maxima) in annual basal area, diameter, and height growth series, and in sp ecific volume increment. Critical points occurred at different times (rangi ng from 1 to 29 years after harvest) for different variables and often occu rred earlier for trees with greater height at time of harvest. These critic al points do not necessarily coincide with the cessation of persisting supp ression, however, since post-harvest growth patterns also reflect current i nfluences on growth. The comparison of observed basal area and diameter gro wth with model predictions isolated persisting suppression effects. The eff ects of suppression on basal area and diameter growth decline linearly with time since harvest and become negligible 12 years after harvest. The persi stence of suppression effects on basal area and diameter growth is largely independent of the height of the tree at the time of harvest.