Examining the utility of advance regeneration for reforestation and timber production in unsalvaged stands killed by the mountain pine beetle: Controlling factors and management implications

Abstract

In unsalvaged stands killed by the mountain pine beetle, the release and growth of shade-tolerant advance regeneration may provide an important reforestation pathway. Stands developing from advance regeneration may restock quickly and provide short- to mid-term harvest opportunities, but the variability in release and growth responses among these stands will create numerous management challenges. This paper reviews and synthesizes relevant scientific literature to suggest some important differences between reforestation from advance regeneration following mountain pine beetle (MPB) attack and conventional reforestation (i.e., planting or natural reforestation following “normal” disturbance events) in regards to stand dynamics and growth. Particular attention is given to the primary traits of advance regeneration that may determine its successional and growth trends following mpb attack, including species composition, abundance and spatial distribution, developmental characteristics, and overall health. Effective management of advance regeneration following MPB attack will require a better understanding of the stand-level conditions and processes that control its growth. As well, management tools such as stocking standards that are suited to managing even-aged forests may need to be re-examined to address the unique conditions of unsalvaged MPB stands.

Considerations for Rehabilitating Naturally Disturbed Stands: Part 2. Stand Level Treatments and Hydrological Equivalent Clearcut Area

“…The contribution of advanced regeneration increases as understorey trees release and grow over 20+ years. Nevertheless, uncertainty about how well the understorey will release after beetle attack and how fast growth will be with the patchy distribution of these trees (Griesbauer and Green 2006) is a source of uncertainty in projecting ECA.…”

Regeneration and Growth Following Mountain Pine Beetle Attack: A Synthesis of Knowledge

“…The greatest abundance of secondary stand structure (existing seedlings, saplings, poles, and residual trees) following MPB attack probably is found in stands where pine was the seral species (Griesbauer and Green 2006); however, the successional patterns and processes of stand development from new seedling establishment to seral lodgepole pine remain largely unknown, as most previous investigations were based on regeneration, either planted or natural seeding, immediately following a large-scale stand disturbance (e.g., logging or forest fires) (Messier et al 1999). This gap could be diminished by studying natural succession to a climax stand structure.…”

“…may be found in the advanced regeneration cohort in uneven-aged stands on edaphically limiting sites (Stuart et al 1989;Williams et al 1999;Kneeshaw and Burton 1997;Hawkes et al 2004;Daintith et al 2005). The MPB disturbance enhanced the release of shade-tolerant species, resulting in the rapid conversion of stands from lodgepole pine to shade-tolerant conifers (Griesbauer and Green 2006). This contributes to the conversion of an even-aged stand to an uneven-aged stand (Roe and Amman 1970).…”

“…Moreover, poorly planned and executed large-scale salvage operations have significant negative effects on several forest values, including hydrological regimes at various scales (Foster et al 1997;Lindenmayer et al 2004). Therefore, unsalvaged stands are not only important for ecological restoration, but they also provide a unique opportunity to establish permanent sample plots (Griesbauer and Green 2006), which can subsequently reshape our knowledge about the regeneration and stand dynamics under complex conditions following the MPB outbreak.…”