<p> Wildfire and subsequent timber salvage harvests are forecasted to increase in the Alaska boreal forest, creating the need to evaluate the effectiveness of forest regeneration practices in light of these interacting disturbances. Silvicultural practices such as site preparation and assisted regeneration are carried out shortly after disturbance in order to ensure satisfactory reforestation. Thirty years after a stand-replacing wildfire and salvage, we sampled an operational-scale (26.7 ha) white spruce (<i>Picea glauca </i> Moench [Voss]) regeneration trial established in a productive upland forest. Regeneration treatments were applied in a split-split plot experimental design on two landform types (LF), four ground scarification treatments (GST) plus a non-scarified control, and five artificial white spruce regeneration treatments (WSRT) plus a natural seedfall control. We analyzed total biomass as well as stand density and basal area for all species, seeking to evaluate the persistence of regeneration silvicultural treatment effects 28 growing seasons after installation. Our results indicate GST had no significant effect on white spruce basal area or stem density. </p><p> However, compared to natural seedfall control plots, white spruce basal area was six times higher in planted seedling plots, and white spruce stem density (dbh ≥ 1.0 cm) was nearly three times greater in broadcast seeding plots. White spruce stem density from natural seedfall averaged 944 stems ha<sup>-1</sup>, but density was dependent on both topographic position and distance to wind-dispersed seed sources. Scarification nearly doubled Alaska birch (<i>Betula neoalaskana</i> Sarg.) stem density and basal area compared to non-scarified control plots. Planted white spruce plots supported 19% less birch basal area, except in the most intensive scarification treatments in which birch basal area did not differ. Although quaking aspen (<i>Populus tremuloides</i> Michx.) density and basal area were generally unaffected by the regeneration silvicultural practices in this study, intensive scarification reduced basal area by half on slope plots. These results confirm that regeneration silvicultural practices continue to influence stand development beyond the stem initiation stage, but practices that promote one species may reduce others.</p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:1599566 |
| Date | 05 November 2015 |
| Creators | Allaby, Andrew |
| Publisher | University of Alaska Fairbanks |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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