Managing forests infested by spruce beetles in south-central Alaska: Effects on nitrogen availability, understory biomass, and spruce regeneration

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• 作者：Lilly F. Goodman and Bruce A. Hungate
• 关键词：Bluejoint ; Calamagrostis canadensis ; Dendroctonus rufipennis ; Forest management ; Nitrogen availability ; Picea glauca ; Resin capsules ; Spruce beetle ; White spruce
• 刊名：Forest Ecology and Management
• 出版年：2006
• 出版时间：1 June 2006
• 年：2006
• 卷：227
• 期：3
• 页码：267-274
• 全文大小：423 K

文摘

In Alaska, an outbreak of spruce beetles (Dendroctonus rufipennis) recently infested over one million hectares of spruce (Picea spp.) forest. As a result, land management agencies have applied different treatments to infested forests to minimize fire hazard and economic loss and facilitate forest regeneration. In this study we investigated the effects of high-intensity burning, whole-tree harvest, whole-tree harvest with nitrogen (N) fertilization, and conventional harvest of beetle-killed stands 4 years after treatment, as well as clear-cut salvage harvest 6 years after treatment. We measured available soil ammonium and nitrate and estimated N loss from leaching using in situ cation and anion resin exchange capsules. We also assessed spruce regeneration and responses of understory plant species. Availability and losses of N did not differ among any of the management treatments. Even a substantial application of N fertilizer had no effect on N availability. Spruce regeneration significantly increased after high-intensity prescribed burning, with the number of seedlings averaging 8.9 m⁻² in burn plots, as compared to 0.1 m⁻² in plots that did not receive treatment. Biomass of the pervasive grass bluejoint (Calamagrostis canadensis) was significantly reduced by burning, with burn plots having 9.5 % of the C. canadensis biomass of plots that did not receive treatment. N fertilization doubled C. canadensis biomass, suggesting that N fertilization without accompanying measures to control C. canadensis is the least viable method for promoting rapid spruce regeneration.