Experimental Design:
FERP treatments were adapted from the German “Femelschlag” system based on a 1% natural disturbance frequency common to this region (Figure 1). Three treatments are replicated three times in a randomized complete block design (Table 1). Basic ecological data (i.e., tree species composition and distribution, stand growth, herbaceous community, coarse woody debris, etc.) are being measured on 5 year rotations.
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| Figure 1. Example of harvesting pattern (top) and hypothesized crown profile (bottom) for 20-10 treatment on block #1 over time. |
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Treatment
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% of Basal Area
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Regeneration cycle (years)
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Successional goal
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Research area assignment
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Removed in a cycle
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Retained in retention trees
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20-10
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20
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10
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50 (rest 50)
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Middle
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1,6,9
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10-30
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10
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30
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100
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Late
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2,5,7
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Control
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N/A
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N/A
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Natural
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Natural
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3,4,8
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Table 1. The above treatments are being applied to nine 10 ha plots within the Penobscot Experimental Forest in Bradley, Maine.
Design Details
An expanding-gap silvicultural system with permanent reserve trees maintains structural diversity and controls species composition, while providing ease of marking and harvesting. The prescriptions, derived from natural disturbance patterns in the Acadian ecoregion, include: (1) a 20% canopy removal on a 10-year cutting cycle (creating 0.2 ha openings) with 10% of the basal area left in permanent reserve trees is designed to maintain a mid-successional status; and (2) a 10% disturbance level on a 10-year cycle (creating 0.1 ha openings) with 30% of the basal area left in permanent reserve trees is intended to accelerate late-successional composition.
These treatments are being compared to control areas that receive no harvesting. The treatment plots are each about 10 ha in size and replicated three times in a randomized complete block design. Data collected before harvest and periodically since initial harvesting include descriptions of overstory, reserve tree characteristics, overstory gap fraction, tree regeneration, understory vegetation, snag and coarse woody debris, soils, arthropods, and songbirds. Post-harvest measurements were made three years after treatment and long-term monitoring is occurring on five-year cycles.