Soil Properties Influencing Loblolly Pine Growth at Stand Closure on Wet Pine Flats in South Carolin

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Soil Properties Influencing Loblolly Pine Growth
at Stand Closureon Wet Pine Flats in South
Carolina

• M. H. EISENBIES, J. A. BURGER, W. M. AUST
  Virginia Tech
• and
• S. C. PATTERSON MeadWestvaco Corp.

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Dissertation Objectives

• 20-year study
• Do logging disturbances affect soil quality,
  hydrologic function, and forest productivity?
• Can forestry practices mitigate disturbance
  effects if they exist?
• Dissertation
• Investigate the effect of scale on
  interpretations of objectives 1 and 2.

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Objective

• Examine the effects of harvesting disturbance on
  long-term productivity.
• Estimate the change in site productivity at
  different scales using field measures of soil
  disturbance combined with readily available
  spatial information and GIS tools.
• Identify potentially sensitive harvesting zones
  at the landscape scale using GIS.

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Study Location
Study Site
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General Study Design - Operational Scale
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Study Design Treatment and Measurement Layout

• Multiple Scales
• 3 20-ha Blocks
• 15 3.3-ha Treatments
• 1170 0.008-ha Subplots
• 203 measured annually

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Comparing Productivity between Rotations

• Retrospective vs. Long-Term Studies
• Methods for tracking Long-Term Productivity
  (Vance 2000)
• Long-term Production (NPP, Volume, Site Index)
• Soil Properties
• Conservation of Mass
• Nutrient Budgets
• Environmental Quality
• Confounding Factors for Production Comparisons
• Climate
• Planting Density
• Bedding Density
• Genetics
• Drainage Classes
• Inherent Temporal Variability of Soil Productivity

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Growth Rates Ages 5-7Current and Prior Stand
Operational Scale
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Hypothesis

• Forest Productivity (Plant Potential, Climate,
  Soil/Site Quality, and Catastrophe) (Morris and
  Miller, 1994)
• Soil/Site Quality (Silvicultural Treatments,
  Harvesting Disturbance, and Inherent Site
  Factors)
• Bedding and Drainage
• Soil Physical Disturbance
• Amount and Distribution of Harvesting Residue
• Landscape-level Site Factors
• Local Site Factors
• Assumption Absent of disturbance, the rank of
  Soil/Site Quality for a specific location will
  remain relatively constant within its
  neighborhood at any point in time.

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Advantages of using Rank

• Rank is largely independent of the confounding
  factors associated with comparing rotations
• Rank does not have outliers
• Change in rank emphasizes changes that occur near
  the median of the Site Index Distribution
• Change in rank is normally distributed

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Relative Productivity Rank
20-ha Block
After Treatments 2000
Before Harvest 1993
0.008-ha Subplot
Rank 0.008 ha Subplot Site Index Within a 20-ha
Block
Relative Productivity Rank (RP)

• .
• .
• .

Change in Rank ? Operational Norm
Productivity Diminished
Change in Rank ? Operational Norm
Productivity Maintained
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Soil/Site Quality (Silvicultural Treatments,
Harvesting Disturbance, and Inherent Site
Factors)
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Final ModelChange in Rank (SI) is the Response
Sequential Sums of Squares

• 198 Observations (0.008-ha subplots)
• Mallows Cp was the primary model selection
  diagnostic
• 6 candidate models were evaluated
• Adjusted R2 62

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Model Accuracy ? Rank at the Stand (0.008 ha)
and Operational Scale (3.3 ha)
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Change in Rank (SI) at the Operational Scale 15
3-ha Treatment Units (P 0.0013 R2 0.93)
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Change in Rank (Biomass) at the Operational Scale
15 3-ha Treatment Units (P 0.0007 R2 0.95)
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Change in Relative Productivity as a function of
Bedding, Prior Site Index, and Relative Elevation
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Map of Harvesting Risk Based on Relative Elevation
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Conclusions

• When bedded, harvesting disturbance has a minimal
  influence on changes in site productivity
  compared to the operational norm.
• Soil/Site Quality (Silvicultural Treatments,
  Harvesting Disturbance, and Inherent Site
  Factors)
• bedding
• distance to landing
• prior site index, soil order, relative elevation
• Sites with higher initial site quality are more
  at risk, particularly those sites with low
  relative elevations.

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Project Overview

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Methods and Scale (Issem, 2002)
Stand Scale
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Root-Soil Interface ScaleGreenhouse Study
Increasing Wetness Decreasing Aeration
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Original Matrix of Harvesting DisturbanceDisturba
nce Scale

• Soil Physical Disturbance
• Undisturbed
• Compressed
• Shallow Rutted
• Deep Rutted
• Churned
• Harvest Residue
• Piles
• Heavy Slash
• Light Slash
• Litter
• Bare Soil

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Methods and Scale (Kelting, 2000)

• Disturbance Scale
• LLWR
• Aeration Depth
• Net Nitrification
• R2 0.80

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Least Limiting Water Range in Soil (Kelting, 2000)
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Least Limiting Water Range in Soil (Kelting, 2000)
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Soil Disturbance and Site Preparation Effects on
Pin LLWR (Kelting, 2000)
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Study Design Treatment and Measurement Layout

• Multiple Scales
• 3 20-ha Blocks
• 15 3.3-ha Treatments
• 1170 0.008-ha Subplots
• 203 measured annually

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Modifying the HypothesisTaking the Conceptual
Matrix of Harvesting Disturbancefrom the
Disturbance Scale to the Stand Scale

• 3 x 3 x 2 Matrix Design
• Site Preparation
• Bedded
• Flat Planted
• Soil Physical Disturbance
• Undisturbed
• Compressed
• Rutted and Churned
• Harvest Residue
• Slash
• Litter
• Bare Soil

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Soil/Site Quality (Silvicultural Treatments,
Harvesting Disturbance, and Inherent Site
Factors)

• Site Specific Factors
• Least Limiting Water Range
• F (Texture, Carbon, Clay Content)
• Oxidation Depth
• Net Nitrogen Mineralization
• Bedding Quality
• Rooting Volume
• Organic Residues

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Summary of Scales

• Root-Soil Interface (Issem, 2002)
• Disturbance Scale (Kelting, 2000)
• Stand Scale (20 m)
• Regression
• Factorial
• Operational Scale (3.3 ha)
• RCBD
• Regression
• Landscape Scale
• Temporal Scale
• Rank approach allows comparisons between
  rotations
• Stem analysis