Northwest Advanced Renewables Alliance

How do residual biomass removals affect long-term forest productivity?:

Long-term Soil Productivity (LTSP) studies

Scott M. Holub, Ph.D.Silviculture Research Scientist

Weyerhaeuser CompanySpringfield Oregon

February 18, 2015MOSS Imagine Tomorrow Webinar

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OBJECTIVE OF TODAY'S PRESENTATION

• Briefly describe Weyerhaeuser Company and the processes we use to achieve sustainable site productivity and meet stewardship objectives to:

minimize soil erosion and harmful soil disturbance

maintain or enhance organic matter and soil nutrition

• Present information about two studies looking at the effects of biomass removal on Long Term Soil Productivity.

WEYERHAEUSER IS ONE OF THE WORLD’S

LARGEST PRIVATE FOREST LANDOWNERSAND HARVEST ONLY A SMALL PERCENTAGE EACH YEAR

~2.5 million acres in western Oregon and Washington

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WEYERHAEUSER FORESTRY

Weyerhaeuser Forestry has resource strategies for:

- Forest Products- Water Quality- Wildlife Habitat

-Soil Productivity

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WEYERHAEUSER FORESTRY

•Commitment to sustainable forestry:

Soil is an integral part of the forest – no crop can be managed sustainably without considering the soil that supports it.

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Organic Matter/Soil Nutrient - Management Principles

• Conserve organic matter/nutrients throughout the managed forest cycle

• Balance nutrient inputs/outputs through successive rotations

• Follow Best Management Practices

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SOIL & NUTRIENT MANAGEMENT PRINCIPLES

Loss of topsoil and associated litter layers can reduce soil productivity potential by:

•Reducing organic matter - reduces moisture holding capacity/infiltration

•Relocating nutrients -- leading to localized areas of low soil fertility

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Soil aeration and macro-pore space are critical determinants of soil productivity:

–Soil compaction can be detrimental, neutral, or beneficial depending on the level of pore space and texture of the undisturbed soil and the degree of macro-pore space

–Disruption of pore space continuity can also impact water movement

SOIL & NUTRIENT MANAGEMENT PRINCIPLES

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Soil productivity potential can be enhanced:

•Compacted soil layers -- soil cultivation

•Nutrient deficiencies -- nutrient amendments

SOIL & NUTRIENT MANAGEMENT PRINCIPLES

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NARA Biomass Removal Research

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WHAT IS NARA?

NorthwestAdvancedRenewablesAlliance

www.nararenewables.org

NARA is the name given to the group of organizations involved in a $40 million biofuel grant from USDA AFRI.

Goal:Convert Douglas-fir woody biomass to jet fuel.

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ENVIRONMENTAL SUSTAINABILITYPart of NARA’s Mission:

… meet the high environmental standards of the Pacific Northwest.

15 | 8/13/2014

SOIL PRODUCTIVITY/SLASH REMOVALConcern:Removing slash removes nutrients and

compacts soil.

Question:Does slash harvest for biofuel feedstock affect future site growth capacity?

Implications: Sustainability / Carbon neutrality / Policy

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LONG TERM SOIL PRODUCTIVITY NETWORK

Map Credit: Andy Scott, USFS

Regional Studies in Coastal

Douglas-fir

Matlock, WAFall River, WA

Molalla, ORNARA LTSP

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NARA LTSP TIMELINE

2012 – Site indentified/plotted – 83 acres near Springfield, Oregon. 28 1-acre plots.Soil nutrients (June/July) / Pre-harvest tree, etc. measurements (Sept/Oct).

2013 – Harvest (Feb-May) / Biomass removal and compaction treatments (May-July). Install weather instruments and soil water collection (July-Sept). Fence site (Nov) 2014 – Plant seedlings, initial tree measurements (March/April).First season tree measurements / 15 year measurements at Fall River LTSPContinue monitoring site conditions / Grad student projects.

2015 – Second-year tree measurements (Oct). Report drafted by mid-2016.

2016-beyond Monitor site conditions, measure trees at year 5, 10, 15, etc.

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CompactionOM Removal

C0 – No compaction C1 - Moderate compaction

OM0 – Bole only OM0 C0Boles removed /No compaction

OM0 C1Boles removed /Moderate compaction

OM1 - Boles and crowns removed

OM1 C0Boles & crowns removed /No compaction

OM1 C1Boles & crowns removed /Moderate compaction

OM2 - Boles, crowns, forest floor removed

OM2 C1Boles, crowns & forest floor removed /Moderate compaction

* F&G = + mid-rotation fertilization

NARA LTSP Treatments-L

evels

of

Sla

sh

Rem

oval-

A C

B D/F*

E/G*

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NARA POST-TREATMENT AERIAL PHOTO

Photo taken October 2013 – Post treatment – looking west across the north part of the study

Total Tree Removal

No Forest Floor

Bole only Removal

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NARA LTSP - TREATMENT LAYOUT

Bole only / No compTotal Tree/ No compTotal Tree/ Compacted

Bole only/ CompactedForest Floor/ CompTotal Tree/ Compacted*Forest Floor/ Comp*

* With mid-rotation fertilization

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NARA POST-TREATMENT CONDITIONS

Good separation. Pre-harvest range also shown

A

B

C

D/F

E/GPre-harvest range

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INSTRUMENTATION - NARA LTSP

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• Standard Weather Stations (2)– Harvested area – Forest

Every plot (28) + 4 in Forest:• Soil moisture and temperature

– 10, 20, 30, 100 cm

• 15 cm Air temperature and Relative Humidity

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COLLABORATION - NARA LTSP

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• Jim Rivers / Matt Betts– OSU– Wildlife: Pollinators

• Jeff Hatten / Adrian Gallo – OSU – Soil Nutrients, Carbon/respiration

• Rob Harrison / Marcella Menegale – UW – Nutrient leaching

• Mike Barber / Mohammad Hasan– U. Utah (WSU) – Water issues / Microbial assessment

• Larger LTSP Network

Looking for more…

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PRELIMINARY RESULTS: SOIL TEMPERATURE

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Fall River LTSP

Weyerhaeuser's 15 year oldSoil Productivitystudy in western Washington

Summer 2009

Block 1

Block 2Block 3

Block 4

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FALL RIVER LTSP - OBJECTIVES

Determine the impact of:

Biomass removalCompaction and tillage Weed control(Fertilization)on stand productivity and soil and nutrient processes in a fertile Pacific Northwest Douglas-fir plantation

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BIOMASS REMOVAL TREATMENTS

Bole only (BO)Conventional harvest

Total-tree plus all coarse woody debris (TT+)

Total tree

Bole only to 5-cm top

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BIOMASS REMOVAL - TREE VOLUME AGE 10

Reference Treatment

No significant difference

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COMPACTION +/- TILLAGE TREATMENT

47% of area trafficked during shovel-yardingAerial view

“Non-compacted”Cable-Yarding

“Compacted” Shovel-Yarding

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COMPACTION/TILLAGE - TREE VOLUME

Reference Treatment

No significant difference

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FALL RIVER LTSP - CONCLUSIONSAt this productive, nutrient rich site very modest, if any, declines in tree growth were seen in high biomass removal vs standard practices.

Compaction/Disturbance at the level we did had no negative effects on tree growth.

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GENERAL LTSP - CONCLUSIONSAcross the network of other LTSP sites generally we don’t see large losses in productivity from the experimental removal of residual biomass.

Where fall-down has occurred it was on sites with low nutrient levels prior to harvest so those are potentially the most at risk.

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End