Kim Littke Rob Harrison David Briggs University of Washington
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Understanding Site-Specific Factors Affecting the Nutrient
Demands and Response to Fertilizer by Douglas-fir
Center for Advanced Forestry Systems 2010 Meeting
Kim LittkeRob HarrisonDavid Briggs
University of Washington
Rationale Nitrogen fertilization is a common practice in
Douglas-fir forests of the Pacific Northwest The Regional Forest Nutrition Research Project
studied the effect of N fertilization over western Washington and Oregon
However, growth response to N fertilization was widely variable
No site and soil factors have been confirmed as response predictors for Douglas-fir
Center for Advanced Forestry Systems 2010 Meeting
Objectives Test soil variables including bulk
density, nutrient pools, temperature, and moisture
Record non-soil variables such as site index, LAI, elevation, slope, precipitation, air temperature, and relative humidity
Determine which factors can predict N fertilizer response
Focus on variables that are easily obtained
Center for Advanced Forestry Systems 2010 Meeting
Experimental Plan 15-30 year-old Douglas-fir stands in British Columbia,
Oregon, and Washington Range of landform, elevation, and slope Measure DBH, height, and crown height of 48
dominant Douglas-fir Pair trees according to the best matches for DBH and
crown height Fertilize one tree per pair with 224 kg N/ha Select up to 20 pairs per installation
Center for Advanced Forestry Systems 2010 Meeting
Paired Tree Design
Center for Advanced Forestry Systems 2010 Meeting
Paired Tree Installations
Center for Advanced Forestry Systems 2010 Meeting
Red Markers – Glacial parent material
Green Markers – Sedimentary parent material
Blue Markers – Igneous parent material
Progress 60 Douglas-fir installations
2 ponderosa pine 25 glacial 19 sedimentary 18 igneous
59 installations have soil sampled and weather stations installed
Complete weather station data for one growing season for 31 installations
Six installations with two-year growth dataCenter for Advanced Forestry Systems
2010 Meeting
10 12 14 16 18 20 22 24 26 2830
35
40
45
50
55
60
65
70
75
80
f(x) = 2.3010285625884 x + 17.095698104463R² = 0.612644140939803
Age at Breast Height
Heig
ht (ft
)
Adna 2
Adna 1
Arrowhead Lake
Oppelt Rd
Cherry Grove 1 Cherry Grove 2
Site Quality
Center for Advanced Forestry Systems 2010 Meeting
Soil Nitrogen to 1 Meter
Center for Advanced Forestry Systems 2010 Meeting
0
5000
10000
15000
20000
25000
30000
Arrowhead Lake
Oppelt RdAdna 1Adna 2
Cherry Grove 1
Cherry Grove 2
Soil
Nitr
ogen
Con
tent
(kg
N/h
a)
IgneousGlacialNorth to South
Sedimentary
Basal Area Growth Percent
Center for Advanced Forestry Systems 2010 Meeting
Cherry Grove 1 Cherry Grove 2 Adna 1 Adna 2 Arrowhead Lake
Oppelt Rd0
5
10
15
20
25
30
35
a
b
Control 224 kg N/haInstallation
Basa
l Are
a Gr
owth
(%)
Height Growth Percent
Cherry Grove 1 Cherry Grove 2 Adna 1 Adna 2 Arrowhead Lake
Oppelt Rd0
2
4
6
8
10
12
14
16
ab
Control 224 kg N/ha
Installation
Heig
ht G
row
th (%
)
Center for Advanced Forestry Systems 2010 Meeting
Volume Growth Percent
Center for Advanced Forestry Systems 2010 Meeting
Cherry Grove 1 Cherry Grove 2 Adna 1 Adna 2 Arrowhead Lake
Oppelt Rd0
5
10
15
20
25
30
35
40
45
50a
b
Control 224 kg N/haInstallation
Volu
me
Grow
th (%
)
Foliage Area after fertilization
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Control Fertilized
Foliar N Concentration
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Control Fertilized1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
Adna 1Adna 2Arrowhead LakeCherry Grove 1Cherry Grove 2Oppelt Rd
Folia
r Nitr
ogen
Con
cent
ratio
n (%
)
Basal Area Growth Response
Center for Advanced Forestry Systems 2010 Meeting
8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
R² = 0.486277867911935
Soil Nitrogen Content (kg N/ha)
Basa
l Are
a Gr
owth
Res
pons
e (%
)
Height Growth Response
Center for Advanced Forestry Systems 2010 Meeting
1.25 1.30 1.35 1.40 1.45 1.50 1.55
-0.5
0.0
0.5
1.0
1.5
2.0
R² = 0.736267779847595
Foliar N concentration – Control (%)
Heig
ht G
row
th R
espo
nse
(%)
Timeline Two-year growth data for 28 installations fall
2010 Foliage, forest floor, and soil sampling 26 installations will be measured fall 2011
Four-year growth data to be measured 2011, 2012, and 2013
Background soil samples to be finished spring 2010
Weather stations maintained twice yearly
Center for Advanced Forestry Systems 2010 Meeting
Deliverables and Budget Establishment of Paired Tree Installations
throughout the Pacific Northwest Derive a model to predict fertilizer response
based on site and soil factors $20,000 for the next year Other support from:
Stand Management Cooperative Agenda 2020
Center for Advanced Forestry Systems 2010 Meeting
total funding $195,078
Center for Advanced Forestry Systems 2010 Meeting
Center for Advanced Forestry Systems 2010 Meeting
Center for Advanced Forestry Systems 2010 Meeting
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