Interspecific differences in rates of base
cation immobilization in the stem of some
hardwoods of eastern Canada
Patricia Boucher and Benoît Côté
Macdonald Campus, McGill University
Québec, Canada
Soil - Tree System vs Nutrient availability

Soil factors






Geology
Texture
Thickness
Slope
Drainage
Soil flora and fauna
etc.

Plant/species effects

Uptake



Litter

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
Roots
Leaves
Roots
Leaves
Throughfall/stemflow
The forgotten: nutrient immobilization
TIM = U - R



Where TIM = Tree nutrient immobilization
U = total nutrient uptake
R = total nutrient returns
Sustainability of forest nutrition

Linked to exportations of nutrients

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Soils
Leaf litter
Tree biomass
Natural losses (leaching, denitrification etc)
Rate vs Mass

Nutrient pools at maturity


to measure exportation via exploitation
Rates of nutrient immobilization in tree
biomass before maturity
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Could be a more sensitive variable
Could provide an earlier signal
Could compare species at different ages
Why hardwoods?


Conifers are reputed to be soil acidifiers
Hardwoods can acidify soils even faster
(Johnson and Todd 1990)

Which hardwoods have the highest potential for
soil acidification?


American beech, sugar and red maple?
Poplar, basswood, ash?
Objectives


Assess the rate of base cation (K, Ca and
Mg) immobilization in the stem of selected
hardwoods of eastern Canada
Establish relationships between rates of
immobilization, and tree age and size
Hypotheses



Trees of intermediate age and size will have
maximum rates of nutrient immobilization
Late-successional species (e.g. beech and
maple) would have the highest overall rates
of base cation immobilization
Some species would show a weak/strong
affinity for specific elements
Study site

Morgan Arboretum, McGill, Montreal

Great Lakes - St. Lawrence forest

Rich site
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Brunisol, pH 7
Sugar maple, basswood, white ash (40-100 yrs old)
Poor site


Podzol, pH 4.5
American beech, red maple, red oak (40-100 yrs old)
Allometric equations
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3 trees per species were cut down (20, 30 and 40
cm in diameter)
5-10 cm thick discs were cut from the base of the
stem and subsequent 3-m intervals to a stem
diameter of 9 cm
Discs were separated into heartwood, sapwood,
transitional zone, bark
Developed for sugar and red maple, beech, red
oak, basswood and white ash
Tree sampling
heartwood
transition
bark
sapwood
Forest sampling
• 6 species sampled
•basswood, sugar maple &
white ash
•beech, red oak & red
maple
• 20-25 trees per species
•one increment core per tree
(age and DBH)
•Area per tree = Projection of
the crown to the ground
Rate of nutrient immobilization
(g/m2/yr)
Based on :
• tissue concentration (mg/g)
• wood density (g/cm3)
• stem volume (cm3)
• age (years)
• crown projection (m2)
K concentrations (mg g-1)
Species
heartwood
transition
sapwood
bark
White ash
1.5b
1.5b
1.0c
2.9a
Sugar maple 1.8b
0.65d
0.9c
2.8a
Basswood
4.2a
0.9c
1.4b
1.6b
Beech
0.7b
0.8b
0.6b
1.25a
Red oak
0.8b
1.1a
1.1a
1.0a
Red maple
1.1a
0.6b
0.55b
1.0a
Ca concentrations (mg
-1
g )
Species
heartwood
transition
sapwood
bark
White ash
0.44c
0.45c
0.53b
17a
Sugar maple 4.5b
1.0c
0.9c
20a
Basswood
5.5b
1.1c
1.2c
16a
Beech
0.8b
0.6b
0.7b
22a
Red oak
0.4c
0.8b
0.9b
21a
Red maple
1.3b
0.7c
0.8c
11a
Mg concentrations (mg
-1
g )
Species
heartwood
transition
sapwood
bark
White ash
0.13c
0.12c
0.18b
1.5a
Sugar maple 0.9a
0.19b
0.14c
0.9a
Basswood
1.1a
0.2b
0.2b
1.2a
Beech
0.2b
0.2b
0.2b
0.6a
Red oak
0.03b
0.2a
0.3a
0.4a
Red maple
0.3a
0.2b
0.1b
0.4a
Tissue proportion (v/v)
125
heartwood
Transitional
Sapwood
Bark
percentage (v/v)
100
75
50
25
0
White ash
Sugar maple
Basswood
Beech
Red oak
Red maple
K immobilization (kg tree-1)
3
2.5
Content (kg)
2
K
white ash
sugar maple
basswood
beech
red oak
red maple
1.5
1
0.5
0
20
30
DBH class (cm)
40
Ca immobilization (kg tree-1)
5
Content (kg)
4
3
white ash
sugar maple
basswood
beech
red oak
red maple
2
1
0
20
30
DBH class (cm)
40
Immobilization rate vs Age
Species
K
Ca
Mg
White ash
--
---
---
Sugar maple
+
NS
NS
Basswood
---
---
--
Beech
NS
NS
NS
Red oak
NS
NS
+
Red maple
NS
NS
NS
Immobilization rate vs DBH
Species
K
Ca
Mg
White ash
NS
NS
NS
Sugar maple
+++
++
+++
Basswood
NS
NS
NS
Beech
++
+
++
Red oak
+++
+++
+
Red maple
+++
+++
+++
Mg immobilization (kg tree-1)
60 0
50 0
Content (g)
40 0
white ash
sugar maple
basswood
beech
red oak
red maple
30 0
20 0
10 0
0
20
30
DBH class (cm)
40
Ca immobilization rate vs Age
Ca - basswood
4
4
3.5
3.5
Immobilization rate (g/m2/yr)
Immobilization rate (g/m2/yr)
Ca - sugar maple
3
2.5
2
1.5
1
3
2.5
2
1.5
1
0.5
0.5
0
0
20
30
40
50
60
70
Age
80
90
100
110
20
30
40
50
60
70
Age
80
90
100
110
Ca immobilization vs DBH
Ca - basswood
Ca - sugar maple
4
Immobilization rate (g/m2/yr)
Immobilization rate (g/m2/yr)
4
3.5
3
2.5
2
1.5
1
0.5
3.5
3
2.5
2
1.5
1
0.5
0
0
10
20
30
40
DBH (cm)
50
60
10
20
30
40
DBH (cm)
50
60
Conclusions

Interspecific differences:


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Large beech and sugar maple immobilized more
base cation per inch of DBH (generalists)
White ash is high in K
Red oak is low in Mg
Nutrient, age, DBH relationships


Immobilization rates decrease with age in early
successional species on the rich site
Immobilization rates increases with size in
others
Conclusions (continued)


Species growing together on a particular
site are likely to develop different patterns
of base cation immobilization over time that
may contribute to an efficient utilization of
site nutrients throughout stand development
Generally difficult to rank species in terms
of rates of nutrient immobilization