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Interspecific differences in rates of base cation immobilization in the
stem of some hardwoods of eastern Canada
Patricia Boucher and Benoît CôtéMacdonald 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
Roots Leaves
Litter 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 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 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 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
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
bark sapwood
transition
heartwood
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 g-1)
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 g-1)
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)
K immobilization (kg tree-1)
20 30 40
DBH class (cm)
0
0.5
1
1.5
2
2.5
3
Content (kg)
white ashsugar maplebasswoodbeechred oakred maple
K
Ca immobilization (kg tree-1)
20 30 40
DBH class (cm)
0
1
2
3
4
5
Content (kg)
white ashsugar maplebasswoodbeechred oakred maple
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)
20 30 40
DBH class (cm)
0
100
200
300
400
500
600
Content (g)
white ashsugar maplebasswoodbeechred oakred maple
Ca immobilization rate vs Age
20 30 40 50 60 70 80 90 100 110
Age
0
0.5
1
1.5
2
2.5
3
3.5
4
Immobilization rate (g/m2/yr)
Ca - sugar maple
20 30 40 50 60 70 80 90 100 110
Age
0
0.5
1
1.5
2
2.5
3
3.5
4
Immobilization rate (g/m2/yr)
Ca - basswood
Ca immobilization vs DBH
10 20 30 40 50 60DBH (cm)
0
0.5
1
1.5
2
2.5
3
3.5
4
Immobilization rate (g/m2/yr)
Ca - sugar maple
10 20 30 40 50 60DBH (cm)
0
0.5
1
1.5
2
2.5
3
3.5
4
Immobilization rate (g/m2/yr)
Ca - basswood
Conclusions Interspecific differences:
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