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 40DBH 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 40DBH 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 40DBH 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 110Age

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 110Age

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